text stringlengths 454 608k | url stringlengths 17 896 | dump stringclasses 91
values | source stringclasses 1
value | word_count int64 101 114k | flesch_reading_ease float64 50 104 |
|---|---|---|---|---|---|
Kernel 2.6 is finally here, and it touts several enhancements over the 2.4 series. The press has highlighted changes relevant to systems architects and managers, but there’s plenty in 2.6 for application developers, too.
This month’s column provides an overview of some updates and new features in 2.6, including filesystem support, threading library changes, and the new kernel-level profiler. This article assumes you already have access to a machine running 2.6. For features that must be explicitly enabled, the kernel config option (such as CONFIG_PROFILING) is listed.
Asynchronous I/O
Asynchronous I/O (AIO) separates I/O operations from the calling function. Similar to running a shell command in the background, an application constructed with AIO can issue a series of long-running requests and immediately continue its other processing. Later on, the application can go back and check the results of those operations. AIO-enabled programs appear more responsive because the I/O operations occur independently of the application’s main event loop.
While it’s possible to realize asynchronous I/O with threads, the AIO calls do the work for you: you needn’t design your own framework to accept I/O requests and publish the results.
Once you’ve installed a recent build of the libaio library, you’re ready to AIO-enable your apps.
1. First, create a context using io_setup().
2. Associate a series of I/O calls with the context using io _submit().
3. Later, call io_getevents() to retrieve the status and results of context operations, or call io_cancel() to cancel them.
4. Finally, cleanup the context using io_destroy().
Don’t forget to install the developer version of the AIO package, such as Fedora’s libaio-devel, to get the header files.
Filesystems and Synchronous Directories
The advanced capabilities of the Reiser Filesystem (ReiserFS), the Journaling Filesystem (JFS), and Silicon Graphics’ XFS filesystem are hardly new, but they were previously available only as kernel patches. By upgrading to 2.6, conservative shops can now take advantage of these filesystems without patching their kernels.
Applications that rely heavily on the filesystem sometimes need something stronger than the standard ext3. For example, an application that places thousands of files in a single directory would benefit from ReiserFS’s scalability. Another application that does a lot of file I/O would be more resilient to system crashes with JFS’s journaling capabilities.
One feature new to all filesystems is synchronous directories. With a slight performance penalty, changes made in a synchronous directory are committed to disk before control returns to the caller. To make a directory synchronous, run chattr +S /some/directory. To verify that the bit is set, use lsattr -d /some/directory.
To enable ReiserFS, JFS, and XFS in the kernel, look for the CONFIG_REISERFS_FS, CONFIG_JFS_FS, and CONFIG_ XFS_FS options, respectively.
Access Control Lists
One deficiency of the traditional Unix permissions model is that it limits access control to a single user, a single group, and other (everyone else that isn’t the owner and not in the owning group). Sometimes, however, you want to grant access to several users that are unrelated (at the system level, at least). In 2.6, fine-grain permission can be achieved with access control lists (ACLs).
For example, the following command grants read-write access to the file semi-private.txt to bob, yet read-only access to peggy:
$ setfacl -m u:bob:rw,u:peggy:r semi-private.txt
Here -m modifies the ACL, and u specifies that user (as opposed to group) attributes are being changed. Similar to chmod‘s symbolic mode, r stands for read access and w for write access.
An overview of the ACL system is provided in the acl man page. C and C++ programs can alter ACLs using the acl_ set_file() system call.
Extended Attributes
Extended attributes (EAs) are key/value pairs of metadata, or information about the file that’s not part of its contents. While Linux EAs are limited to plain text, you can apply them in any number of novel ways. For example, you could implement a last-modified-by attribute for shared files.
EAs can be managed from command-line tools as well as a native API. To set attributes, use the command setfattr or the system call setxattr(); to fetch them, use getfattr or getxattr().
As an example, the following command and system call both set the pub_date attribute of the file article.txt to “June 2004″:
$ setfattr -n pub_date -v “June 2004″ article.txt
);
One caveat to ACLs and EAs: you must use tools that recognize ACLs and extended attributes (such as an updated version of tar or cp) or all “extended” information will be lost as you move files around.
Access Control Lists (ACLs) are available as module options for ext3, JFS, and XFS filesystems. Extended attributes are supported for ext2 and ext3.
The relevant kernel configuration options are CONFIG_EXT3_FS_POSIX_ACL, CONFIG_JFS_POSIX_ ACL, and CONFIG_XFS_POSIX_ACL for ACLs; and CONFIG_EXT2_FS_XATTR and CONFIG_EXT3_FS_XATTR.
The epoll() System Calls
Graphical user interface (GUI) programs and some daemons use poll() to watch for changes on a file. The new epoll system works like poll(), but is much more scalable: whereas poll() scrolls through its entire list of file descriptors to check for events, epoll registers callbacks on its file descriptors that fire when an update occurs.
To use the new polling system:
1. Create a special epoll file descriptor with epoll_create().
2. Use epoll_ctl() to add file descriptors to the watch list.
3. Call epoll_wait() to check for events on watched file descriptors.
4. Close the epoll file descriptor with the standard system call close().
OProfile and the System-Wide Profiler
Profiling is the first step in performance tuning: it shows where a program burns CPU cycles. Traditional profiling requires that you rebuild your program, so that the compiler can insert hooks into the object files. Those new binaries then generate data from which profilers (such as gprof) extract trace statistics.
The method works, but has flaws: even when rebuilding is an option, detailed traces require debug symbols (enabled with the compiler’s -g flag) that can often conflict with other compiler optimizations. So, all in all, you never profile the real, production program.
The new 2.6 kernel exposes a system-wide profiling interface that doesn’t require intrusive recompiles. It also supports profiling the kernel itself, and the system as a whole. In turn, the OProfile toolkit () pulls in trace data via this kernel interface.
OProfile’s opcontrol configures and controls the profiler; opreport fetches profile data and can pull system-wide statistics or analyze a single program; and opgprof generates an input file readable by gprof. The OProfile web site provides additional documentation.
The system-wide profiling feature is enabled using the CONFIG_PROFILING option.
CPU Affinity
By default, a process in a multi-processor machine typically bounces between several CPUs. In some cases, explicitly binding a process to certain CPUs, or assigning CPU affinity, may yield several benefits:
* INCREASED CPU CACHE HITS. In caching, a hit occurs when data is pulled from a cache instead of being copied anew from the original, slower source. CPU affinity increases a process’s cache hit ratio.
* IMPROVED PERFORMANCE ON NUMA SYSTEMS. In NUMA systems, one CPU can be “closer” to a piece of memory than another. Relatively slow bus speeds may make it more efficient to use the local, burdened processor instead of a remote, idle processor.
* CONTAINING AN UNRULY PROCESS. A resource-intensive process can be limited to select processors, leaving the rest free for other tasks.
Linux 2.6 achieves CPU affinity with the system calls sched_ getaffinity() and sched_setaffinity():
#include <sched.h>
int sched_setaffinity(pid_t pid, unsigned
int len, unsigned long *mask);
int sched_getaffinity(pid_t pid, unsigned
int len, unsigned long *mask);
Specifying 0 as the pid argument gets or sets the affinity for the current process. len is the size of a word on the system. The mask argument is a series of bits that represent the system’s processors, where a set bit indicates the process may use that CPU. Therefore, unsetting all but one bit limits the process to that single CPU.
Great New Threads
The new kernel also brings several thread-related changes. For one, the kernel itself is preemptive: some kernel-space operations can be interrupted to yield to user processes. This is especially relevant for GUI applications, which require maximum responsiveness.
Second, the kernel is based on a 1:1 model, in which a kernel thread is available for each user thread. The internal O(1) scheduler lets the kernel efficiently handle a greater number of threads than previous versions, so this doesn’t burden the system. Better still, thread creation and tear down are both faster and less costly.
Kernel 2.6 includes support for the Native Posix Thread Library (NPTL). Among other benefits, the enhanced POSIX compliance improves signal handling. For example, it’s possible to send a signal (such as SIGSTOP) to an entire multi-threaded process.
However, migration of existing code to NPTL isn’t automatic: you’ll have to rebuild your application to take advantage of its features. Several new thread functions are available, and some underlying library changes may wreak havoc on old code. For example, all threads in a process report the same process ID (PID).
In spite of the backward binary compatibility, some older, non-NPTL code can still get confused running on a newer system. You can disable NTPL on a per-process basis by setting the environment variable LD_KERNEL_ASSUME to a previous kernel revision (say, 2.4.1 or 2.2.5).
Seqlocks and Futexes
Still on the topic of threads, 2.6 brings seqlocks and futexes.
Seqlocks fill a very specific niche: they protect shared access to non-pointer variables in sections of frequently-called code. To use a seqlock, wrap the data to be protected in calls to write_ seqlock() and write_sequnlock(). For example, using the age-old example of updating a shared counter, you’d write:
#include <linux/seqlock.h>
seqlock_t lock;
seqlock_init( &lock );
int counter = 0;
…
write_seqlock( &lock );
++counter;
write_sequnlock( &lock );
seqlock_t lock;
seqlock_init( &lock );
int counter = 0;
…
write_seqlock( &lock );
++counter;
write_sequnlock( &lock );
A futex (or fast user-space mutex) is a synchronization primitive that heads to kernel space only to resolve contention. To prevent contention in the first place, it supports setting priorities on waiting threads. Other synchronization methods, such as semaphores and mutexes, are built on futexes.
The documentation explains that futexes aren’t for everyday development, but the API is available for anyone who wishes to explore (perhaps to create a new method of synchronization).
Core File Naming
Core dumps enhance the debugging process, from early development to production deployment. Whereas previous kernels created files of the format core or core.pid, 2.6 supports dynamic naming of core files based on printf()-style modifiers.
For example, %p represents the PID, and %h is the hostname. You can provide as much (or as little) detail as you want. Use sysctl to set the kernel.core_pattern variable. For instance, this command names core files for the hostname, process ID, and process owner (user):
# sysctl -w kernel.core_pattern=”core.%h-%p-%u”
/proc and /sys
If you’ve written tools based on the contents of the /proc directory, your code may be due for an update. As of 2.6, there are new entries in the /proc/pid/status and /proc/pid/stat files. The format of /proc/meminfo has also changed.
In addition to /proc and /dev/pts, kernel 2.6 introduces a third pseudo-mount called /sys. Where /proc contains information about running processes and kernel stats, /sys represents the machine’s hardware tree. (Some of /proc‘s hardware-related trees also exist under /sys now.)
For example, to determine whether the disk device sda is online, you could read the file /sys/block/sda/device/online.
To mount the /sys filesystem, run mount -t sysfs none /sys or add the proper line to /etc/fstab to make this permanent.
/sys is of interest to people writing hardware-related tools, similar to the procps suite that interfaces the /proc directory. It’s also closely tied to the kobject interface, which is relevant to writers of hardware kernel modules.
Loadable Modules
There are several changes to the kernel module system. First of all, there is a cosmetic change: kernel objects now have the extension .ko instead of .o.
Building third-party modules is more uniform, and folded into the kernel build process in a framework-like fashion. Simply drop your code into place and the build system takes care of adding the appropriate flags and such. With a proper makefile, an external module can be built with a simple command, such as:
$ make -C /path/to/kernel/source SUBDIRS=/path/to/module/source modules
Inside the code itself, the MODULE_LICENSE macro serves a twofold purpose: writers of third-party modules can identify themselves and their module’s license, and the running kernel can identify modules released under a GPL-compatible license.
Related to MODULE_LICENSE is EXPORT_SYMBOL_GPL(), which limits access of the current module’s exported symbols to other GPL-friendly modules. The kernel prevents non-GPL modules from accessing this data.
kexec: Linux Within Linux
When booting Linux on an x86 machine, the BIOS probes for hardware and passes control to the kernel. A patch for kernel 2.6 provides the kexec family of system calls, which permit the kernel loaded by the BIOS to load another kernel.
The ability to start Linux from Linux opens up new realms of possibilities, from faster reboots, to crash recovery, to booting the main kernel from devices not supported by most x86 BIOSs (after they’ve been probed by the first kernel). If you’ve worked with commercial Unix hardware (say, Sun’s or HP’s), you’ll recognize this last feature is sorely lacking on x86 machines.
Use of kexec requires the userspace kexec-tools suite () and a kernel patch ().
Something for Everyone
The new Linux kernel has something for everybody: end-users, system administrators, and even application developers. If you’ve been holding out for the official kernel release to start updating your apps, your wait is over. | http://www.linux-mag.com/id/1684/ | CC-MAIN-2016-44 | refinedweb | 2,380 | 55.44 |
Seven great PHP IDEs compared
Oct 10, 2006 ... ...
Test and deploy PHP applications automatically on IBM Bluemix
Aug 21, 2017 ... You will walk through the process of configuring an IBM Bluemix Continuous
Delivery toolchain to monitor and deploy a PHP application from GitHub to an
IBM ... the PHP dependency manager; The Cloud Foundry command-line tool;
The Git command-line tool (or any other Git client); A text editor or IDE. 1 ...
Build Web services with PHP in Eclipse
Jul 1, 2008 ... PDT overview. The PDT project gives you the ability to do PHP development
using the Eclipse IDE. It includes many features of the Java editing environment,
including syntax highlighting, code templating, perspectives, and file and project
wizards.
Leveraging PHP V5.3 namespaces for readable and maintainable ...
Mar 1, 2011 ... ...
Debugging PHP using Eclipse and PDT
Jun 17, 2008 ... Everyone else can find the Eclipse integrated development environment (IDE) at
the Eclipse downloads. Apache or Microsoft Internet Information Services (IIS) for
serving Web applications: You need a Web server installed to run the examples
that demonstrate how to debug PHP Web pages on the server.
Build an Eclipse development environment for Perl, Python, and PHP
Build an Eclipse development environment for Perl, Python, and PHP. Use the
Dynamic Languages Toolkit (DLTK) to create your own IDE. Matthew Scarpino
and Nathan Good Published on February 03, 2009/Updated: October 27, 2011 ...
Introducing Quercus, a Java-based PHP framework
Sep 22, 2009 ... ...
PHP V5.3 の名前空間を利用して、理解しやすく保守の容易なコードを ...
2011年3月1日 ... Zend Studio にも同じような機能が用意されています。名前空間を使い始めることを
ためらっている人は、IDE をアップグレードし、お気に入りの IDE のヘルプを参照して
名前空間を試してみてください。場合によっては IDE をアップグレードする必要もない
かもしれません。多くの IDE は PHP V5.3 の機能を 1 年以上も前から提供し ...
Build a notepad application with PHP, MongoDB, and IBM Bluemix
Dec 15, 2015 ... This article shows you to use IBM Bluemix to build and deploy a web-based
notepad application with PHP, MongoDB, and Bootstrap. It uses MongoDB for
fast and scalable document storage, the Slim PHP micro-framework for the
application's business logic, and Bootstrap for a responsive, mobile-friendly ...
Squash bugs in PHP applications with Zend Debugger
Squash bugs in PHP applications with Zend Debugger. Clever IDE finds and
helps you fix bugs interactively. From the developerWorks archives. Martin
Streicher. Date archived: January 4, 2017 | First published: November 13, 2007.
A special application called a debugger probes running code, allowing you to
suspend ...
Develop, deploy, and manage your apps in the cloud
The IBM Cloud platform has everything you need to get started.
Build on IBM Cloud for free | https://www.ibm.com/developerworks/topics/ide%20for%20php/ | CC-MAIN-2018-05 | refinedweb | 413 | 66.03 |
AgentServerObjects
From IronPython Cookbook
Windows includes this bizarre feature called 'AgentServerObjects'. These are little animated characters that fly around the screen, making announcements and doing quite odd and quirky things.
They don't get used very much, in fact it is hard to see what you could use them for. But they're certainly fun.
Merlin looks like this:
and:
In order to run this example I generated the interop dll in 'c:\'. Run tlbimp like this (more on Interop introduction):
C:\>set PATH=%PATH%;C:\Program Files\Microsoft Visual Studio 8\SDK\v2.0\Bin C:\>tlbimp c:\WINDOWS\msagent\agentsvr.exe
The code to make this dude fly around your screen is:
import sys)
Cool...
More details here, and some example C# here. | http://www.ironpython.info/index.php/AgentServerObjects | crawl-002 | refinedweb | 125 | 67.65 |
C++ provides us with a number of ways we can shoot ourselves in the foot. If
you work as a developer on any sizeable software project, there is quite likely
a set of rules about limitations as to the C++ language features you’re allowed
to use: no memory allocation in constructors, no operator overloading,
exceptions used only for error handling, etc. Repentance for violating these
rules often resembles that for breaking the master build—i.e. some
obligation to perform some menial yet necessary task for the group and/or the
possession of some object of indistinction (“The Hat” or “The Hose”).
There are, however, reasons for flexibility where at least some of these
rules are concerned, and I’ll offer as an example some practical considerations
in favor of allowing the use of operator overloading for
operator() (that’s read as “function-call
operator”). If you happen to be one of the lucky ones who work on projects with
only one or two other programmers, or even just by yourself, stick around.
‘Cause function objects are cool, and I’m about to tell you why.
Those of us who write software for the Macintosh know that the world is really
divided into three: Windows, Macintosh and Unix. How do we know this? Because
we’re constantly having to manipulate the line endings of various text files.
Curiously enough, the standard Mac OS X install doesn’t have a neat little
command-line tool for converting line endings (or at least “apropos” with
various forms of the phrase “convert line endings” yields “nothing
appropriate”). There isn’t even one among the little more than two dozen
command line tools in Apple’s Developer Tools.
So, if you often find yourself having to flip the line endings of various
text files, you’ll either open them all up in, say, XCode or BBEdit, and
manipulate the line endings by hand, or you’ll write a little command line tool
that will do what you need. The benefit of the latter is that it can handle
large numbers of files all at once.
Should you write one such tool, you’re quite likely to have three different
functions in your code that look something like this:
/*----------------------------------------------------------------------------
%%Function: ClnConvertToWin
%%Contact: richs
----------------------------------------------------------------------------*/
int ClnConvertToWin(InputFile &in, OutputFile &out)
{
char chPrev = chNul;
int cln = 0;
for (;;)
{
int ch = in.ChGet()
if (in.FEof())
break;;
}
return cln;
}
This code, which converts an arbitrary input file to Windows’ line endings,
looks simple enough. It reads a character from the input file one character at
a time, and performs some specific action based on which character is just
read. It keeps track of the number of lines that it’s converted, and returns
that count when it’s all done.
The two other versions of this function likely have the exact same loop
control and differ only by the structure of the
switch statement that does the actual conversion of line
endings.
This is bad, because you now have three separate loops in your code that are
almost identical. Suppose, for example, that you move this code to a system
where the “read a character, then test for end-of-file” construct isn’t the
most efficient or robust way to read characters from a file. You now have three
separate loops of code to change, and three separate opportunities to create
bugs in the code.
In the old days, we might have resolved this problem by using function
pointers, but they’re clumsy. Also, function pointers provide no opportunity
for the compiler to optimize out the function-call semantics. You’re going to
be stuck with full procedure prologue and epilogue with every iteration through
that loop. For performance reasons, as well as maintenance reasons, we don’t
want to use function pointers in this particular application.
With C++, however, we can encapsulate the
switch statement into a function
object, and put the control loop in a template function that takes as a
parameter a reference to an object that overloads
operator().
The template that encapsulates the loop might look like:
/*----------------------------------------------------------------------------
%%Function: ClnConvertLines
%%Contact: richs
----------------------------------------------------------------------------*/
template <class CharConverter>
int ClnConvertLines(InputFile &in,
CharConverter &cnv)
{
int cln = 0;
for (;;)
{
int ch = in.ChGet();
if (in.FEof())
break;
cnv(ch, cln);
}
return cln;
}
And the function object that converts arbitrary line endings to Windows
might look like:
/*----------------------------------------------------------------------------
%%Class: ToWin
%%Contact: richs
----------------------------------------------------------------------------*/
class ToWin
{
public:
ToWin(InputFile
&anIn, OutputFile &anOut) :
in(anIn),
out(anOut),
chPrev(chNul) {};
~ToWin() {};
void operator()(int ch,
int &cln)
{;
};
private:
int chPrev;
OutputFile &out;
InputFile ∈
};
With that, our original conversion function becomes:
Inline int ClnConvertToWin(InputFile &in, OutputFile &out)
{
ToWin cnv(in,
out);
return ClnConvertLines(in,
cnv);
}
I should point out that there is no a priori reason for
ClnConvertLines to be a
template. We could have defined a
base class,
CharConverter,
that virtualized
operator(),
and made
ToWin a subclass
of
CharConverter. In this particular case, however, the
virtualized base class approach isn’t any better than the old-style, function
pointer approach. In fact, on some
systems, it’s worse, because you have the double-dereference through an object’s
v-table instead of the single dereference of a function pointer.
The template-based solution, while it yields more object code in that
ClnConvertLines will get instantiated
for every different flavor of
cnv
object we give it, is much faster for our application. Because the template-based solution
gets expanded in line, there is an opportunity for the compiler to optimize out
the function-call semantics where the overloaded
operator() is invoked—one
of those rare instances where we get to have our cake and eat it too.
Now, if that weren’t cool enough, the fact that we’ve abstracted out the
actual conversion of line endings into a separate piece of source code leads to
a flexibility one wouldn’t want to entertain in the purely functional
approach. For example, suppose we know that a particular input file has Macintosh line endings. Scanning the beginning of an input file
to figure out the existing line endings isn’t all that hard, and is well worth
the time if it greatly simplifies our inner loop. The implementation of the
line conversion from Macintosh to Windows line endings is almost trivial:
/*----------------------------------------------------------------------------
%%Class: MacToWin
%%Contact: richs
----------------------------------------------------------------------------*/
class MacToWin
{
public:
MacToWin(OutputFile &anOut) :
out(anOut) {};
~MacToWin() {};
void operator()(int ch,
int &cln)
{
out.PutChar(ch);
if (ch
== chCR)
{
out.PutChar(chLF);
cln++;
}
};
private:
OutputFile
&out;
};
You wouldn’t entertain something like this in the purely functional
approach, because the proliferation of code with the same loop semantics is
something you want to avoid. If having just three duplicates of that outer loop
is bad, having one for every possible known combination of input and output
line endings is that much more of a maintenance headache. With function objects, we can proliferate
to our heart’s content without increasing the level of maintenance required
should we decide to change the semantics of the loop control.
By now, there’s at least one astute reader who’s thinking, “Gosh, Schaut,
flipping line endings isn’t all that different from iterating through one of
the Standard Template Library’s collection classes. Using function objects should be obvious. What’s all the fuss about?”
Such an astute reader would be absolutely correct: they way I’ve used
function objects here is almost exactly the way function objects are used in
the STL. In fact, we can take that
line of thought and extend it to the concept of an input iterator.
Think about how one might use a command-line tool to convert line
endings. Some times, you’ll want
to just invoke the tool on a single file.
Other times, you’ll want to invoke the tool on a whole bunch of files in
a single directory. On still other
occasions, you’ll want to use some complex
find
command to generate a list of files in an entire directory tree, and pipe the
output of that command through the line converter’s standard input file.
So, you’ll have two distinct ways of getting a list of files to convert: as
an array of C-style strings provided on the command line or as a list of file
names coming in via your standard input file. The structure of the loop to convert files and report the
progress of that conversion to the user ought not change simply because we’re
getting a list of files in two distinctly separate ways. This problem screams for a solution
where input iterators are implemented as function objects.
I’ll leave the actual implementation of this as an exercise for the reader,
but there is one thought to consider.
The input iterator is in an outer loop, not an inner loop, and the
function that figures out which particular conversion loop to invoke is likely
to be complex enough that we wouldn’t want multiple copies of it in our object
code. In this case, I would avoid
a template-based approach in favor of defining a base class for our input
iterators where the
operator()
is virtualized.
Hopefully, this will lead some of you to think more about using function
objects in your daily work—in particular, I’d want you to think that
function objects are useful outside something as complex as the Standard
Template Library. If function
objects can improve our implementation of something as mundanely simple as
flipping line endings in text files, they just have to be cool enough to use in
a wide variety of contexts.
Rick Schaut
Currently playing in iTunes: Sierra Leone by Derek Trucks Band
Update: Fixed the template definition for ClnConvertLines (convert to HTML entities).
A cool way to convert between Unix and Windows EOLs is to open one file as binary and another one as text. For example:
using namespace std;
ifstream in ("c:\tmp\win.txt");
in >> noskipws;
ofstream out ("c:\tmp\ux.txt", ios_base::out | ios_base::binary);
copy (istream_iterator<char> (in), istream_iterator<char> (), ostream_iterator<char> (out));
Completely ignoring the main thrust of the blog (productive forays to the seemier side of C++), here’s how I handle line endings:
# linefeed control
alias mac2unix "perl -pi -e ‘s/r/n/g’ !*"
alias mac2pc "perl -pi -e ‘s/r/rn/g’ !*"
alias unix2mac "perl -pi -e ‘s/n/r/g’ !*"
alias unix2pc "perl -pi -e ‘s/n/rn/g’ !*"
alias pc2unix "perl -pi -e ‘s/rn/n/g’ !*"
alias pc2mac "perl -pi -e ‘s/rn/r/g’ !*"
I always wonder why people fight with C and C++ when there are more suitable languages for APPLICATION development, C and C++ are not app programming languages.
Really, why fight with C++ when you can get the same job done easier faster and get paid the same with a higher level language, I know which option I would take, my free time and health is worth more than Karma 😀
If you feel you must "fight" with C++, you’re not the target market. C++ can be as high-level as you want it to be as long as you know it well.
ok, colour me surprised. From the looks of it’s just not there.
dos2unix has been around on just about every *ix system I’ve used since the late 80’s – I’m surprised if there’s not a version on OS X.
By the way, Rick, functors good. It’s not like I didn’t pay attention.
But what you really want for line ending conversion is a state machine which doesn’t care what its input is and produces whatever output you want. This is because as a user you just want to toss a pile of files at the tool without regard to where they came from as long as you are reasomably confident they are all text. This can be implemented pretty easily and it has the added advantage of repairing files whose line endings are not consistent (more common than you would think in large collections). I really should have shipped that silly little toy I wrote oh-so-many-moons ago to do this, but about then text editors rightly started getting agnostic about line endings and I stopped caring.
Pete,
If you take a look at the implementation of the ToWin functor, that’s exactly what it does: converts arbitrary, or eve mixed, line endings to Windows. Equivalent ToMac and ToUnix functors are equally trivial (in fact even simpler).
I wrote all of this as part of my own command-line utility that handles multiple files in a number of ways (including dealing with files that might be locked for writing).
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Read Part 3 of this article series to create Asp.Net Core application deployment package.
Overview
As we continue our learning, we will use the deployment package created using the techniques discussed in previous part and host the application. Though Asp.Net Core application has new a webserver called Kestrel, it is required that the Asp.Net Core application should be deployed behind a full-fledged webservers like IIS, Nginx or Apache as reverse proxy. In next section, we will understand this hosting model in detail.
Asp.Net Core Hosting Environment
Before delving into the details of hosting the app, it will be better if we understand the basics of Asp.Net Core hosting environment. As we know, Asp.Net Core applications will come with its own in-process webserver called Kestrel. Traditionally, all we did is use the IIS webserver to host our Asp.Net application which has taken care of every aspect of our application hosting. Since, Asp.Net Core platform is developed as cross platform framework, the Asp.Net Core app should be able to run under other common webservers like Nginx, Apache, etc. apart from IIS. Like IIS, different webservers has different start-up mechanisms. This means that the Asp.Net Core app should adopt different start-up mechanisms based on the webserver it is targeted. Instead of adopting different start-up for different webservers, Asp.Net Core has included a light weight, cross platform webserver called Kestrel to have consistent start-up behaviour across platforms. But, Kestrel webserver does not have all the capabilities of a full-fledged webservers like IIS, Nginx, Apache, etc. to take care of all aspect of hosting by itself. For example, Kestrel did not have the capability to share same port number for different web sites while webservers like IIS do with the help of host header value. It is an in-memory webserver which does not have a management console, not as secured as IIS, etc.
Read the quick start article Learn Kestrel Webserver in 10 Minutes to understand more about Kestrel webserver.
So, the recommended deployment option for Asp.Net Core application is to use the webservers like IIS, Nginx, and Apache as a reverse proxy and host the application using Kestrel. This means the webservers (IIS, Nginx, and Apache) will get the request from users and it will just forward the request to Kestrel using HTTP for processing and the get the response back from Kestrel to send it back to users.
To understand, why it is called reverse proxy we should first understand what a proxy does. There is a proxy in every network that intercepts request from users before forwarding to outside (server or website). The proxy has an authority to deny connection to a destination based on pre-defined rules set by the network admin. In general, a proxy intercepts and moderates the out bound request from a network user like below,
Similarly, a reverse proxy intercepts request from a user in outside network and forwards them to a configured destination inside a network. Thus, a webserver reverse proxy (IIS, Nginx, and Apache) intercepts inbound request and forwards it to an Asp.Net Core App (Kestrel) similar to below.
The communication between reverse proxy server and Kestrel can happen in plain http since the communication is internal. This means we can restrict the use https on the IIS site and kestrel can just receive the request using plain http. Thus, by hosting Asp.Net Core app behind these full-fledged webservers as reverse proxy gives us everything we need for hosting the app and on other hand, we can also use the capabilities of the full-fledged webservers for our applications.
With these information, let’s move ahead and see how we can host Asp.Net Core app behind IIS. The .Net Core SDK when installed it provides a native IIS module called Asp.Net Core Module to forward request to Asp.Net Core app. This can be seen in the IIS Management console under Modules.
The Asp.Net Core applications runs in a separate process as opposed to traditional Asp.Net application where the application itself runs under IIS worker process. The new process model looks like,
Configuring Application to Use Core Module
To make the IIS website to use Asp.Net Core IIS module, we need to include Web.Config file in our application root with following configuration setting,
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<system.webServer>
<handlers>
<add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified" />
</handlers>
<aspNetCore processPath="dotnet" arguments=".\ASPNETCoreVS2017Demo.dll" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" />
</system.webServer>
</configuration>
Note – Publishing you project with Visual Studio will automatically include this web.config file in the output directory.
As you can see above, the above configuration will make the IIS to handle all the requests to any path (*) by Asp.Net Core module. The Asp.Net Core module will forward it to Kestrel and get back the response after processing. This clearly indicates that IIS worker process (w3wp.exe) does not process our request instead it just runs the Asp.Net Core module to forward the request to Asp.Net Core App as seen in the process model diagram above.
It is now the responsibility of Asp.Net Core module to load the application when the first request arrives and make sure the application is running to process the incoming requests. When there is a failure in application, it is the responsibility of the core module to re-run the application to service the incoming requests. Read here to know more about configuration settings of Asp.Net Core module.
The application level configuration for setting up Kestrel and IIS integration is done in the Main() method under Program.cs class. Let’s examine this method to understand how the above process wiring is done.
public class Program
{
public static void Main(string[] args)
{
var host = new WebHostBuilder()
.UseKestrel()
.UseContentRoot(Directory.GetCurrentDirectory())
.UseIISIntegration()
.UseStartup<Startup>()
.UseApplicationInsights()
.Build();
host.Run();
}
}
Unlike, traditional Asp.Net project the Asp.Net Core project is a console application with Main method and it is the entry point to our application. When the Asp.Net Core Module calls the application first time, this method executes and it sets up the hosting environment for request processing. The WebHostBuilder object uses Fluent Builder pattern (Method Chaining) to configure the application to take up request processing.
The UseKestrel() method setup the Kestrel webserver and starts listening to a default port 5000 for incoming request. You can change the default port by calling WebHostBuilder.UseUrls("") method. The UseIISIntegration() method integrates the application with IIS Asp.Net Core module. The Startup class for setting the Asp.Net Core pipeline is configured by calling UseStartup<Startup>() method as seen in the above code. Finally, calling Run() actually starts the application with all the configuration we provided by chaining the WebHostBuilder methods.
Steps to Host Asp.Net Core App behind IIS as Reverse Proxy
Open IIS Manager. Type inetmgr in RUN and press Enter.
Right Click Sites Node and Select “Add Website..” Specify a site name and configure the physical path where you have published the release files. For avoiding conflict with the default site, I have specified the port 8000. Click Ok.
This will create a new website and add a new Application Pool with same name as of the site. Since, IIS did not host our site we can set the Application Pool to not use .NET. This will give some performance benefit. To do this, got to Application Pools Node, right click the app pool and select “Basic Settings..”. Change .Net CLR Version to “No Managed Code” like below.
That’s it, we are done with hosting a simple Asp.Net Core app by using IIS as reverse proxy. Let’s understand hosting Asp.Net Core App using Nginx and Apache in another article.
Open browser and visit. You will see the application coming up.
Happy Coding!! | http://www.codedigest.com/posts/20/beginning-aspnet-core---part-4---deploying-and-hosting-aspnet-core-application | CC-MAIN-2017-22 | refinedweb | 1,328 | 58.48 |
Blog::Spam::API - A description of Blog-Spam API.
This document discusses the API which is presented by the Blog::Spam::Server to remote clients via XML::RPC.
The server itself has two APIs:
This is the API which is presented to remote callers.
The API that the server itself uses, and which plugins must conform to, in order to be both used and useful. The internal plugin API is documented and demonstrated in the the sample plugin.
The Blog::Spam::Server exposes several methods to clients via XML::RPC.
The following methods are documented as being available:
This is the method which is used to test a submitted comment from a blog or server. Given a structure containing information about a single comment submission it will return a result of either "spam" or "ok".
This returns the names of the internal plugins we use - it is used such that a remote machine may selectively disable some of them.
Return the number of spam vs. non-spam comments which have been submitted by the current site.
If a previous "testComment" invocation returned the wrong result then this method allows it to be reset.
Each of these methods will be discussed in order of importance, and additional documentation is available online.
The testComment method has the following XML-RPC signature:
string testComment( struct );
This means the method takes a "struct" as an argument, and returns a string. In Perl terms the struct is a hash.
When calling this method the hash of options may contain the following keys:
The user-agent of the submitting browser, if any.
The body of the comment the remote user submitted.
The email address submitted along with the comment.
If this key is present your comment will always be returned as SPAM; useful for testing if nothing else. This handling is implemented by the plugin Blog::Spam::Plugin::fail.
The IP address the comment was submitted from.
The name of the comment submitter, if any.
The subject the comment submitter chose, if any.
A HTTP link to your site which received the comment submission. In most cases using $ENV{'SERVER_NAME'} is the correct thing to do.
Customization options for the testing process, discussed in the section TESTING OPTIONS.
The only mandatory structure members are "comment" and "ip", the rest are optional but recommended.
The return value from this method will either be "OK", or "SPAM".
Optionally a reason may be returned in the case a comment is judged as SPAM, for example:
SPAM:I don't like comments submitted before 9AM.
The classifyComment method has the following XML-RPC signature:
string classifyComment( struct );
This means the method takes a "struct" as an argument, and returns a string. In Perl terms the struct is a hash.
The keys to this method are identical to those in the testComment method - the only difference is that an additional key, "train", is recognised and it is mandatory:
If the comment was permitted to pass, but should have been rejected as SPAM set the train parameter to "spam", if it was rejected and should not have been set the train parameter to "ok".
The getPlugins method has the following XML-RPC signature:
array getPlugins( );
This means the method takes no arguments, and returns an array.
This method does nothing more than return the names of each of the plugins which the server has loaded.
These plugins are modules beneath the Blog::Spam::Plugin:: namespace, and their names are the module names minus the prefix.
The getStats method has the following XML-RPC signature:
struct getStats( string );
This method returns a struct and takes a string as its only argument.
This method returns a hash containing two keys "OK" and "SPAM". These keys will have statistics for the given domain - or global statistics if the method is passed a zero-length string.
Note: The string here should match that given as the "site" key to the method testComment - as that is how sites are identified.
When a comment is submitted for testing, via the testComment XML::RPC method it may have an "options" key in the structure submitted.
The options string allows the various tests to be tweaked or changed from their default behaviours.
This option string should consist of comma-separated tokens.
The permissible values are:
whitelist=1.2.3.0/24 - Whitelist the given IP / CIDR range. blacklist=1.2.3.3/28 - Blacklist the given IP / CIDR range. exclude=plugin - Don't run the plugin with name "plugin". (You may find a list of plugins via the getPlugins() method.) mandatory=subject,email - Specify the given field should always be present. max-links=20 - The maximum number of URLs, as used by L<Blog::Spam::Plugin::loadsalinks> min-size=1024 - Minimum body size, as used by L<Blog::Spam::Plugin::size>. min-words=4 - Minimum word count, as used by L<Blog::Spam::Plugin::wordcount>. max-size=2k - Maximum body size, as used by L<Blog::Spam::Plugin::size>. fail - Always return "SPAM".
These options may be repeated, for example the following is a valid value for the "options" setting:
mandatory=subject,mandatory=name,whitelist=1.2.3.4,exclude=surbl
That example will:
1. Make the "subject" field mandatory.
2. Makes the "name" field mandatory.
3. Whitelists any comment(s) submitted from the IP 1.2.3.4
4. Causes the server to not run the surbl plugin.
This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The LICENSE file contains the full text of the license. | http://search.cpan.org/dist/Blog-Spam/lib/Blog/Spam/API.pm | crawl-003 | refinedweb | 929 | 65.52 |
Here we go again. As you can see, I have gotten much further. There are some elements however that I am unsure how to apply (i.e. bool tooMany). I haven't the slightest how to apply that. That is one snag that I have. Another, and the main one, is this:
The following code does work. It calls a file called "studentData.txt". Said file contains the ID#s and Scores on their own lines :
(id) 101
(score) 100
102
95
103
90
...
...
121
0
Now, if I comment that out and just have it read from the arrays that I have hardcoded it works great. I can't quite figure out how to compute the .txt items into the individual arrays to make it use those as opposed to the hardcoded arrays. One of my main issues with reading from a .txt file, is that the only way I know how is using the getline feature. Is there anything better?
Currently I have the code calling the .txt file.
#include <iostream> #include <fstream> #include <iomanip> #include <string> using namespace std; void printTable(int score[], int id[], int count); void printGrade(int oneScore, float average); void readStudentData(ifstream &rss, int scores[], int id[], int &count, bool &tooMany) { const int MAX_SIZE = 21; rss.open("studentData.txt"); string line; id[MAX_SIZE]; int score[MAX_SIZE]; count = 0; int oneScore = 0; float average = 0; string grade; for(count = 0; count < MAX_SIZE; count++) { getline(rss,line); cout << line; getline(rss,line); cout << " " << line; cout << " " << grade << endl; } // printTable(score, id, count); } float computeAverage(int scores[], int count[]) { const int MAX_SIZE = 21; return 0; } void printTable(int score[], int id[], int count) { void printGrade(int oneScore, float average); const int MAX_SIZE = 21; int oneScore = 0; float average = 0; string grade; id[MAX_SIZE]; score[MAX_SIZE]; cout << left << setw(9) << "ID#s" << setw(9) << "Scores" << setw(9) << "Grades" << endl << endl; //for(count = 0; count < MAX_SIZE; count++) //{ printGrade(oneScore,average); //} } void printGrade(int oneScore, float average) { const int MAX_SIZE = 21; int id[MAX_SIZE] = {101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121}; int scores[MAX_SIZE] = {100,95,90,85,80,75,70,65,60,55,50,45,40,35,30,25,20,15,10,5,0}; oneScore = 0; average = 0; string grade; int sum = 0; for(int i = 0; i < MAX_SIZE; i++) sum += scores[i]; average = sum / MAX_SIZE; for(int i = 0; i < MAX_SIZE; i++) { if(scores[i] > average + 10) { grade = "outstanding"; } else if(scores[i] < average - 10) { grade = "unsatisfactory"; } else { grade = "satisfactory"; } // cout << left << setw(9) << id[i] << setw(9) << scores[i] << setw(9) << grade << endl; } } int main() { ifstream rss; string line; const int MAX_SIZE = 21; int scores[MAX_SIZE]; int id[MAX_SIZE]; int count; bool tooMany; readStudentData(rss, scores, id, count, tooMany); return 0; } | https://www.daniweb.com/programming/software-development/threads/201597/snagged-yet-again | CC-MAIN-2017-09 | refinedweb | 468 | 65.76 |
I was tasked with implementing a .NET Web Service to provide access to our application data by outside entities. The Web Service must support clients written in .NET languages, Visual Basic 6.0, and non-Microsoft languages. All access to our database must be through stored procedures, so we did not need to support running direct SQL queries. The design was to use a single method that accepts an XML string that describes the stored procedure to run, its parameters, and how to return the data if any data is returned (DataSet XML or Recordset XML). The implementation used the .NET data access objects to return a DataSet and ADODB objects to return a Recordset. The returned data was then serialized to an XML string and returned to the caller. At first, this worked like a charm, however, as soon as the load testing started, it was obvious, I had a problem. At the web server, a single user returning a large set of data utilized 70% of the CPU; two simultaneous users pegged it at 100%, five or more users - some would get timeouts! This was very bad!
DataSet
Recordset
I knew going in that there would be some performance penalty for using ADODB in the .NET code, but I never dreamed it would be so pronounced. It seems that the penalty for using COM interop from .NET can be quite severe. Back to the drawing board.
Now for the problem, I knew from the beginning that if I had to provide the XML node list that a DataSet persists in a form, along with the XML schema, any .NET or non-Microsoft client should easily be able to use to utilize the data, then the plan for returning persisted Recordset formatted XML to VB 6.0 clients was in serious jeopardy. So far as I knew, there was no native way to convert a DataSet to an ADODB Recordset in VB.NET. Knowing that someone, somewhere was bound to have had this problem before me, I began to search the internet to see if anyone had come up with a solution that I could use. I found a couple of articles that had VB 6.0 code that use the .NET node list and schema to construct an ADODB Recordset, but they were client side solutions, I needed something that would work on the server. I found a Microsoft Support article: How To Convert an ADO.NET DataSet to ADO Recordset in Visual Basic .NET, that appeared to be exactly what I had been searching for.
I followed the instructions in the article, set up the code, and it worked! The only problem I had now was that the example code from Microsoft was writing the XML to a file and reading an XSL file. Since I need this to be a server solution, I needed to eliminate the file IO. No big deal, I altered the code to generate the XSL on the fly in a string (it was quite small), and used a MemoryStream to contain the XML instead of a file. I tried this out and it worked. Now I had to test it against some real world data. I set up some test code to pull data from our test database, and sent it through the conversion function to see what I get on the other side.
MemoryStream
The first problem I saw was that the only fields getting a data type were integers and strings, for all other fields the data type was blank. This was causing an error when attempting to load the Recordset from the ADODB Stream. I tracked down where the code was determining the data type, and sure enough, integers and strings were all they were trapping for. I added several data types and a Case Else that set anything I was not specifically trapping, to type string. Thinking this should work, I tried another run and still got an error loading the XML into the Recordset. I commented out all of the fields returned in the stored procedure except one, ran again, and it worked. I repeated this process, un-commenting another field each time, trying to figure out what type of field I was having a problem with. It turned out to be date-time fields. After a bit of research, I found that in the DataSet, the date-time format included time zone information. For the Recordset to accept a date-time with this additional time zone information, the data type in the XML must be set to dateTime.iso8601tz. I made this change, attempted another run, and it worksed.
Case Else
dateTime.iso8601tz
Now I wrapped the code in a class and integrated it into the Web Service and began unit testing. I ran through a couple of calls, then hit another problem - binary fields. This one took a while to research, but I found that binary fields in a DataSet are persisted as base64 encoded strings; the ADODB Recordset expects binary fields to be persisted as binary hex encoded strings. Since the Microsoft code for transforming the data portion of the DataSet is the part that uses the XSL transformation, there was no opportunity to re-encode the data in a binary field. First, I tried setting the data type in the XML to bin.base64. This allowed the Recordset to load the data without an error, but, the binary data ended up stored in the Recordset as a string field containing the base64 encoded string. In order to have the Recordset convert the field to binary upon loading, as it should, it must be encoded in binary hex, and the data type in the XML set to bin.hex. To solve this, I rewrote the transformation code to loop through the DataSet, and added the data to the XML using the XmlTextWriter just like the rest of the code does to add the header and schema information. This gave me the chance to detect binary fields and binary hex encode them.
bin.base64
bin.hex
XmlTextWriter
Now I needed to find or write a function to perform the binary hex encoding. I couldn't find any ready-made code on the internet, but, I did find information on binary hex encoding. BinaryHex encoding simply takes each octet (byte) of the binary stream, divides it into two 4 bit nibbles, and places the hexadecimal character representing that nibbles value in the output string. For example, if you have 32 bits of binary data:
BinaryHex
10010010111100011010110011010100
divide into octets (bytes):
10010010 11110001 10101100 11010100
divide the octets into 4 bit nibbles:
1001 0010 1111 0001 1010 1100 1101 0100
decimal values of nibbles:
9 2 15 1 10 12 13 4
hexadecimal values:
9 2 F 1 A C D 4
encoded string representing the original 32 bit binary value:
"92F1ACD4
Armed with the above information, it was simple to write a small function to binary hex encode a byte array and return the resultant string. I added this to the class, modified the data transformation code to detect binary fields, and applied this new function to the data. Now I have a conversion class that I can use. The only thing that you may need to update is the function that determines the data type to put in the XML. If you need a data type that I'm not trapping, returning it as a string is not sufficient, just add a Case statement for your data type to the function.
Case
Now, on to the code!
This article assumes that you are familiar with the following topics:
It should be noted here that I started with the code in the above mentioned Microsoft Support article. The code presented, however, is a substantial update of that code.
Note: You must call the FillSchema method of the DataAdapter to obtain the schema information with your DataSet. If you do not, all fields will be created as a string data type.
FillSchema
DataAdapter
The GetADORS function provides the entry point and logic flow for the class. It also creates the MemoryStream and XmlTextReader used by the rest of the functions to build the output XML string.
GetADORS
XmlTextReader
Public Function GetADORS(ByVal DS As DataSet, _
ByVal dbName As String) As String
Try
'Create a MemoryStream to contain the XML
Dim mStream As New MemoryStream
'Create an XmlWriter object, to write
'the formatted XML to the MemoryStream
Dim xWriter As New XmlTextWriter(mStream, Nothing)
'Additional formatting for XML
xWriter.Indentation = 8
xWriter.Formatting = Formatting.Indented
'call this Sub to write the ADONamespaces
WriteADONamespaces(xWriter)
'call this Sub to write the ADO Recordset Schema
WriteSchemaElement(DS, dbName, xWriter)
'Call this sub to transform
'the data portion of the Dataset
TransformData(DS, xWriter)
'Flush all input to XmlWriter
xWriter.Flush()
'Prepare the return value
mStream.Position = 0
Dim Buffer As Array
Buffer = Array.CreateInstance(GetType(Byte), mStream.Length)
mStream.Read(Buffer, 0, mStream.Length)
Dim TextConverter As New UTF8Encoding
Return TextConverter.GetString(Buffer)
Catch ex As Exception
'Returns error message to the calling function.
Err.Raise(100, ex.Source, ex.ToString)
End Try
End Function
First, I've added two lines that indicate to the XmlTextWriter that I want the XML to be indented. The entire purpose of this is to make the output XML human readable. These lines can be omitted if you like. Having the output XML easily readable made debugging the class much easier. Next, WriteADONamespaces is called to add the Recordset schema to the output XML. WriteSchemaElement is then called to add the schema elements. TransformData is called to properly format the data and add it to the output XML. Finally, the contents of the MemoryStream are prepared for return as a string.
WriteADONamespaces
WriteSchemaElement
TransformData
Private Sub WriteADONamespaces(ByRef xWriter As XmlTextWriter)
'Uncomment the following line to change
'the encoding if special characters are required
'writer.WriteProcessingInstruction("xml",
' "version='1.0' encoding='ISO-8859-1'")
'Add XML start element
xWriter.WriteStartElement("", "xml", "")
'Append the ADO Recordset namespaces
xWriter.WriteAttributeString("xmlns", "s", Nothing, _
"uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882")
xWriter.WriteAttributeString("xmlns", "dt", Nothing, _
"uuid:C2F41010-65B3-11d1-A29F-00AA00C14882")
xWriter.WriteAttributeString("xmlns", "rs", Nothing, _
"urn:schemas-microsoft-com:rowset")
xWriter.WriteAttributeString("xmlns", "z", _
Nothing, "#RowsetSchema")
xWriter.Flush()
End Sub
The code in WriteADONamespaces is essentially unchanged from the code in the original Microsoft article. I have removed the comment describing the format of this section of the XML.
Private Sub WriteSchemaElement(ByVal DS As DataSet, _
ByVal dbName As String, ByRef xWriter As _
XmlTextWriter)
'write element Schema
xWriter.WriteStartElement("s", "Schema", _
"uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882")
xWriter.WriteAttributeString("id", "RowsetSchema")
'write element ElementType
xWriter.WriteStartElement("s", "ElementType", _
"uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882")
'write the attributes for ElementType
xWriter.WriteAttributeString("name", "", "row")
xWriter.WriteAttributeString("content", "", "eltOnly")
xWriter.WriteAttributeString("rs", "updatable", _
"urn:schemas-microsoft-com:rowset", "true")
WriteSchema(DS, dbName, xWriter)
'write the end element for ElementType
xWriter.WriteFullEndElement()
'write the end element for Schema
xWriter.WriteFullEndElement()
xWriter.Flush()
End Sub
The code in WriteSchemaElement, also, is essentially unchanged from the code in the original Microsoft article. I have removed the comment describing the format of this section of the XML.
Private Sub WriteSchema(ByVal DS As DataSet, ByVal dbName _
As String, ByRef xWriter As XmlTextWriter)
Dim i As Int32 = 1
Dim DC As DataColumn
For Each DC In DS.Tables(0).Columns
DC.ColumnMapping = MappingType.Attribute
xWriter.WriteStartElement("s", "AttributeType", _
"uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882")
'write all the attributes
xWriter.WriteAttributeString("name", "", DC.ToString)
xWriter.WriteAttributeString("rs", "number", _
"urn:schemas-microsoft-com:rowset", i.ToString)
xWriter.WriteAttributeString("rs", "baseCatalog", _
"urn:schemas-microsoft-com:rowset", dbName)
xWriter.WriteAttributeString("rs", "baseTable", _
"urn:schemas-microsoft-com:rowset", _
DC.Table.TableName.ToString)
xWriter.WriteAttributeString("rs", "keycolumn", _
"urn:schemas-microsoft-com:rowset", _
DC.Unique.ToString)
xWriter.WriteAttributeString("rs", "autoincrement", _
"urn:schemas-microsoft-com:rowset", _
DC.AutoIncrement.ToString)
'write child element
xWriter.WriteStartElement("s", "datatype", _
"uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882")
'write attributes
xWriter.WriteAttributeString("dt", "type", _
"uuid:C2F41010-65B3-11d1-A29F-00AA00C14882", _
GetDatatype(DC.DataType.ToString))
xWriter.WriteAttributeString("dt", "maxlength", _
"uuid:C2F41010-65B3-11d1-A29F-00AA00C14882", _
DC.MaxLength.ToString)
xWriter.WriteAttributeString("rs", "maybenull", _
"urn:schemas-microsoft-com:rowset", _
DC.AllowDBNull.ToString)
'write end element for datatype
xWriter.WriteEndElement()
'end element for AttributeType
xWriter.WriteEndElement()
xWriter.Flush()
i = i + 1
DC = Nothing
End Sub
The code in WriteSchema, also, is essentially unchanged from the code in the original Microsoft article. I have removed the comment describing the format of this section of the XML.
WriteSchema
Private Function GetDatatype(ByVal DType As String) As String
Select Case (DType)
Case "System.Int32", "System.Int16", "System.Integer"
Return "int"
Case "System.DateTime"
Return "dateTime.iso8601tz"
Case "System.String"
Return "string"
Case "System.Byte[]"
Return "bin.hex"
Case "System.Boolean"
Return "boolean"
Case "System.Guid"
Return "guid"
Case Else
Return "string"
End Select
End Function
The GetDatatype function has been expanded to handle more data types than the original function. The original function only recognized System.Int32 and System.DateTime. The Case Else has also been added to return string type for all data types not in the Case statement.
GetDatatype
System.Int32
System.DateTime
Private Sub TransformData(ByVal DS As DataSet, _
ByRef xWriter As XmlTextWriter)
'Loop through DataSet and add data to XML
xWriter.WriteStartElement("", "rs:data", "")
Dim i As Long
Dim j As Integer
'For each row...
For i = 0 To DS.Tables(0).Rows.Count - 1
'Write the start element for the row
xWriter.WriteStartElement("", "z:row", "")
'For each field in the row...
For j = 0 To DS.Tables(0).Columns.Count - 1
'Write the attribute that describes
'this field and it's value
If DS.Tables(0).Columns(j).DataType.ToString_
= "System.Byte[]" Then
'Binary data must be properly encoded (bin.hex)
If Not IsDBNull(DS.Tables(0).Rows(i).Item(
DS.Tables(0).Columns(j).ColumnName)) Then
xWriter.WriteAttributeString(DS.Tables(0).
Columns(j).ColumnName, _
DataToBinHex(DS.Tables(0).Rows(i).Item(
DS.Tables(0).Columns(j).ColumnName)))
End If
Else
If Not IsDBNull(DS.Tables(0).Rows(i).Item(
DS.Tables(0).Columns(j).ColumnName)) Then
xWriter.WriteAttributeString(
DS.Tables(0).Columns(j).ColumnName, _
CType( _
DS.Tables(0).Rows(i).Item(DS.Tables(0).
Columns(j).ColumnName), String))
End If
End If
'End the row element
xWriter.WriteEndElement()
'Write the end element for rs:data
xWriter.WriteEndElement()
'Write the end element for xml
xWriter.WriteEndElement()
xWriter.Flush()
End Sub
TransformData adds the "rs:data" section of the XML. The function loops through the DataSet adding "z:row" elements for each data row. This function also adds the end tag for the root (XML) element.
Private Function DataToBinHex(ByVal thisData As Byte()) As String
Dim sb As New StringBuilder
Dim i As Integer = 0
For i = 0 To thisData.Length - 1
'First nibble of byte (4 most significant bits)
sb.Append(Hex((thisData(i) And &HF0) / 2 ^ 4))
'Second nibble of byte (4 least significant bits)
sb.Append(Hex(thisData(i) And &HF))
Return sb.ToString
End Function
The DataToBinHex function performs the encoding of binary data.
DataToBinHex
As long as developers are faced with integrating .NET and VB 6.0, there will be a need to have the ability to pass data from one to the other. In the case where VB 6.0 is the client, the code presented here should help to alleviate the problem. While the code in the Microsoft article was a good starting point, it has a few shortcomings that prevent it from operating correctly in many real world situations. I believe that I have addressed the major concerns and shortfalls, and am presenting code that can be dropped into a project and used "as is" in most situations.
This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.
A list of licenses authors might use can be found here
<z:row
'Prepare the return value
mStream.Position = 0
'Get the recordset and return it
Return MemoryStreamToRS(mStream)
''Line of code above replaces this code
'Dim Buffer As Array
'Buffer = Array.CreateInstance(GetType(Byte), mStream.Length)
'mStream.Read(Buffer, 0, mStream.Length)
'Dim TextConverter As New UTF8Encoding
'Return TextConverter.GetString(Buffer)
Private Shared Function MemoryStreamToRS(ByVal stream As MemoryStream) As ADODB.Recordset
stream.Position = 0
'Create a byte array to be used in converting the stream to a string
Dim Buffer As Array = Array.CreateInstance(GetType(Byte), stream.Length)
'Read the stream into the Buffer
stream.Read(CType(Buffer, Byte()), 0, CInt(stream.Length))
'Create a TextConverter
Dim TextConverter As New UTF8Encoding
'Create an ADODB stream object to hold the xml string
Dim objStream As ADODB.Stream
objStream = New ADODB.Stream
'Write the xml string to the stream
objStream.Open()
objStream.WriteText(TextConverter.GetString(CType(Buffer, Byte())))
objStream.Position = 0
'Open the recordset from the stream
Dim rs As New ADODB.Recordset
rs.Open(objStream)
Return rs
End Function
Public Shared Function GetADORS(ByVal dataTable As DataTable) As ADODB.Recordset
General News Suggestion Question Bug Answer Joke Rant Admin
Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages. | http://www.codeproject.com/script/Articles/View.aspx?aid=13352 | CC-MAIN-2015-35 | refinedweb | 2,903 | 57.47 |
E.g
01110 00110 11001 01010 (2,3) : circumference = 10 (3, 5) or (4,4) : circumference = 4 (4, 2): circumference = 8
Could you clarify the coordinate system used and what exactly is meant by circumference and island?
Suppose that coordinates start at top-left and 1-based. Suppose an island is defined as a group of 1s horizontally or vertically (but not diagonally) adjacent. If this is the case, I can understand the (3, 5) and (4, 4) cases, but others? (4, 1) seems more like 8, and (2, 3) seems more like 10.
@SergeyTachenov You are correct in understanding the coordinate system and the values. I have edited the post with the correct values! (posted in a hurry and hence the mistakes in values)
All right, so here is how I'd approach it. Looking at these islands, the first thing that comes to mind is BFS. Maybe DFS is an option too, but BFS is easier to visualize, and therefore would probably lead to more readable code, at least for those familiar with BFS. On the other hand, DFS may be easier to implement recursively, only we risk stack overflow for really large matrices because recursion may go too deep. So I'd stick with BFS.
Using BFS, we can easily find the island, but what about circumference? First thing that comes to mind here is that we could probably count the number of adjacent zeroes, assuming that everything outside the matrix is filled with zeroes too. But we better be careful here lest we run into edge cases, so let's look at the possibilities.
...0000... ...1111... ...1111...
In this case it's pretty clear that the number of adjacent zeroes will do the trick.
...0000... ...0111... ...0111...
The corner case (literally). But it looks like it's still fine: ignoring diagonally adjacent zero, we get exactly what we need.
...0001... ...0001... ...1111...
Another corner case. Now, here things go wrong. The circumference of this part is 5, and we have only four adjacent zeroes. Which means we have to count the corner zero twice. Or we can count unique adjacent pairs 1-0, then it will be counted twice automatically because one zero is adjacent to two 1s.
...0000... ...0111... ...0000...
Here, either approach works.
...1111... ...1000... ...1111...
And here, we again have to count unique pairs. Looks like it is the correct approach after all.
So, we do BFS, and when we stumble into a zero or the matrix border, we add the pair of coordinates to a set. Then we return the set size.
struct BorderPiece { const int i1, j1, i2, j2; BorderPiece(int i1, int j1, int i2, int j2) : i1(i1), j1(j1), i2(i2), j2(j2) {} bool operator==(const BorderPiece &that) const { return i1 == that.i1 && j1 == that.j1 && i2 == that.i2 && j2 == that.j2; } }; namespace std { template<> struct hash<BorderPiece> { size_t operator()(const BorderPiece &p) const { return (((p.i1 * 17) + p.j1) * 17 + p.i2) * 17 + p.j2; } }; } int circumference(const vector<vector<bool>> &matrix, size_t i, size_t j) { --i; --j; // convert to 0-based const int m = matrix.size(), n = matrix[0].size(); auto get = [&matrix, &m, &n](ptrdiff_t i, ptrdiff_t j) { return i >= 0 && i < m && j >= 0 && j < n ? matrix[i][j] : false; }; using Coords = pair<size_t, size_t>; unordered_set<BorderPiece> border; vector<vector<bool>> visited(m, vector<bool>(n)); visited[i][j] = true; queue<Coords> q; q.push(Coords(i, j)); using Step = pair<ptrdiff_t, ptrdiff_t>; const vector<Step> nearby{ Step(0, +1), Step(0, -1), Step(+1, 0), Step(-1, 0) }; while (!q.empty()) { Coords ij = q.front(); auto i1 = ij.first, j1 = ij.second; q.pop(); for (Step s : nearby) { ptrdiff_t i2 = i1 + s.first, j2 = j1 + s.second; if (get(i2, j2)) { if (!visited[i2][j2]) { visited[i2][j2] = true; q.push(Coords(i2, j2)); } } else { border.insert(BorderPiece(i1, j1, i2, j2)); } } } return border.size(); }
@SergeyTachenov
This seems like a really good approach to me. However I am unclear why the 3rd example has circumference of 5. Shouldn't it be 13 ? Also, i was assuming that with this approach you are going to pad the entire matrix with 0's all around (or at least logically). I am not sure if you have implemented that way. But that would definitely work.
Here is how I solved it:
Key Observation:
In an island how many units can a single 1 contribute ?
0000 0100 0000
In this case the only 1 contributes 4 (= the actual circumference)
0000 0110 0000
In this case the each 1 contributes 3 (the actual circumference = 6)
0000 0110 0010
In this case the two 1's contributes 3 and one of them contributes 2 (the actual circumference = 8)
Lastly,
0010 0111 0010
In this case the all 1's contributes 3 and the middle one contributes 0 (the actual circumference = 12)
Now, contribution for any 1 = max degree (=4) - actual outdegree (You can confirm that from all the examples)
So basically algorithm is :
- Perform dfs/bs
- while visiting each node count its outdegree and compute contribution => add it to total circumference
@ayushpatwari I should have put more dots in there, but the edit function is buggy, and I can't edit now. The thing is, I meant to show only a part of an island, so in the case 3 only the 1s bordering 0s are meaningful, the borders are not borders at all: just imagine one more line of dots below the whole thing.
In my implementation, I did pad the matrix with 0s around: note that the get lambda returns
false in case when
i or
j is outside the area.
Your approach is essentially the same, but without keeping the border pieces in the set. As a matter of fact, I don't have to either! You basically sum up
4 - count of 1s, but it's the same as summing up
count of 0s (assuming the matrix is surrounded by 0s). And that's exactly what I do, so I don't even need a set because I never ever try to insert the same thing into it (because
i1, j1 are unique). Therefore, the size of set will be equal to the number of
insert calls, so I can just count them without actually inserting anything anywhere.
One more interesting observation. The complexity of the whole thing can be up to O(mn). This is the worst case lower bound because in the worst case an island may be a very narrow snake-like windy thing with its circumference of order
mn. But in the best case, when an island has relatively normal shape, we can do much better if we can just go in a random direction, hit the island's border, and then just walk around. It can get as good as O(m + n). It's easier said than done, though, because walking around will involve a lot of edge cases.
This idea raises an important question, though: can an island have “lakes” inside? Because if it can, the improved approach won't work. But then again, our current approach will calculate the total circumference of all shores, both inner and outer, which may or may not be what we want.
On a side note, I think your original problem example has a small mistake: the last case should be (4, 2), not (4, 1) because (4, 1) points to a 0.
I'm not understanding how you guys are counting the perimeter. For example:
01110 00<1>10 11001 01010 ``` The value at (2,3) i've put < > around, if I understand the coordinate system correctly. Now counting the 1's around it, we have: 3 1's in the first row 1 1's in the 2nd row 3 1's in the 3rd row which gives us a total of 7 surrounding ones. How did you arrive at 10? -Thanks
Do BFS or DFS and sum up the number of non diagonally adjacent 0's for every 1 on the island. Edges of the matrix should also be considered as 0's.
@dat.vikash The problem is to find the perimeter, not the number of surrounding one's. I think drawing a diagram and marking out the island will help. Also you can check this problem which was added recently :
Looks like your connection to LeetCode Discuss was lost, please wait while we try to reconnect. | https://discuss.leetcode.com/topic/62098/given-a-0-1-grid-and-coordinates-x-y-find-the-circumference-perimeter-of-the-enclosing-island-of-1-s | CC-MAIN-2017-39 | refinedweb | 1,408 | 72.66 |
Hello! My name is Andrew Jenner and I'm a Software Design Engineer (SDE) in the Visual Studio Devices team. I work on IDE functionality for managed projects (though some of the components I have written are also used by the native project system).
However, for the most part this blog isn't going to be about programming for Smart Devices, programming for the .NET Compact Framework or even .NET programming in general. Instead I'm going to be writing about what I know best - C++ programming techniques, and general programming techniques that can be applied in most languages.
To start off, here's a programming principle that seems to me to be so fundamental that it is often forgotten: Say what you mean.
What do I mean by this? Well, let's start off with a simple example. Suppose you have some code like this:
#include <iostream>
#include <iomanip>
typedef long long int64;
typedef unsigned long long uint64;
struct int128
{
int64 high;
uint64 low;
};
int main()
{
int128 x={10,20}, y={30,40}, z;
z.low = x.low + y.low;
z.high = x.high + y.high;
if (z.low < x.low)
++z.high;
std::cout << std::hex << std::setw(16) << std::setfill('0') << z.high;
std::cout << std::setw(16) << std::setfill('0') << z.low << std::endl;
}
What does this code actually do? Well, it may not be obvious at first sight because it doesn't actually say what it does. But compare this slightly modified version:
int128 sum_of_128bit_numbers(int128 x,int128 y)
{
int128 z;
z.low = x.low + y.low;
z.high = x.high + y.high;
if (z.low < x.low)
++z.high;
return z;
}
z = sum_of_128bit_numbers(x,y);
Now we can immediately see that this code implements addition of high precision integers. The simple act of naming the 4 mysterious lines of code (by putting them in a function with a descriptive name) has made the program much easier to understand (more so, I would argue, than an equivalent comment that just explains what those 4 lines of code do).
This change doesn't make any difference to the compiler (especially if it implements Named Return Value Optimization or chooses to inline the sum_of_128bit_numbers() function) but it greatly improves the readability of the program for humans. It's easy to write a program that a computer can understand (just change things until it compiles) but writing programs that are easy for people to understand is much more difficult. Since any non-trivial program will eventually need to be maintained, we should strive to make all our code as easy to read by humans as possible. | http://blogs.msdn.com/ajenner/archive/2004/07/29/201165.aspx | crawl-002 | refinedweb | 438 | 61.97 |
Add a feature layer
Learn how to use a URL to access and display a feature layer in a map.
A map contains layers of geographic data. A map contains a basemap layer and, optionally, one or more data layers. This tutorial shows you how to access and display a feature layer in a map. You access feature layers with an item ID or URL. You will use URLs to access the Trailheads, Trails, and Parks and Open Spaces feature layers and display them in a map.
A feature layer is a dataset in a feature service hosted in ArcGIS. Each feature layer contains features with a single geometry type (point, line, or polygon), and a set of attributes. You can use feature layers to store, access, and manage large amounts of geographic data for your applications.
In this tutorial, you use URLs to access and display three different feature layers hosted in ArcGIS Online: a Visual Studio solution
To start the tutorial, complete the Display a map. This is not required, your code will still work if you keep the original name. The instructions will refer to
Add rather than
Display.
Update the name for the solution and the project.
- In the Visual Studio > Solution Explorer, right-click the solution name and choose Rename. Name the solution
Add.
AFeature Layer
- In the Solution Explorer, right-click the project name and choose Rename. Name the project
Add.
AFeature Layer
Update the name of the namespace used by classes in the project.
- In the Solution Explorer, expand the project node.
- Double-click
Mapin the Solution Explorer to open the file.
View Model.cs
- In the
Mapclass, double-click the namespace name (
View Model
Display) to highlight it, right-click and choose Rename....
AMap
- Rename the namespace
Add.
AFeature Layer
- Click Apply in the Rename: DisplayAMap window that appears in the upper-right of the code window. This will rename the namespace throughout your project.
Build the project.
- Choose Build > Build solution (or press <F6>).
Create URIs to reference feature service data
To display three new data layers (also known as operational layers) on top of the current basemap, you will create
FeatureLayers using URIs to reference datasets hosted in ArcGIS Online.
Open a browser and navigate to the URL for Parks and Open Spaces to view metadata about the layer. To display the layer in your ArcGIS Runtime app, you only need the URL.
The service page provides information such as the geometry type, the geographic extent, the minimum and maximum scale at which features are visible, and the attributes (fields) it contains. You can preview the layer by clicking on ArcGIS.com Map in the "View In:" list at the top of the page.
In the Visual Studio > Solution Explorer, double-click MapViewModel.cs to open the file.
The project uses the Model-View-ViewModel (MVVM) design pattern to separate the application logic (view model) from the user interface (view).
Mapcontains the view model class for the application, called
View Model.cs
Map. See the Microsoft documentation for more information about the Model-View-ViewModel pattern.
View Model
In the
Setupfunction, add code that defines the URIs to the hosted layers. You will add: Trailheads (points), Trails (lines), and Parks and Open Spaces (polygons).
Map() Expand Use dark colors for code blocks Add line. Add line. Add line. Add line. Add line. Add line. Add line. Add line. Add line. Add line. Add line.
private void SetupMap() { Map = new Map(BasemapStyle.ArcGISTopographic); var parksUri = new Uri( "" ); var trailsUri = new Uri( "" ); var trailheadsUri = new Uri( "" );
Expand
Create feature layers to display the hosted data
You will create three new
FeatureLayer to display the hosted layer at each URI.
In the
Setupfunction, create new feature layers and pass the appropriate URI to the constructor for each.
Map() Expand Use dark colors for code blocks Add line. Add line. Add line.
var trailheadsUri = new Uri( "" ); var parksLayer = new FeatureLayer(parksUri); var trailsLayer = new FeatureLayer(trailsUri); var trailheadsLayer = new FeatureLayer(trailheadsUri);
Expand
Add the feature layers to the map. Data layers are displayed in the order in which they are added. Polygon layers should be added before layers with lines or points if there's a chance the polygon symbols will obscure features beneath.
Expand Use dark colors for code blocks Add line. Add line. Add line.
var parksLayer = new FeatureLayer(parksUri); var trailsLayer = new FeatureLayer(trailsUri); var trailheadsLayer = new FeatureLayer(trailheadsUri); Map.OperationalLayers.Add(parksLayer); Map.OperationalLayers.Add(trailsLayer); Map.OperationalLayers.Add(trailheadsLayer);
Expand
Click Debug > Start Debugging (or press <F5> on the keyboard) to run the app.
You should see point, line, and polygon features (representing trailheads, trails, and parks) draw on the map for an area in the Santa Monica Mountains.
What's next?
Learn how to use additional API features, ArcGIS location services, and ArcGIS tools in these tutorials: | https://developers.arcgis.com/net/layers/tutorials/add-a-feature-layer/ | CC-MAIN-2022-40 | refinedweb | 809 | 56.35 |
Heads up! To view this whole video, sign in with your Courses account or enroll in your free 7-day trial. Sign In Enroll
Preview
An Update Action5:52 with Jay McGavren
We've successfully created a form for editing an existing Page, and populated it with the Page's attributes. But if we submit the form, we see that a so-called HTTP PATCH request is being sent by the browser, and there's no route for that type of request. So to process these requests, we'll need to go into routes.rb add a PATCH route.
A controller action to update an existing model object usually performs these operations:
def update # Look up the existing model record based # on an ID from the request path. @page = Page.find(params[:id]) # Filter the form parameters to ensure no # malicious parameters were added. page_params = params.require(:page).permit(:title, :body, :slug) # Use the filtered parameters to update # the existing model record. @page.update(page_parameters) # Redirect the browser to another location # so that it doesn't just sit there displaying # the submitted form. redirect_to @page end
We've successfully created a form for editing and the existing page and 0:00
populated it with the pages attributes, but if we submit the form, 0:04
we see that the so-called HTTP patch request is being sent by the browser and 0:08
there's no route for that type of request. 0:12
When you're modifying existing data on the server rather than adding new data, 0:15
you're supposed to use a put or patch request rather than a post request. 0:19
So when you click the submit button on the edit form, 0:24
that's what your browser sends to the server, a patch request. 0:26
Actually, it's technically still a post request coming for the browser but 0:30
it has some added parameters indicating it should be treated as a patch request and 0:34
Rails converts the request type to patch internally. 0:38
So to process these requests we'll need to go into routes.rb and add a patch route. 0:41
Just as we use the get method for get routes and the post method for 0:46
post routes, we call the patch method to create a patch route. 0:49
We can do it here at the bottom of the list, the order doesn't matter. 0:54
Let's go to our browser and look at the HTML for the edit form. 0:57
We can see that its action attribute is set to submit to a path of pages 1:02
followed by the page ID. 1:06
The ID is provided so that we can look the record up in the database just like we do 1:08
with the show and edit pass. 1:12
Once we found the record in the database we can use the form parameters 1:14
to update it. 1:17
So that's the path we use in our route slash pages followed by another slash and 1:19
an ID parameter. 1:25
We'll direct all matching requests to the pages controllers, Update method. 1:27
Save our work and now we need to define that update method on the controller. 1:35
So we'll go app controllers, pages controller and 1:39
we'll add an update method here at the bottom. 1:44
We'll start by using the ID parameter to look up the model object 1:49
just like we do in the show and edit it actions. 1:52
We'll sign it to a page instance variable and we'll 1:54
call a page.find params id, taking the parameter from the URL. 2:00
After that, the code for 2:07
our update method will look very similar to the code in our create method. 2:08
We will create a page params variable to hold our filtered list parameters and 2:13
then we'll take our params object. 2:17
We'll require the page parameter and will permit 2:20
title body and slug parameters. 2:28
Instead of passing those parameters to page.new to create a new page, 2:34
we'll pass them to the update method on the page object that we loaded in. 2:38
So we'll take our page object and we'll call update and 2:43
we'll pass it a filtered set of parameters. 2:47
That will update all the objects attributes with the parameters from 2:52
the form and then automatically save it. 2:55
Finally, just like in the create method we'll redirect the browser to view 2:58
the updated page. 3:01
Now if we visit an edit form in our browser, modify the page. 3:08
And then submit it the result will be saved. 3:19
There's one more small thing we need to fix before we wrap up the stage. 3:28
We've already talked about the dry principle, 3:33
don't repeat yourself as it relates to partial templates. 3:35
But the same is true for your Ruby code. 3:38
We have identical code in our create an update methods to require some form of 3:41
parameters and permit others. 3:45
But what if you added a new attribute? 3:47
You might permit it in the create method but 3:49
forget to do the same in the update method. 3:51
Suddenly your new page form would work correctly but 3:53
your edit page form wouldn't. 3:56
It would be better to have a single copy of that code that's utilized by 3:58
both the create and update methods. 4:01
That's why a code for requiring imprinting parameters is frequently 4:03
placed in a separate method within the controller. 4:07
Other methods such as create an update can just call this parameters method and 4:09
use its return value to create or update model objects. 4:13
All we have to do is move the code that requires and 4:17
permits parameters to a new method. 4:19
We'll name the method page params, 4:21
just like the variable we were assigning to in the create an update methods. 4:24
We'll paste our code in and 4:30
then we can delete the assignments to the page param's variable. 4:32
References of the page_params variable will not simply be treated as if they were 4:37
a call to the page_params method. 4:41
The page_params method returns a parameters object and 4:44
those parameters will be used to create or update page objects. 4:48
The page_params method should only be used inside the pages control or class so 4:53
it's probably best marked method private so no one else attempts to call it. 4:59
One way to mark it private is to put the private keyword before it. 5:03
All methods defined following the private keyword will then be marked private. 5:07
Many developers like to indent those methods an extra level so 5:11
that it's clear they are private. 5:15
Let's go back to our browser and test the parameters will still work for a new page. 5:17
They do, and will try editing the save page as well. 5:24
Works just fine. 5:32
That's another feature finished. 5:35
You created an edit control erection the presents a form pre-populated 5:37
with an existing model objects data. 5:41
Then you added an update action that accepts the form parameters and 5:43
updates the model object. 5:47
One stage to go and it will be short and sweet see you there. 5:49 | https://teamtreehouse.com/library/an-update-action?t=335 | CC-MAIN-2021-04 | refinedweb | 1,343 | 69.41 |
Member
29 Points
Apr 09, 2015 01:52 AM|lucky7456969|LINK
I have uploaded anything, the program is up and running.
But.... The CalendarExtender is not working, no dropdowns for the calendar.
I've uploaded the AJAXControlTookKit.dll to the bin folder.
Everything else, aspx, js, css, Global.asax, master page, my application.publish.xml and web.config as usual.
Everything is up and running except the CalendarExtender is not there.
Resources up'ed (pngs)
What may be the reasons why the CalendarExtender is not showing when being clicked on the date textbox...
Double checked all the files are present...
Contributor
2106 Points
Apr 09, 2015 02:30 AM|Nadeem157|LINK
lucky7456969What may be the reasons why the CalendarExtender is not showing when being clicked on the date textbox...
The reason may be:-
To see an error with the ajax control toolkit, debug in internet explorer. Once I stopped debugging in chrome, I caught an error that said:
...AjaxControlToolkit requires ASP.NET Ajax 4.0 scripts.
I had to remove
Microsoft.Scriptmanager.MSAjax.dll from the bin folder of the project.
Also
do you have registered the tagPrefix and the assembly in your web.config? Like below
<system.web> <pages> <controls> <add tagPrefix="asp" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/> </controls> </pages> </system.web>
In the below link, you will get all the documents related to AjaxControlToolkit.
AjaxControlToolkit tutorial
Member
29 Points
Apr 09, 2015 03:00 AM|lucky7456969|LINK
Tried that... Doesn't work
I notice I am using System Web Extension Version 4.0.0.0
and AJAXControlToolKit version 3.0.20820.16598
and Runtime version 2.0.50727
Is there going to be a problem?
Thanks
Jack
Contributor
2106 Points
Apr 09, 2015 03:12 AM|Nadeem157|LINK
Yes,
Do one thing,
Uninstall the AjaxToolkit.
Again download it from the link below
Then, install in your project. It will automatically add the proper version in the web.config file.
3 replies
Last post Apr 09, 2015 03:12 AM by Nadeem157 | https://forums.asp.net/t/2044541.aspx?What+might+be+the+possibilities+of+AJAXToolkit+not+working+under+aspspider+net+ | CC-MAIN-2019-09 | refinedweb | 345 | 62.14 |
Created on 2009-02-02 19:57 by paul.moore, last changed 2013-06-07 20:09 by lukasz.langa. This issue is now closed.
This patch takes the existing "simplegeneric" decorator, currently an
internal implementation detail of the pkgutil module, and exposes it as
a feature of the functools module.
Documentation and tests have been added, and the pkgutil code has been
updated to use the functools implementation.
Open issue: The syntax for registering an overload is rather manual:
def xxx_impl(xxx):
pass
generic_fn.register(XXX, xxx_impl)
It might be better to make the registration function a decorator:
@generic_fn.register(XXX)
def xxx_impl(xxx):
pass
However, this would involve changing the existing (working) code, and I
didn't want to do that before there was agreement that the general idea
(of exposing the functionality) was sound.
PJE seems to have borrowed the time machine :-). Based on the code the
register function is already a decorator:
def register(typ, func=None):
if func is None:
return lambda f: register(typ, f)
registry[typ] = func
return func
The returned lambda is a one argument decorator. so your syntax:
@generic_fn.register(XXX)
def xxx_impl(xxx):
pass
Already works. A test to validate this behavior should probably be added.
I don't mean to bikeshed, but could we call this function
functools.generic instead of functools.simplegeneric? The only reason I
can think of for keeping it simplegeneric would be to avoid a future
name clash with the Generic Function PEP and if/when that PEP get's
implemented, I would think that the functionality would live in
builtins, not functools.
Well spotted! I missed that when I checked. I will add tests and
documentation.
I agree that generic is better. I only left it as it was because the
original intent was simply to move the existing code - but that's not a
particularly good reason for keeping a clumsy name. There shouldn't be a
clash, as any more general mechanism can either be in its own module or
the existing function can be extended in a compatible manner. I'll make
this change too.
Thanks for the feedback!
Here's an updated patch.
The reason I like the simplegeneric name is that that is exactly what
this feature is: a *simple* generic implementation that is deliberately
limited to dispatching on the first argument (because that is easily
explained to users that are already familiar with OOP and especially the
existing Python magic method dispatch mechanism.
So the name isn't just about avoiding name clashes, it's also about
setting appropriate expectations as to what is supported. Yes, the name
is a little clumsy but one thing I do *not* want to see happen is a
swathe of feature requests asking that this become an all-singing
all-dancing generic function mechanism like RuleDispatch.
Don't forget that actually *writing* generic functions (i.e. using the
@functools.simplegeneric decorator itself) should be far less common
than using the .register() method of existing generic functions..
The patch looks fine to me. Tests pass.
I have no opinion about the name. Both "simplegeneric" and "generic" are
OK to me.
I wonder if being able to use register() directly instead of as a
decorator should be dropped.
Also IMHO the Python 2.3 backwards compatibility (__name__ isn't
setable) can be dropped.
Agreed about the compatibility. It's there from pkgutil, where to be
honest, it's even less necessary, as simplegeneric was for internal use
only, there. I'm certainly not aware of any backward compatibility
requirements for functools.
Assuming nobody speaks up to the contrary, I'll rip out the
compatibility bits in the next version of the patch.
I'm unsure about the non-decorator version of register. I can imagine
use cases for it - consider pprint, for example, where you might want to
register str as the overload for your particular type. But it's not a
big deal either way.
I think that registering existing functions is an important use case, so
I vote for keeping the non-decorator version of register.
Another thing that we may want to document is that [simple]generic
doesn't dispatch based on registered abstract base classes.
>>> class A:
... pass
...
>>> class C:
... __metaclass__ = abc.ABCMeta
...
>>> C.register(A)
>>> @generic
... def pprint(obj):
... print str(obj)
...
>>> @pprint.register(C)
... def pprint_C(obj):
... print "Charlie", obj
...
>>> pprint(C())
Charlie <__main__.C object at 0xb7c5336c>
>>> pprint(A())
<__main__.A instance at 0xb7c5336c>
Failure to respect isinstance() should be fixed, not documented :)
As far as registering existing functions goes, I also expect registering
lambdas and functools.partial will be popular approaches, so keeping
direct registration is a good idea. There isn't any ambiguity between
the one-argument and two-argument forms.
Agreed (in principle). However, in practice the subtleties of override
order must be documented (and a method of implementation must be
established!!!) Consider:
>>> class A:
... pass
...
>>> class C:
... __metaclass__ = abc.ABCMeta
...
>>> class D:
... __metaclass__ = abc.ABCMeta
...
>>> C.register(A)
>>> D.register(A)
>>> @generic
... def pprint(obj):
... print "Base", str(obj)
...
>>> @pprint.register(C)
... def pprint_C(obj):
... print "Charlie", obj
...
>>> @pprint.register(D)
... def pprint_D(obj):
... print "Delta", obj
...
>>> pprint(A())
What should be printed? A() is a C and a D, but which takes precedence?
There is no concept of a MRO for ABCs, so how would the "correct" answer
be defined? "Neither" may not be perfect, but at least it's clearly
defined. Relying on order of registration for overloads of the generic
function seems to me to be unacceptable, before anyone suggests it, as
it introduces a dependency on what order code is imported.
So while the theory makes sense, the practice is not so clear.
Respecting ABCs seems to me to contradict the "simple" aspect of
simplegeneric, so a documented limitation is appropriate.
(But given the above, I'm more inclined now to leave the name as
"simplegeneric", precisely to make this point :-))
Hmm, there is such a thing as being *too* simple... a generic function
implementation that doesn't even respect ABCs seems pretty pointless to
me (e.g. I'd like to be able to register a default Sequence
implementation for pprint and have all declared Sequences use it
automatically if there isn't a more specific override).
I'll wait until I have a chance to actually play with the code a bit
before I comment further though.
Very good point. Registering for the standard ABCs seems like an
important use case. Unfortunately, it seems to me that ABCs simply don't
provide that capability - is there a way, for a given class, of listing
all the ABCs it's registered under? Even if the order is arbitrary,
that's OK.
Without that, I fail to see how *any* generic function implementation
("simple" or not) could support ABCs. (Excluding obviously broken
approaches such as registration-order dependent overload resolution).
The problem is that ABCs are all about isinstance testing, where generic
functions are all about *avoiding* isinstance testing. (As a compromise,
you could have a base generic function that did isinstance testing for
the sequence ABC).
Even more inconveniently, the existence of unregister() on ABCs makes it
difficult for the generic to cache the results of the isinstance()
checks (you don't want to be going through the chain of registered ABCs
every time calling isinstance(), since that would be painfully slow).
That said, it is already the case that if you only *register* with an
ABC, you don't get any of the methods - you have to implement them
yourself. It's only when you actually *inherit* from the ABC that the
methods are provided "for free". I guess the case isn't really any
different here - if you changed your example so that A inherited from C
and D rather than merely registering with them, then C & D would appear
in the MRO and the generic would recognise them.
So perhaps just documenting the limitation is the right answer after all.
Here's an updated patch. I've reverted to the name "simplegeneric" and
documented the limitation around ABCs (I've tried to give an explanation
why it's there, as well as a hint on now to work around the limitation -
let me know if I'm overdoing it, or the text needs rewording).
I've also fixed the wrapper to use update_wrapper to copy the
attributes. That way, there's no duplication.
Unassigning - the lack of support for ABC registration still bothers me,
but a) I don't have a good answer for it, and b) I'm going to be busy
for a while working on some proposed changes to the with statement.
The problem with generic functions supporting ABCs is it's a bug with
the way ABCs work and not a problem with the generic function
implementation. it's MRO. It's not a
base class if it's not in the MRO!
The documentation for lack of ABC support should read something like:
+ Note that generic functions do not work with classes which have
+ been declared as an abstract base class using the
+ abc.ABCMeta.register() method because this method doesn't make
+ that abstract base class a base class of the class - it only fakes
+ out instance checks.
Perhaps a bug should be opened for the abc.ABCMeta.register() method.
However, I'd say that just because virtual abstract base classes are
wonky doesn't mean that a solid generic function implementation
shouldn't be added to standard library.
I raised issue 5405. Armin Ronacher commented over there that it's not
even possible in principle to enumerate the ABCs a class implements
because ABCs can do semantic checks (e.g., checking for the existence of
a special method).
So documenting the limitation is all we can manage, I guess.
Given the point Armin raised, I once again agree that documenting the
limitation is a reasonable approach. Longer-term, being able to subcribe
to ABCs (and exposing the registration list if it isn't already visible)
is likely to be the ultimate solution.
Please don't introduce this without a PEP.
Changes as Guido has stated that he wants a PEP.
I don't propose to raise a PEP myself. The issue with ABCs seems to me to be a fundamental design issue, and I think it's better to leave raising any PEP, and managing the subsequent discussion, to someone with a deeper understanding of, and interest in, generic functions.
Not sure if the lack of a champion means that this issue should be closed. I'm happy if that's the consensus (but I'm also OK with it being left open indefinitely, until someone cares enough to pick it up)..
An elaborate PEP for generic functions already exists, PEP 3124 []. Also note the reasons for
deferment. I'd be interested in creating a "more limited" generic function
implementation based on this PEP, minus func_code rewriting and the other
fancier items. Sadly I won't have any bandwidth to work on it until January
of next year.
I'd vote for keeping this issue open because of that.
On Thu, Jul 22, 2010 at 5:45 AM, Antoine Pitrou <report@bugs.python.org>wrote:
>
> Antoine Pitrou <pitrou@free.fr> added the comment:
>
>.
>
> ----------
> nosy: +pitrou
>
> _______________________________________
> Python tracker <report@bugs.python.org>
> <>
> _______________________________________
>
A couple more relevant links.
I brought this issue up in the context of a JSON serialisation discussion on python-ideas:
Andrey Popp mentioned his pure Python generic functions library in that thread:
> [its] MRO.
I disagree. If someone writes a class and registers them with an ABC, it is their duty to make sure that the class actually complies. Virtual subclasses are provided for use by consenting adults IMO.
Just as an FYI, it *is* possible to do generic functions that work with Python's ABCs (PEAK-Rules supports it for Python 2.6), but it requires caching, and a way of handling ambiguities. In PEAK-Rules' case, unregistering is simply ignored, and ambiguity causes an error at call time. But simplegeneric can avoid ambiguities, since it's strictly single-dispatch. Basically, you just have two dictionaries instead of one.
The first dictionary is the same registry that's used now, but the second is a cache of "virtual MROs" you'll use in place of a class' real MRO. The virtual MRO is built by walking the registry for classes that the class is a subclass of, but which are *not* found in the class's MRO, e.g.:
for rule_cls in registry:
if issubclass(cls, rule_cls) and rule_cls not in real_mro:
# insert rule_cls into virtual_mro for cls
You then insert those classes (abcs) in the virtual MRO at the point just *after* the last class in the MRO that says it's a subclass of the abc in question.
IOW, you implement it such that an abc declaration appears in the MRO just after the class that was registered for it. (This has to be recursive, btw, and the MRO cache has to be cleared when a new method is registered with the generic function.)
This approach, while not trivial, is still "simple", in that it has a consistent, unambiguous resolution order. Its main downside is that it holds references to the types of objects it has been called with. (But that could be worked around with a weak key dictionary, I suppose.) It also doesn't reset the cache on unregistration of an abc subclass, and it will be a bit slower on the first call with a previously-unseen type.
The downside of a PEP, to me, is that it will be tempting to go the full overloading route -- which isn't necessarily a bad thing, but it won't be a *simple* thing, and it'll be harder to get agreement on what it should do and how -- especially with respect to resolution order.
Still, if someone wants to do a PEP on *simple* generics -- especially one that can replace pkgutil.simplegeneric, and could be used to refactor things like copy.copy, pprint.pprint, et al to use a standardized registration mechanism, I'm all in favor -- with or without abc registration support.
Btw, the current patch on this issue includes code that is there to support classic classes, and metaclasses written in C. Neither should be necessary in 3.x. Also, a 3.x version could easily take advantage of type signatures, so that:
@foo.register
def foo_bar(baz: bar):
...
could be used instead of @foo.register(bar, foo_bar).
But all that would be PEP territory, I suppose.
Thanks for the detailed explanation. Note that type annotations are disallowed in the stdlib, as per PEP 8.
Guido said "Please don't introduce this without a PEP." and that has not happened and if it did, the result would probably look quite different from the patches. So this is 'unripe' and no current action here is possible.
For the record, this has been implemented as PEP 443. | http://bugs.python.org/issue5135 | CC-MAIN-2015-48 | refinedweb | 2,508 | 64 |
All-Star
47060 Points
Moderator
MVP
May 20, 2011 03:46 AM|HeartattacK|LINK
Model binding can automatically hook up query string parameters if routing correctly. And you can also access query string values by doing Request["keyName"] just as in webforms.
Participant
830 Points
May 20, 2011 04:16 AM|Dhaval Tawar|LINK
If you have mapped querystring in your routetable then you can get it from ViewContext.RouteData["key"] else Request.QueryString["key"]
e.g.
<%= Html.ActionLink("Link Text", "action", "controller", new { id = "1", page = "2" }, new { @class = "linkclass" }) %>
Here if you have mapped id like
routes.MapRoute(
"Default", // Route name
"{controller}/{action}/{id}", // URL with parameters
new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults
);
you can get it using ViewContext.RouteData["id"].
But you have not mapped page. So you can get it using Request.QueryString["page"]
Contributor
3574 Points
May 20, 2011 04:39 AM|krokonoster|LINK
Quite simple, and thanks to the magic of modelbinding not much that you have to do.
QueryString values along with id parameter in ASP.NET MVC
I (and most other's i believe, rather prefer route data (people/get/1 vs people/get?id=1)
Member
348 Points
May 20, 2011 10:22 AM|joelkronk@hotmail.com|LINK
Is there any way you can give us specific details on what you're trying to accomplish exactly? there are a million uses for query strings and just as many ways to send data into and get data out of a query string. More details would help hone down the variety of answers you are going to get for this type of question.
Thanks!
All-Star
46414 Points
May 20, 2011 01:13 PM|bruce (sqlwork.com)|LINK
if you want to send query string mycontroller/action?a=1&b=2&c=hello
then in the controller its:
public ActionResult action(int a, int b, string c)
or
public class qModel { public int a {get; set;} public int b {get; set;} public string c {get; set;} } public ActionResult action (qModel model) { ... }
5 replies
Last post May 20, 2011 01:13 PM by bruce (sqlwork.com) | https://forums.asp.net/t/1682546.aspx | CC-MAIN-2017-30 | refinedweb | 356 | 64.61 |
This is your resource to discuss support topics with your peers, and learn from each other.
01-08-2013 01:06 PM
Hey all,
i created a class with some properties.
Now i want to add objects of this class to a DataModel and show the properties in a ListView.
A simple Example:
class CustomClass { QString name; QString age; QString something; }
I create the ListView in Qml, define listItemComponents.
ListView { id: list objectName: "list" dataModel: ArrayDataModel {} listItemComponents: [ ListItemComponent { Container { id: itemContainer Label { Text: itemContainer.ListItem.data.name } Label { Text: itemContainer.ListItem.data.age } } } ] }
in c++, i use findchild to get the ListView.
Now the problem begins, i dont know how to get my objects into the datamodel.
You can only add QVariants to the model.
So i tried creating a QVariant and used its setValue() function to add my CustomClass object.
But when i start my app, i get the error: Unable to assign [undefined] to QString and no data is shown.
If i assign String(itemContainer.ListItem.data) to the Label.Text, is see the classname of my class, so the objects seem to be there.
I also tried defining the propertys as Q_PROPERTYS and used Q_DECLARE_METATYPE() but nothing helped.
Maybe someone has an idea what im doing wrong.
Gretings.
Solved! Go to Solution.
01-08-2013 01:19 PM
Hi,
you have a lot ways to populate a listView from C++. I think the best you can do now is to read the cascades tutorial article about DataModels:
cheers,
chriske
01-08-2013 01:28 PM
Here is an official BB example, it uses the type of custom c++ list item component what you want:
01-09-2013 04:46 AM
Hey chriske,
thans for your answers.
I've read the articles about Datamodels.
I don't want to group items and i dont have an xml structure.
So i could use ArrayDataModel, but i cant add my data (CustomClass) to this DataModel because its no QVariant.
I used Q_DECLARE_METATYPE(CustomClass); and QVariant::fromValue(customObj) to fill the ArrayDataModel with my objects.
If i now assign the ListItemData to a Label.Text property, it shows CustomClass as Text.
But if i assign ListItemData.name to it, i get "Unable to assign [undefined]".
Maybe i'm missing something
01-09-2013 07:43 AM - edited 01-09-2013 07:45 AM
Hi,
I have a solution for you. I've created a simple class:
class CustomElement : QObject { Q_OBJECT public: CustomElement(QObject* parent); virtual ~CustomElement(); QString getCode(); QString getName(); void setCode(QString aCode); void setName(QString aName); private: QString code; QString name; };
Added a listView to QML:
ListView { objectName: "list" listItemComponents: [ ListItemComponent { //type: "listItem" Container { id: itemRoot Label { text: ListItemData.code } Label { text: ListItemData.name } } } ] }
And defined the look of the list items with ListItemComponent. A single list item contains 2 Labels. One for code and one for name.
On C++ side, I initialize first a QList from CustomElement* .
In header: QList<CustomElement*> list; In cpp: for (int i = 0; i < 20; i++) { CustomElement* element = new CustomElement(this); element->setCode(QString::number(i)); element->setName("name " + QString::number(i)); list << element; }
And the here comes the "magic". If you don't want to use Q_Properties, the best option you have is QVariantListDataModel. You can assign this class to the listView's model directly. Definition:
#include <bb/cascades/QListDataModel> bb::cascades::QVariantListDataModel listModel;
You must fill this object with QVariantMap objects. I'll show you how to do this:
QVariantMap map = QVariantMap(); for (int i = 0; i < 20; i++) { map["code"] = list.at(i)->getCode(); map["name"] = list.at(i)->getName(); listModel << map; } ListView* listView = root->findChild<ListView*>("list"); listView->setDataModel(&listModel);
This code-snippet is started after this lines:
// set created root object as a scene app->setScene(root);
So, QVariantMap can hold the name of a property, and it's value too.
So, filling with data is very simple.
I've tested it, and works like a charm | https://supportforums.blackberry.com/t5/Native-Development/Fill-dataModel-with-CustomObjects-and-show-in-a-ListView/m-p/2083849/highlight/true | CC-MAIN-2017-09 | refinedweb | 659 | 57.77 |
Introduction
The Deployment Architecture Tools included in the IBM® Rational® Software Architect solution come with a set of predefined technology domains to enable the planning of application deployments. Due to the vast amount of software, middleware, and hardware domains in existence today, the need for an extension to the platform arises.
A simple way to extend the available units is to copy and rename generic units, such as Generic Software units. This approach is often sufficient if the topology editor is only to be used for deployment modeling, and no further transformations from the modeled topology need to be created. However, if the modeled topology will be the basis for additional transformations (e.g. configuration files or installation scripts), this approach is insufficient, because the resulting XML representation of the topology is too generic and the extended elements can only be identified by naming conventions, which can be ambiguous and not overly robust. To obtain strong XML types in a serialized topology, you must create a formal domain in the platform. The Topology Domain Generation Toolkit provides a straightforward way of creating custom technology domains with strong XML types in the topology file.
In this tutorial, we present a real world scenario and show an easy to use extension mechanism for the topology editor, which lets you quickly define your own technology domain with strong XML types.
There are two appendices for this article:
Extending the Deployment Architecture Platform
The overall scenario of this tutorial is to model the planning of an application deployment for a MySQL database, which is not one of the domains provided with your Rational Software Architect toolset. These domains include DB2, Derby, and generic database units, but not MySQL.
A superficial way of creating a new kind of unit is to copy an existing unit and give it a caption that suggests that it is a different type of unit. For example, you might rename a generic database unit to appear to be a MySQL database, as in Figure 1.
Figure 1. Creating new units by relabeling existing units
However, this strategy creates units that merely look like MySQL database components; the units themselves retain the type and attributes of the original units from which they were created. You could make other changes to the unit to indicate its differences, such as applying a custom style or appearance to the unit, but these changes are all superficial; the unit type does not change.
A better way to model a new type of unit such as a MySQL database is to create a MySQL database system unit with the specific properties of that software component. To ease the creation of the initial domain model, and to ensure maximum reusability for the new types, you can leverage existing model constructs where they are available.
To extend the Deployment Architecture Platform with your own technology domain, the following steps are necessary:
- Install the Topology Domain Generation Toolkit.
- Create an XML Schema Definition for the new technology domain. This schema definition defines the desired metamodel of the new technology domain, including the types of units and capabilities that are available in the domain.
- Generate the plug-in code into a form that can be used by IBM Rational Software Architect.
Prerequisites
This tutorial assumes a basic familiarity with topologies and the deployment architecture tools. For links to introductory material on these topics, see the Resources section.
To work through these instructions, you need IBM® Rational® Software Architect Version 7.5.5 or later and the Topology Domain Generation Toolkit. The steps for installing the toolkit are slightly different for Rational Software Architect V7.5 and V8.0.
Install the Topology Domain Generation Toolkit (Rational Software Architect V7.5)
- Download the Topology Domain Generation Toolkit Version 7.5 from the Downloads section, and extract it to a temporary folder on your computer. This file contains a feature that you must install into your Eclipse workbench.
- From the menu bar of the workbench, click Help > Software Updates.
- At the Software Updates and Add-ons window, go to the Available Software tab, click Add Site, click Local, and browse to the directory where you extracted the SDK feature (see Figure 2).
Figure 2. Add the Topology Generation Toolkit update site
- Select the Domain Generation Feature and then click Install.
- Complete the Installation Wizard process and restart the workbench (see Figure 3).
Figure 3. Install the domain generation feature
Install the Topology Domain Generation Toolkit (Rational Software Architect V8.0 and later)
-.
Create the domain extension
The files that define the domain are contained in an Eclipse project. Later, this tutorial will show you how you can package this project to share it with other people who might want to use your custom domain.
- To get the workbench ready to create the domain extension, switch to the Plug-in Development perspective and enable the XML Developer capability. Click Window > Open Perspective > Other and double-click Plugin Development. Then click Window > Preferences; General > Capabilities, select the XML Developer check box, and click OK.
- Create an empty project in your IBM Rational Software Architect (File > New > Project; General > Project) and name it "org.example.mysql".
- Add a folder named "model" to the new project and create two additional folders under "model" named "ecore" and "schema". These will be the locations of our model constructs. Now the project looks like Figure 4.
Figure 4. Initial project structure
- Inside the "schema" folder, create a new XML Schema Definition, which is the starting point for domain extensions and which contains the initial model elements for your technology domain extension.
- Right-click on the "schema" folder and select "New > Other" from the context menu.
- In the New window, select Example EMF Model Creation Wizards > XSD Model. (If you don't see Example EMF Model Creation Wizards, select the Show All Wizards check box at the bottom of the wizard.)
- Click Next and name the schema file "mysql.xsd" and click Next again. (If you had to select the Show All Wizards check box, a popup window asks if you want to enable the Eclipse Modeling Framework capability; if you see this window, click OK.)
- In the following dialog (see Figure 5), specify the initial settings for the XSD Model. Here, set the Target Namespace Prefix to "mysql" and the Target Namespace to. The target namespace defines the unique identifier for the XML schema file and its domain extension.
- Click Finish. The XSD file is created and the XSD editor opens in the workspace.
- Select the Source tab of the editor in order to edit the contents of the XSD in text mode.
Figure 5. Initial settings of the mysql.xsd file
- Edit the file as shown in Listing 1 by adding the namespaces for the "ecore" and "core" domain and by annotating the XSD file with ecore attributes. The ecore information is required for the transformation process and the value of the attribute
ecore:nsPrefixwill later be used as the namespace prefix for your own domain extension. The namespace "core" refers to basic element definitions of the topology editor and is later required to derive your own units and capabilities. In order to access the elements of the core schema, its location has to be provided in a XSD import declaration.
Listing 1. Initial XML schema file for the domain extension
<?xml version="1.0" encoding="UTF-8" standalone="no"?> <xsd:schema xmlns: <xsd:import <!-- unit and capability definitions go here --> </xsd:schema>
Adding a unit to the domain
As a next step, you will define a new topology element (in this case, a unit), which represents the MySQL database in a topology and which will appear in the palette of the topology editor. Each new topology element needs two elements in the XSD file: an xsd:element element that declares the unit type and an xsd:complexType element that defines the supertype and attributes of the unit type.
The first XSD element contains the following information:
- The name of the new diagram element.
- The attribute substitutionGroup, which specifies the kind of topology element for the new element, such as a unit or a capability. For units, this attribute is set to "core:unit"; for capabilities, this attribute is set to "core:capability".
- The reference to the type definition. You can use the same type for more than one unit, but it's usually easiest to define a new type for each unit.
The unit declaration for the MySQL database system looks like the code in Listing 2:
Listing 2: Unit declaration snippet
<xsd:element
The type definition in the xsd:complexType element specifies the supertype for the unit and any additions to that supertype. For the supertype, you can refer to the general types "Unit" or "SoftwareComponent" defined in the "core" schema, or you can refer to a more specific unit in another predefined domain. In the latter case, you must import the domain specification (namespace declaration and XSD import declaration with the schema location) so that the XSD parser can resolve the referred elements.
In the case of our MySQL example, we can derive our new element from the existing unit "DatabaseSystemUnit" from the database domain, which defines the generalized concept of a database management system. The unit type definition looks like the code in Listing 3:
Listing 3: Unit type definition snippet
<xsd:complexType <xsd:complexContent> <xsd:extension </xsd:complexContent> </xsd:complexType>
This type definition refers to a unit in the database domain, so you must add the namespace declaration and the import declaration for the database domain from Listing 4 to your XSD. This snippet includes a new attribute to be added to the existing xsd:schema element, and a new xsd:import element to be added as a child of that xsd:schema element.
Listing 4: Import declaration snippet for the database domain
<xsd:schema … xmlns:
This import declaration refers to the namespace of the database domain and the location of the database domain schema file. See Appendix A for a list of the available domains and their namespaces and schema files.
Add these three pieces of code (the unit declaration, the unit type definition, and the import declaration) to your XSD file, making sure that the attribute "type" of the unit declaration refers to the name of the complexType definition. In the complexType definition, make sure that the reference to the database domain in the tag "extension" uses the correct name of the type from which this type is derived. The complete XSD file looks like the code in Listing 5.
Listing 5. Complete XML schema file with custom unit
<?xml version="1.0" encoding="UTF-8" standalone="no"?> <xsd:schema … xmlns: > </xsd:schema>
Note: By convention, unit names have the prefix "unit" followed by a dot and an identifying string. In this case, the unit is named unit.MySQLSystemUnit.
Adding a capability to the domain
To complete the MySQL example, add a capability with three attributes (Version, Port and MaxAllowedPacket) to the XSD. The capability definition is used in the topology editor to represent the functionality that units can provide to other units.
Note: It is possible to add attributes to the unit type, but by convention, all custom attributes are placed on capabilities rather than on units.
The definition of a capability follows steps similar to the unit definition:
- Add a new XSD element with the attribute's name, substitutionGroup and type. The value of the attribute substitutionGroup must be set to "core:capability". By convention, the name of the capability starts with "capability."
- Add the type definition of the new XSD element as a complexType. In the type definition, specify the supertype of the capability and the attributes of the capability, if any.
- If attributes or capabilities are referenced from other domains, add the corresponding namespace and import declarations.
Listing 6 shows a snippet for a new SQL database system capability, including both the element declaration and type definition.
Listing 6: Capability snippet
>
Listing 7 shows all changes made to the mysql.xsd file when the capability "capability.MySQLDatabaseSystem" is added. The new capability extends the existing capability "DatabaseSystem" from the predefined database domain. In addition, the type of the attribute "Port" is taken from the domain operating system (os), which requires the additional namespace "os" and the XSD import declaration.
Add the changes to your mysql.xsd file and validate the contents by right-clicking the XSD file in the Project Explorer view and then selecting Validate. If the validation is successful, proceed with the next section of the tutorial. If the validation process shows errors, makes sure that your code matches the code in Listing 7. The complete XSD file is also provided for download in the Resources section.
Listing 7. Complete XSD file with a new unit and capability
<?xml version="1.0" encoding="UTF-8" standalone="no"?> <xsd:schema xmlns: <xsd:import <xsd:import <xsd:import <!-- Custom unit --> > <!-- Custom capability --> > </xsd:schema>
You may add as many unit and capability types to the XSD file as you wish to include in the domain. When you are done adding new topology elements, it's time to convert the XSD file into a domain extension that the topology editor can use.
Generate the domain extension
In this section, you generate an Ecore Model and an EMF Model (also called a genmodel) from the XML schema definition. From the genmodel, you can create the plug-in code for the domain extension.
- Right-click the mysql.xsd file in the Package Explorer view and choose New > Other so that the New Wizard" opens.
- In Rational Software Architect 7.5, select Eclipse Modeling Framework > EMF Model and then click Next. In Version 8.0, select Eclipse Modeling Framework > EMF Generator Model and then click Next.
- In the following dialog window, titled either "New EMF Model" (see Figure 6) or "New EMF Generator Model," select the ecore folder and make sure that the file name of the genmodel is set to mysql.genmodel.
- Then click Next.
Figure 6. Edit name and location for the genmodel
- Select the XML Schema model importer and click Next.
- The mysql.xsd file should automatically appear in the text field "Model URIs". If it is not, select Browse Workspace and select your mysql.xsd file.
- Click Load to start the import of the XSD file.
- If the XSD file contains no errors, the Next button is activated; click this button to continue.
- In the next dialog, select the root package and the packages that have to be imported: In the upper table of the dialog box, select the "org.example.mysql" package. In the lower box, check all referenced packages (see Figure 7).
Figure 7. Completed Package Selection
- Then click Finish. A mysql.ecore file and a mysql.genmodel file are created in the "ecore" folder of your project.
- Double-click the "mysql.genmodel" to open the file in the genmodel editor and select the top root node of the model.
- Edit the properties of the genmodel file and specify the following attributes, as shown in Figure 8:
- Set "Compliance Level" to "1.4"
- Set "Non-NLS Markers" to "true"
- Delete the ".edit" from the path entry "Edit Directory"; the new value for this field is "/org.example.mysql/src".
- Save the changes to the genmodel file (Ctrl+s).
Figure 8. Edit the genmodel properties
- In the genmodel editor, right click on the top node labeled "Mysql" and generate the Model Code (see Figure 9), the Edit Code (see Figure 10), and finally the Topology Edit Code (see Figure 11).
In the Project Explorer view you will see the generated artifacts of each generation step. The "Model Code" generation produces the EMF code for the domain artifacts and the domain validators. The "Edit Code" generator creates the plug-in infrastructure to edit the model that is the plug-in.xml, META-INF directory, and provider classes as the ItemProvider and the EditPlugin. These files allow you to create instances of the units and capabilities in topologies. You don't need to edit these files directly.
The domain generator creates a new folder named "templates", where the topology templates for the concrete and the conceptual MySQL unit are stored. Additionally, the generator creates a new project called "org.example.mysql.ui" which contains the plug-in code for the diagram extension.
Figure 9. Generate Model Code
Figure 10. Generate Edit Code
Figure 11. Generate Topology Code
Test the new technology domain in the runtime
To test the newly created technology domain, run the generated plug-in in a runtime instance of the workbench.
Open the "plugin.xml" file from "org.example.mysql" project and click Launch an Eclipse application as shown in Figure 12.
Figure 12. plugin.xml of the org.example.mysql project
The runtime instance of the workbench is initialized in a new window.
- Add a new project in the runtime instance (File > New > Project | General > Project) and name it "org.example.mysql.topology".
- In the Project Explorer, right click the newly created project and select New > Topology.
- In the dialog box, give the topology a name such as "MySQLExample" and click Finish.
- By default, palette entries from a generated domain are located in the Middleware palette drawer. Open this drawer, click the
MySQLDatabaseSystemUnitentry, and place it onto the topology diagram (see Figure 13).
Note: You could also use the quick palette to select the new unit. Click on the topology diagram and press Ctrl+t and a popup window with available units opens. You can now browse through the units or, more quickly, enter the first letters of the unit's name.
Figure 13. Select a MySQLDatabaseUnit from the palette
- After placing the unit on the diagram, check for the presence of the MySQLDatabaseSystem capability and its attributes in the Properties view of the unit.
Note:
You can also access capabilities and requirements directly by double-clicking the unit and going to the Capabilities page (see Figure 14).
Figure 14. MySQLDatabaseUnit and its capability
To review the created topology code with strong XML types, save the diagram (Ctrl+s) and open the topology file in a text editor (Right click MySQLExample.topology and then click Open With > Text Editor). The source of the topology file should look like Figure 15.
Figure 15. Source Code of the .topology file with strong xml types for the mysql extension
This source code shows that the MySQL units are distinct types and not merely copies of other units in the editor. Publishers and other extensions to the topology editor can now distinguish these units from other database units.
Close the runtime instance (Ctrl+F4) and proceed with the next section of this tutorial.
Configure the palette of the topology editor
The generation process creates topology templates, which are entries in the palette that contain one or more units for you to add to topologies. In this case, the generation process created two new templates for each new unit type that you defined, one containing a conceptual version of the unit and the other containing a concrete version of the unit. These templates are placed in the "Middleware" drawer of the palette by default.
The locations of the templates are specified in the plugin.xml files of the UI and domain project. In the UI project, drawers (top-level categories) and stacks (groups of related templates) are defined, which serve as containers for topology templates. Each drawer can contain individual template entries, as well as stacks of related templates. Each drawer, stack, and template must have a unique identifier on the same hierarchy level so that each path definition is unique. In the domain project, templates are provided with a UI binding which includes a palette path attribute that links the template to one or more drawers or stacks. If the path definition is invalid or missing, the template will not be shown in the palette.
In the MySQL example, a new drawer will be created that contains all elements of the example.org domain. Within that drawer, the existing MySQL stack (which has been created by the Domain Generation Toolkit) will be included.
- Open the plug-in editor of the UI project (double-click the plugin.xml) and go to the Extensions tab.
- Expand org.eclipse.gmf.runtime.diagram.ui.paletteProviders > com.ibm.ccl.soa.deploy.core.ui.providers.DefaultPaletteProvider > com.ibm.ccl.soa.deploy.core.ui.providers.DeployCorePaletteFactory. As shown in Figure 16, the Topology Domain Generator Toolkit has created a default palette entry for the MySQL database in a stack named mysqlStack in the path /serverSoftwareDrawer (representing the "middleware" drawer).
Figure 16. Generated Palette Entry for the MySQL Domain
- To extend the palette with a custom drawer, right click the contribution entry
com.ibm.ccl.soa.deploy.core.ui.providers.DeployCorePaletteFactoryand select New > entry as shown in Figure 17.
Figure 17. Add a new palette entry
On the right side of the screen, you can edit the details of the new extension entry.
- In the kind field, select drawer and enter the id "ExampleOrgExtensions". The drawer is placed as a top level element in the palette, which is indicated by a ‘/' in the path field.
- In the label field, specify "example.org Extensions" for the label of the new drawer. In the case that an attribute's value remains empty, a default value is set. Optionally, you can also set a description and icons for the new drawer.
- After you have entered the data, select the entry example.org Extensions and click on the Up button in the dialog (see Figure 18). Moving the drawer definition above the stack definition ensures that the new drawer is created before the mysqlStack is inserted.
Figure 18. Check that the new drawer is placed above the stack entry (left side) and the details of the new drawer (right side)
- The next step is to link the mysqlStack entry to the newly created drawer entry. To do this, open the Mysql Stack entry and set its path attribute to "/ExampleOrgExtensions".
- Save the UI plugin.xml (Ctrl+s).
Next, update the paths of the templates to point to the new drawer and stack.
- Open the plugin.xml file of the domain project (not the UI project) and go to the Extensions tab. Expand the extension point
com.ibm.ccl.soa.deploy.core.domains. Each template in the domain extension is defined as a resourceType (which contains general information about the resource) and a resourceTypeUIBinding (which includes the UI definition of the resource, including its location in the Palette and its labels and icons). In the resourceTypeUIBinding, the attribute "path" defines the palette path.
- For both templates, set the value of the path attribute to /ExampleOrgExtensions/mysqlStack/ as shown in Figure 19 and save the changes.
Figure 19. Extensions dialog of the plugin.xml file of the domain project with adapted value for the attribute "path"
- Test the new configuration in the runtime environment by clicking Launch an Eclipse application on the Overview tab. You can see the new drawer and stack in the Palette as in Figure 20.
Figure 20. The new Palette drawer
You can add as many new Palette drawers, stacks, and templates as you want. By default, each template contains only one unit, but you can create templates with as many units and capabilites as you want by creating a topology with those units and capabilities, saving that topology to the "templates" folder of the domain project, and creating resourceType and resourceTypeUIBinding elements as shown in the previous example.
You can also add Palette entries to the existing drawers; the IDs of these default drawers are listed in Appendix B.
Export and install the new domain extension plug-ins
To exchange the created plug-ins and templates easily, all plug-ins can be assembled into one update site project that may be accessed by all users of the extension. An update site consists of a collection of features and each feature itself consists of a collection of plug-ins which are installed together. For the MySQL example, the update site will provide one feature that includes the domain and UI plug-in.
Before creating the update site, make sure that the templates folder of the domain plug-in is included in the plug-in archive:
- Open the plugin.xml file of the domain plug-in in the plug-in editor and go to the Build tab.
- In the Binary Build section, make sure that the check box next to the "templates" folder is selected.
- Save the changes (Ctrl+s) and close the editor (Ctrl+F4).
Create a new feature to contain the domain and UI plug-ins:
- Create a new Feature Project (File > New | Plugin Development > Feature Project).
- In the dialog shown in Figure 21, enter a name for the project such as "org.example.mysql.feature" and a Feature Name such as "MySQL Feature" and then click Next.
- In the next dialog, select the plug-ins to include in the feature (see Figure 22). In this case, select the checkboxes of the two mysql plug-ins (org.example.mysql and org.example.mysql.ui) and click Finish.
The new project is created and the feature.xml editor opens in the workspace.
Figure 21. Create a new feature project
Figure 22. Selecting plug-ins
- In the editor, go to the Plug-ins tab and check that both plug-ins are added properly. By default, the version numbers of the plug-ins is set to "0.0.0", which is a placeholder that refers to the latest version configured in the plug-in project.
- On the Information tab, you can change the overall information of the feature (such as the feature description, the copyright, the license agreement and additional websites to visit). This information is displayed in the "Software Update" dialog ahead when someone installs the feature.
Next, create the update site to allow other people to install the domain extension:
- Return to the Overview tab and in the Publishing section, click Create an Update Site Project (see Figure 23).
Figure 23. Overview page of the feature.xml editor
- In the New Update Site dialog, enter a project name (e.g.
org.example.mysql.updatesite) and click Finish. The Update Site editor opens automatically to the Site Map tab, from which you can add new categories and features to include in the update site.
- Click New Category and enter "MySQL Extension" as value for the Name and Label fields.
- Then select the category "MySQL Extension" and click Add Feature. A selection dialog opens where you can add the mysql feature (org.example.mysql.feature).
- Click Build All to build the plug-ins, the feature, and the Update Site (see Figure 24).
- Finally, delete the generated files "content.xml" and "artifacts.xml" from the update site project to avoid an error message during the installation of the new plug-ins.
Figure 24. Complete configuration of the site.xml for the mysql example
Now you can share the update site with other people who might want to use the domain extension. The update site project contains all of the necessary plug-ins and features in the "features" and "plugins" folders, so you do not need to include the other projects when you distribute the update site. Follow these instructions to install the domain extension from the update site:
- Open the Software Installation Dialog (Help > Software Updates) and select the Available Software tab.
- Click Add Site and select the folder that contains your update site project. In the Software Update dialog, the new MySQL Extension with the MySQL Feature is displayed as shown in Figure 25.
- Select the feature's checkbox and click Install.
- Restart the workbench.
- To verify that the domain extension is installed, test the domain by creating a new project with a topology and adding the units in the domain to the topology.
Figure 25. Software Update Dialog with the MySQL Feature
Summary
This tutorial. For information on adding validators to custom domains, see the tutorial titled "Use the topology editor in Rational Software Architect to add a custom validator" (see Resources)
Downloads
Resources
Learn
- Learn more about custom domains and adding validators in this tutorial:
Use the topology editor in Rational Software Architect to add a custom validator.
- Learn more about the deployment architecture tools and the topology editor: Tutorial: Planning deployment with the topology editor
- Tutorial: Create a deployment topology diagram in IBM Rational Software Architect
- Basic Concepts behind the Topology Editor: Anatomy of a topology model in Rational Software Architect Version 7.5 Part 1 and Part 2
- Learn more about IBM Rational Software Architect: developerWorks page for Rational Software Architect
- Check the Rational Software Architect Information Center for documentation
- Find technical details in the IBM Rational Document Download Information Center and IBM Rational Documentation a free, fully enabled. trial version of Rational Software Architect
- Download trial versions of other IBM Rational software.
- Download these IBM product evaluation versions and get your hands on application development tools and middleware products from IBM® DB2®, IBM® Lotus®, IBM® Tivoli®, and IBM® WebSphere®.
Discuss
- Participate in the Enterprise Architecture and Business Architecture forum, which is dedicated to the collaboration of the Enterprise Architecture community, where you can share information about methods, frameworks, and tool implementations. Discussions include tool-specific technical exchanges about Rational Software Architect.
- Join the Development Tools forum to ask questions and share your experiences with colleagues.
- Check out other developerWorks blogs and get involved in the developerWorks. | http://www.ibm.com/developerworks/rational/library/10/extendingthetopologyeditorwithcustomtechnologydomains/index.html?ca=drs- | CC-MAIN-2013-48 | refinedweb | 4,910 | 53.81 |
I found that the read.nexus function in ape does not read node annotations written within square brackets.(If you don’t know “ape”, it is a common R package for phylogenetic analysis.) Commonly-used programs like Figtree or TreeAnnotator outputs this bracket-style annotations in Nexus but can not output annotations in simple Newick format, which can be read by the read.tree function.
A couple of google searches told me that some packages like “PHYLOCH” can read bracket-style annotations in Nexus format. However, the installation of PHYLOC got stuck with a dependency error.
This became a major obstacle on my analysis. So, I decided to write a code to convert the bracket style annotations to the simple newick ones, that is, a code converting a text like below,
((a:1, b:1)[&posterior=1.0]:1, (c:1,d:1)[&posterior=0.98]:1)[&posterior=0.99]:1;
into,
((a:1, b:1)1.0:1, (c:1,d:1)0.98:1)0.99:1;
The outputs of Figtree/TreeAnnotator usually contains annotations other than posterior probability, such as node height. So, if I can choose an annotation key instead of only targeting “posterior”, the code would be more useful.
This is a good (or maybe a painful) practical for regular expressions. Initially, I tried to write the code in shell script using Linux’s grep and sed things, but soon found Python is an easier solution.
First thing to do is finding texts within square brackets and “&”, for example, “[&posterior=1.0]”. A bit tricky point is the text within brackets must not include brackets. Otherwise, a long text like “[&posterior=1.0]:1, (c:1,d:1)[&posterior=0.98]” will be matched.
After a bit of Google searches, I found this is done by, “\[&(.*?)\]”. “.*?” is a non-greedy form of matches to any letters with any length, which does not extend when “]” is found. In Python, this is written like below.
re.findall("\[&(.*?)\]", line)
Once texts within brackets are extracted, they will be parsed.
The second tricky point is the annotation texts are “comma-separated” (each entry is separated by a comma), but commas within curly braces must be ignored when splitting entries. Otherwise, an annotation like “[&height_95={0.1,0.3},posterior=0.98]” will be split into 3 elements, “height_95={0.1”, “0.3}” and “posterior=0.98”.
I could not find a good solution to this even after hours of googling, and I resorted to replacing the commas within braces with “-“.
re.sub("{([0-9]+.[0-9E-]+),([0-9]+.[0-9E-]+)}", "\\1-\\2", text)
re.sub substitutes the text match with the first argument with the second argument. “{([0-9]+.[0-9E-]+),([0-9]+.[0-9E-]+)}” matches with two numbers surrounded by braces and separated by a comma, The “( )” captures the matched numbers, and the captured values are referenced by “\1” and “\2” when substitution occurs.
Annotations are then split by commas and stored in a Python dictionary. They are called with a specific key to replace the original bracket annotations.
The following code is the final version.
import sys import re def node_attributes(txt): txt = re.sub("{([0-9]+.[0-9E-]+),([0-9]+.[0-9E-]+)}", "\\1-\\2", txt) attrs = txt.lstrip("&").split(",") attr_val = {} for attr in attrs: attr = attr.split("=") attr_val[attr[0]] = attr[1] return attr_val if len(sys.argv) > 2: key = sys.argv[2] else: key = "posterior" with open(sys.argv[1], "r") as f: for line in f: s = re.findall("\[&(.*?)\]", line) if s: for i, m in enumerate(s): #print i, m attr = node_attributes(m) if key in attr: line = re.sub(m, attr[key], line) else: line = re.sub(m, "", line) line=re.sub("\[&", "", line) line=re.sub("\]", "", line) print line.rstrip("\n")
This code runs on a text file containing trees with bracket annotations. If you replace “posterior” in the second argument with “height”, it extracts node heights if annotations include them.
python replace_annotation.py tree.txt posterior | https://tmfujis.wordpress.com/2014/08/30/code-to-extract-node-annotations-from-nexus/ | CC-MAIN-2022-33 | refinedweb | 665 | 59.5 |
If I am not using AFR, and I've decided to no longer use a server brick.I will loose those files that are in that server brick. With the new namespace
architecture, what is the proper way to remove the brick from service and migrate the files to other existing bricks?If I remove the brick from the client config, the files are still listed in the namespace brick, but are no longer accessible. I assume I'll have some problems if I just copy over from the old brick back into the client since those file suposedly exist according
to the namespace brick. -- or is that the right thing to do? _________________________________________________________________Need a brain boost? Recharge with a stimulating game. Play now! | http://lists.gnu.org/archive/html/gluster-devel/2007-07/msg00507.html | CC-MAIN-2014-42 | refinedweb | 124 | 81.63 |
Ik neem aan dat je een opgave hebt gekregen?
Stuur deze even naar ErikPeeters90atgmaildotcom
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Ik neem aan dat je een opgave hebt gekregen?
Stuur deze even naar ErikPeeters90atgmaildotcom
ok so i got some help from someone.
i know have this question: can i get rid of the visual part? because i don't need that just now
i only need it in console atm
Code java:
class Car { private int xPos; private int yPos; private int width; private int height; Color color; Car(int x, int y, int w, int h, Color color) { this.xPos = x; this.yPos = y; this.width = w; this.height = h; this.color = color; } boolean contains(Point p) { return new Rectangle(xPos, yPos, width, height).contains(p); } public void paintCar(Graphics g) { g.setColor(color); g.fillRect(xPos,yPos,width,height); g.setColor(Color.BLACK); g.drawRect(xPos,yPos,width,height); } } public class RhTest extends JPanel { // Very easy to add othe cars to the board, just specify position, size and colour // Double array to enter x position, y position, width and height int[][] dims = { // x y w h { 50, 100, 100, 50 }, { 0, 0, 100, 50 }, { 250, 0, 50, 150 }, { 150, 50, 50, 150 }, { 0, 50, 50, 150 }, { 0, 200, 50, 100 }, { 200, 200, 100, 50 }, { 100, 250, 150, 50 } }; // Colours of the cars are entered here Color[] colors = { Color.red, Color.green, Color.yellow, Color.blue, Color.pink, Color.orange, Color.cyan, Color.black }; Car[] cars; int selectedIndex; boolean drag = false; // added here boolean mouseInside, collide; // end of add final int OFFSET = 1; public RhTest() { initCars(); setBorder(BorderFactory.createLineBorder(Color.black)); addMouseListener(new MouseAdapter(){ public void mousePressed(MouseEvent e){ Point p = e.getPoint(); // Check to see if user has clicked on a car for(int j = 0; j < cars.length; j++) { if(cars[j].contains(p)) { selectedIndex = j; drag = true; break; } } } public void mouseReleased(MouseEvent e) { drag = false; } }); addMouseMotionListener(new MouseMotionAdapter(){ public void mouseDragged(MouseEvent e){ if(drag) { moveCar(e.getX(),e.getY()); } } }); } private void moveCar(int x, int y){ final int CURR_X = cars[selectedIndex].getX(); final int CURR_Y = cars[selectedIndex].getY(); final int CURR_W = cars[selectedIndex].getWidth(); final int CURR_H = cars[selectedIndex].getHeight(); final int OFFSET = 1; if ((CURR_X!=x) || (CURR_Y!=y)) { // The car is moving, repaint background // over the old car location. repaint(CURR_X,CURR_Y,CURR_W+OFFSET,CURR_H+OFFSET); // Update coordinates. if (CURR_W > CURR_H) { cars[selectedIndex].setX(x); } if (CURR_H > CURR_W) { cars[selectedIndex].setY(y); } // Repaint the car at the new location. repaint(cars[selectedIndex].getX(), cars[selectedIndex].getY(), cars[selectedIndex].getWidth()+OFFSET, cars[selectedIndex].getHeight()+OFFSET); } } private void initCars() { cars = new Car[colors.length]; for(int j = 0; j < cars.length; j++) { int x = dims[j][0]; int y = dims[j][1]; int w = dims[j][2]; int h = dims[j][3]; cars[j] = new Car(x, y, w, h, colors[j]); } } public Dimension getPreferredSize() { return new Dimension(300,300); } public void paintComponent(Graphics g) { super.paintComponent(g); for(int j = 0; j < cars.length; j++) cars[j].paintCar(g); // added here if(collide) g.drawString("Collision!", 10, 20); //end of add } } public class Main { public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); } }); } private static void createAndShowGUI() { JFrame f = new JFrame("The Rush Hour Game"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.add(new RhTest()); f.setSize(317,337); f.setVisible(true); } }
Are you asking how to move the logic from the paintComponent() method to use a println()?
Sometimes it is easier to start from the beginning than to try to rewrite code that is written for a completely different environment.
yes i think that is what i need.
you are probably right but i just don't have enough time to start from the begining again
It could take longer to rewrite a GUI app to run in a console. Your choice of course.
i dont know how to start working on both so idk :/
Why both?
i mean i dont know how to take out the GUI and i also don't know how i should start all over
--- Update ---
How can i change the values of an array and stock it in another?
Use an assignment statement:Use an assignment statement:Quote:
change the values of an array
Code :
theArray[theIndex] = value; // change array's contents at index element
Can you explain what that means?Can you explain what that means?Quote:
stock it in another
i mean that after you change the values, the program should print the new array and you should be able to keep doing this. like you are moving the cars 1 block at a time and take a picture after every move
The Arrays class's deepToString() method is useful for printing out the contents of a 2 dim array for debugging:The Arrays class's deepToString() method is useful for printing out the contents of a 2 dim array for debugging:Quote:
the program should print the new array
Code :
System.out.println("an ID "+ java.util.Arrays.deepToString(theArrayName));
If the print out is for a user to see, you'll have to write some loops and use print()
i'm almost finished now, but when i try to get an extern file (the level) i get this error:
--Error: File Not Found--
The data file could not be found. Check thefile name and try again.
where should the file be?
Where the program is looking for it to be.Where the program is looking for it to be.Quote:
where should the file be
To see where the program is looking for the file, Create a File object with the same path to the file that is currently being used and print out the value of the File class's get absolute path method.
if this is my game board
and each number represents a car
88= the border of the board
10= an open space
What should i write to make the numbers(cars) move and fill the other space with '10'??
Code java:
{int[][] board = { {8,88,88,88,88,88,88,8}, {8,22,22,22,37,23,36,8}, {8,33,34,34,37,23,36,8}, {8,33,10,45,45,23,10,11}, {8,30,30,36,10,10,10,8}, {8,10,39,36,10,31,31,8}, {8,10,39,35,35,32,32,8}, {8,88,88,88,88,88,88,8} };
Define the rules for moving a car. If a car is at 3,4 what other locations are legal moves? There are 8 locations immediately adjacent.Define the rules for moving a car. If a car is at 3,4 what other locations are legal moves? There are 8 locations immediately adjacent.Quote:
make the numbers(cars) move
What if the other location is not empty (has a value other than 10)?
Not sure where the "other space" is?Not sure where the "other space" is?Quote:
fill the other space with '10'??
i mean the space that becomes empty if a car is moved
If you know where the car was located before it was moved, that would be the place that is empty after the car was moved.
i know but as i said, i have no idea how to write this. i started lessons only 1 month ago
Write what? Describe in simple steps what you are trying to write.
-ask the player which car he wants to move
-ask the player in which direction
-show the gameboard where the car is moved --> so let the number move and fill the open space with 10
Which step is the problem?
Take the first step: What problems do you have?
the problem is that i don't know how to move the number in the array when the player calls it.
the program asks the number and the direction but then it doesnt do anything else
That wasn't the step to work on. I don't see that step in the list of steps in post #44.That wasn't the step to work on. I don't see that step in the list of steps in post #44.Quote:
how to move the number in the array when the player calls it.
Are you adding new steps to that list? If so, please post the new list of steps.
You need to work on one step at a time. The first step was:
-ask the player which car he wants to move
How will the program do that? | http://www.javaprogrammingforums.com/%20whats-wrong-my-code/22618-rush-hour-game-2-printingthethread.html | CC-MAIN-2016-18 | refinedweb | 1,419 | 65.01 |
#include <CGAL/Regular_triangulation_3.h>
CGAL::Triangulation_3< Traits, TDS, SLDS >.
Let \( {S}^{(w)}\) be a set of weighted points in \( \mathbb{R}^3\). \) (see Figure 45.2).
Four.
If
TDS::Concurrency_tag is
Parallel_tag, some operations, such as insertion/removal of a range of points, are performed in parallel. See the documentation of the operations for more details.
CGAL::Triangulation_3
CGAL::Delaunay_triangulation_3
Creates an empty regular triangulation, possibly specifying a traits class
traits.
lock_ds is an optional pointer to the lock data structure for parallel operations. It must be provided if concurrency is enabled.
Copy constructor.
The pointer to the lock data structure is not copied. Thus, the copy won't be concurrency-safe as long as the user has not called
Triangulation_3::set_lock_data_structure.
Equivalent to constructing an empty triangulation with the optional traits class argument and calling
insert(first,last).
If parallelism is enabled, the points will be inserted in parallel.
Returns the weighted circumcenter of the four vertices of c.
rt.
dimension()\( =3\) and
cis not infinite.
Returns the dual of facet
f, which is.
in dimension 3: either a segment, if the two cells incident to
f are finite, or a ray, if one of them is infinite;
in dimension 2: a point.
rt.
dimension()\( \geq2\) and
fis not infinite.
Compute the conflicts with
p.
cmust be in conflict with
p.
rt.
dimension()\( \geq2\), and
cis in conflict with
p.
Triplecomposed of the resulting output iterators.
Inserts the weighted point
p in the triangulation.
The optional argument
start is used as a starting place for the search.
If this insertion creates a vertex, this vertex is returned.
If
p coincides with an existing vertex and has a greater weight, then the existing weighted point becomes hidden (see
RegularTriangulationCellBase_3).
The optional argument
could_lock_zone is used by the concurrency-safe version of the triangulation. If the pointer is not null, the insertion will try to lock all the cells of the conflict zone, i.e. all the vertices that are inside or on the boundary of the conflict zone. If it succeeds,
*could_lock_zone is true, otherwise it is false (and the point is not inserted). In any case, the locked cells are not unlocked by the function, leaving this choice to the user.
Inserts the weighted point
p in the triangulation and returns the corresponding vertex.
Similar to the above
insert() function, but takes as additional parameter the return values of a previous location query. See description of
Triangulation_3::locate().
Inserts the weighted points in the range
[first,last).
It returns the difference of the number of vertices between after and before the insertions (it may be negative due to hidden points). Note that this function is not guaranteed to insert the points following the order of
InputIterator, as
spatial_sort() is used to improve efficiency. If parallelism is enabled, the points will be inserted in parallel.
Inserts the weighted points in the iterator range
[first,last).
It returns the difference of the number of vertices between after and before the insertions (it may be negative due to hidden points). Note that this function is not guaranteed to insert the weighted points following the order of
WeightedPointWithInfoInputIterator, as
spatial_sort() is used to improve efficiency. If parallelism is enabled, the points will be inserted in parallel. Given a pair
(p,i), the vertex
v storing
p also stores
i, that is
v.point() == p and
v.info() == i. If several pairs have the same point, only one vertex is created, one of the objects of type
Vertex::Info will be stored in the vertex.
Vertexmust be model of the concept
TriangulationVertexBaseWithInfo_3..
If the hole contains interior vertices, each of them is hidden by the insertion of
p and is stored in the new cell which contains it.
rt.
dimension()\( \geq2\), the set of cells (resp. facets in dimension 2) is connected, not empty, its boundary is connected, and
plies inside the hole, which is star-shaped wrt
p.
This is a function for debugging purpose.
Checks the combinatorial validity of the triangulation and the validity of its geometric embedding (see Section Representation). Also checks that all the power spheres (resp. power circles in dimension 2, power segments in dimension 1) of cells (resp. facets in dimension 2, edges in dimension 1) are regular. When
verbose is set to true, messages describing the first invalidity encountered are printed. This method is mainly a debugging help for the users of advanced features.
Returns the vertex of the triangulation which is nearest to \( p\) with respect to the power distance.
This means that the power of the query point
p with respect to the weighted point in the returned vertex is smaller than the power of
p with respect to the weighted point for any other vertex. Ties are broken arbitrarily. The default constructed handle is returned if the triangulation is empty. The optional argument
c is a hint specifying where to start the search.
cis a cell of
rt.
Removes the vertex
v from the triangulation.
This function is concurrency-safe if the triangulation is concurrency-safe. It will first try to lock all the cells adjacent to
v. If it succeeds,
*could_lock_zone is true, otherwise it is false (and the point is not removed). In any case, the locked cells are not unlocked by the function, leaving this choice to the user.
This function will try to remove
v only if the removal does not decrease the dimension. The return value is only meaningful if
*could_lock_zone is true:
vis a finite vertex of the triangulation.
dt.
dimension()\( =3\).
Removes the vertices specified by the iterator range
[first, beyond).
The number of vertices removed is returned. If parallelism is enabled, the points will be removed in parallel. Note that if at some step, the triangulation dimension becomes lower than 3, the removal of the remaining points will go on sequentially.
Returns the position of the point
p with respect to the power circle of
f.
More precisely, it returns:
ON_BOUNDARY if
p is orthogonal to the power circle in the plane of the facet,
ON_UNBOUNDED_SIDE when their angle is less than \( \pi/2\),
ON_BOUNDED_SIDE when it is greater than \( \pi/2\) (see Figure Triangulation3figsidedim2).
f.first, and does the same as in dimension 2 in this plane.
ON_BOUNDARY if
p is orthogonal to the circle,
ON_UNBOUNDED_SIDE when the angle between
p and the power circle of
f is less than \( \pi/2\),
ON_BOUNDED_SIDE when it is greater than \( \pi/2\).
ON_BOUNDED_SIDE for a point in the open half plane defined by
f and not containing any other point of the triangulation,
ON_UNBOUNDED_SIDE in the other open half plane.
If the point
p is collinear with the finite edge
e of
f, it returns:
ON_BOUNDED_SIDE if \( \Pi({p}^{(w)}-{z(e)}^{(w)})<0\), where \( {z(e)}^{(w)}\) is the power segment of
e in the line supporting
e,
ON_BOUNDARY if \( \Pi({p}^{(w)}-{z(e)}^{(w)})=0\),
ON_UNBOUNDED_SIDE if \( \Pi({p}^{(w)}-{z(e)}^{(w)})>0\) .
rt.
dimension()\( \geq2\).
In dimension 1, returns.
ON_BOUNDED_SIDE if \( \Pi({p}^{(w)}-{z(c)}^{(w)})<0\), where \( {z(c)}^{(w)}\) is the power segment of the edge represented by
c,
ON_BOUNDARY if \( \Pi({p}^{(w)}-{z(c)}^{(w)})=0\),
ON_UNBOUNDED_SIDE if \( \Pi({p}^{(w)}-{z(c)}^{(w)})>0\) .
rt.
dimension()\( = 1\).
Returns the position of the weighted point \( p\) with respect to the power sphere of
c.
More precisely, it returns:
ON_BOUNDED_SIDEif \( \Pi({p}^{(w)}-{z(c)}^{(w)})<0\) where \( {z(c)}^{(w)}\) is the power sphere of
c. For an infinite cell this means either that
plies strictly in the half space limited by its finite facet and not containing any other point of the triangulation, or that the angle between
pand the power circle of the finite facet of
cis greater than \( \pi/2\).
ON_BOUNDARYif p is orthogonal to the power sphere of
ci.e. \( \Pi({p}^{(w)}-{z(c)}^{(w)})=0\). For an infinite cell this means that
pis orthogonal to the power circle of its finite facet.
ON_UNBOUNDED_SIDEif \( \Pi({p}^{(w)}-{z(c)}^{(w)})>0\) i.e. the angle between the weighted point
pand the power sphere of
cis less than \( \pi/2\) or if these two spheres do not intersect. For an infinite cell this means that
pdoes not satisfy either of the two previous conditions.
rt.
dimension()\( =3\).
vertices_on_conflict_zone_boundarysince CGAL-3.8.
Similar to
find_conflicts(), but reports the vertices which are in the interior of the conflict zone of
p, in the output iterator
res.
The vertices that are on the boundary of the conflict zone are not reported. Returns the resulting output iterator.
rt.
dimension()\( \geq2\), and
cis a cell containing
p.
Similar to
find_conflicts(), but reports the vertices which are on the boundary of the conflict zone of
p, in the output iterator
res.
Returns the resulting output iterator.
rt.
dimension()\( \geq2\), and
cis a cell containing
p. | https://doc.cgal.org/latest/Triangulation_3/classCGAL_1_1Regular__triangulation__3.html | CC-MAIN-2022-05 | refinedweb | 1,476 | 56.76 |
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Game Scripting with Python – Tim Glasser
1
Game Scripting with Python – Tim Glasser
Contents
Week 1 Lecture: Intro to Python and IDLE Lab: Start Overview assignments Homework: Finish Overview assignments. Week 2: Lecture: Syntax Lab: Syntax assignments Homework: Complete Syntax assignments Week 3: Lecture: Control Flow Lab: Control Flow assignments Homework: Complete Control Flow assignments Week 4: Lecture: Functions Lab: Functions assignments Homework: Complete Functions assignments Week 5: Lecture: Numbers and Strings in Detail Lab: Numbers and Strings in Detail assignments Homework: Complete Numbers and Strings in Detail assignments Week 6: Lecture: Lists, Dictionaries and Tuples Lab: Lists, Dictionaries and Tuples assignments Homework: Complete Lists, Dictionaries and Tuples assignments Week 7: Lecture: Object Oriented Programming Lab: Start end term project with PyGame Homework: End term project with PyGame
2
Game Scripting with Python – Tim Glasser Week 8: Lecture: Input and Output Lab: Input and Output assignments Homework: Complete Input and Output assignments Week 9: Lecture: Modules Lab: Modules assignments Homework: Complete Modules assignments Week 10: Lecture: Handling Errors Lab: Handling Errors assignments Homework: Complete Handling Errors assignments Week 11: Lecture: Summary of the Course Lab: Show and tell end-term project Homework: Appendix A Tic Tac Toe Appendix B PyGame Appendix C Object Oriented Programming with Pygame
3
Game Scripting with Python – Tim Glasser
Week 1 - Introduction
Why Python? Python is a dynamic object-oriented programming language that runs on Windows, Linux/Unix, Mac OS X, Palm Handhelds, and Nokia mobile phones. Python has also been ported to the Java and .NET virtual machines. It is distributed under an OSIapproved open source license that makes it free for programmers to use, even for commercial products. • • • • Open Source/Free Manages Complexity Object Oriented Powerful Expandability Packages Industry Darling MotionBuilder Maya Major Studios
A Simple Example Let’s write a simple Python program in a script. All python files will have extension .py. So put the following source code in a test.py file. #!/usr/bin/python print "Hello, Python!" This will produce following result: Hello, Python! You have seen a simple Python program in interactive as well as script mode, now lets see few basic concepts related to Python Syntax:
4
Game Scripting with Python – Tim Glasser
Another Example Here is another slightly more complex example. Suppose I wish to find the value of:
g ( x) =
x 1 − x2
for x = 0.0, 0.1, ..., 0.9. I could find these numbers by placing the following code in a file, say fme.py, and then running the program by typing python fme.py at the command-line prompt. for i in range(10): x = 0.1*i print x print x/(1-x*x)
This will produce following output: 0.0 0.0 0.1 0.10101010101 0.2 0.208333333333 0.3 0.32967032967 0.4 0.47619047619 0.5 0.666666666667 0.6 0.9375 0.7 1.37254901961 0.8 2.22222222222 0.9
5
Game Scripting with Python – Tim Glasser 4.73684210526 How does the program work? First, Python’s range() function is an example of the use of lists. Lists are absolutely fundamental to Python. Resist the temptation to treat it as the English word “list,” instead always think about the Python construct list. Python’s range() function returns a list of consecutive integers, in this case the list [0,1,2,3,4,5,6,7,8,9]. As you can guess, this will result in 10 iterations of the loop, with i first being 0, then 1, etc. The code:
for i in [2,3,6]: Would give us three iterations, with i taking on the values 2, 3 and 6. A More Complex Example This code reads a text file, specified on the command line, and prints out the number of lines and words in the file:
# reads in the text file whose name is specified on the # command line, and reports the number of lines and words import sys def checkline(): global l global wordcount w = l.split() wordcount += len(w) wordcount = 0 f = open(sys.argv[1]) flines = f.readlines() linecount = len(flines) for l in flines: checkline() print linecount, wordcount
Say for example the program is in the file tme.py, and we have a text file test.txt with contents:
6
’This is an’. Each line is a string. Since sys is not loaded automatically. For floating-point. let’s explain sys.Game Scripting with Python – Tim Glasser This is an example of a text file.argv[1] will be the string ’x’ (strings in Python are generally specified with single quote marks). one of whose member variables is argv. the first and last of which are blank) If we run this program on this file. The readlines() function of the file class returns a list (keep in mind. the result is: python tme.argv[1]) created an object of file class ( Python is an Object Oriented Language). the value returned by calling readlines() is the five-element list [’’.argv. those command-line arguments are of course strings. say. “list” is an official Python term) consisting of the lines in the file. in which we run our program on the file x. we’d use int(). The latter is a Python list.py x 5 8 There are some features in this program which were not in the first example: • • • • • • use of command-line arguments file-manipulation mechanisms more on lists function definition library importation introduction to scope Introduction to Command-Line Arguments First.’example of a’. sys.’text file’. (There are five lines in all. If those strings are supposed to represent numbers. there is an end-of-line character in each string. Since the file here consisted of five lines. an integer argument. in Python. in Python we’d use float() Introduction to File Manipulation The line: f = open(sys. If we had. in this case tme.’’] (Though not visible here. we could convert them. Python includes a module named sys. and that string is one element of the list. element 0 of the list is the script name.py. we needed the import line.) 7 . In our example here. and assigned it to f . In Python.
So. For example: 2 + ’1.py above.’is’.’an’]. It splits a string into a list of words. a variable x might be bound to an integer at one point in your program and then be rebound to a class instance at another point. in checkline() when l is ’This is an’ then the list w will be equal to [’This’. sequences (lists or tuples) and dictionaries Strings v Numerical Values Python does distinguish between numbers and their string representations. Python would assume that l and wordcount are local to checkline() if we don’t inform it otherwise. the Python interpreter does internally keep track of the type of all objects. Python uses dynamic typing. the variable flines does not exist until the statement: flines = f. []. We do the latter with the global keyword.) Types of Variables/Values As is typical in scripting languages.readlines() is executed.). in this case. In other words. w will be equal to the empty list. In other words. in the program tme. for instance. etc. tested for in an if statement. A variable is created when the first assignment to it is executed. Thus Python variables don’t have types. but their values do. However.Game Scripting with Python – Tim Glasser Declaration. The method ( a method is a function contained in a class) split() is a member of the string class. Python’s types include notions of scalars. Local v Global If a function includes any code which assigns to a variable. Scope and Functions Variables are not declared in Python. Built-In Functions The function len() returns the number of elements in a list. the number of lines in the file (since readlines() returned a list in which each element consisted of one line of the file). which is blank. in the code for checkline(). So. The functions eval()and str() can be used to convert back and forth.5’ 8 . type in the sense of C/C++ int or float is not declared in Python. Also a variable which has not been assigned a value yet has the value None (and this can be assigned to a variable. For example. (In the case of the first line. then that variable is assumed to be local.
we check whether name is main .5’) 3. all of the following (some to be explained below) apply to any sequence type: • • • • • The default is to use blank characters as the splitting criterion. let’s add print __name__ to the code in fme.5’ There are also int() to convert from strings to integers.g. If the answer is yes. the commonalities. So. otherwise it was imported. For example. and the module currently being run is referred to as the variable __name__. to test whether a given module is running on its own.28’) 5. which are all array-like but with some differences. The top-level program is known to the interpreter as ‘__main__‘ . i. or via import. but other characters or strings can be used.py then the code in fme.Game Scripting with Python – Tim Glasser causes an error.e. you are in the top level. x[i]) The built-in len()function to give the number of elements in the sequence Slicing operations. as follows.py: 9 . versus having been imported by other code. but 2 + eval(’1. the extraction of subsequences The use of + and * operators for concatenation and replication The Use of name In some cases. and float(). This can be determined through Python’s built-in variable name .py is the top-level program. you type python fme.5’)) ’3. If.5 and str(2 + eval(’1. and your code was not imported. The use of brackets to denote individual elements (e. Whatever the Python interpreter is running is called the top-level program. it is important to know whether a module is being executed on its own.2800000000000002 Sequences Lists are actually special cases of sequences. for instance. to convert from strings to floating-point values: n = int(’32’) 32 x = float(’5. Note though.
.py: 10 .3 0.1 0.3 0. but printed out fme the second time. So.py __main__ 0.2 0.. [remainder of output not shown] Our module’s statement print __name__ printed out main the first time. when we run it on its own as python fme. [remainder of output not shown] Now look what happens if we run it from within Python’s interactive interpreter: >>> __name__ ’__main__’ >>> import fme Fme 0.Game Scripting with Python – Tim Glasser print __name__ for i in range(10): x = 0. First.208333333333 0.0 0...10101010101 0.1*i print x print x/(1-x*x) Let’s run the program twice.32967032967 .1 0.0 0.208333333333 0.0 0. let’s change our example above to fme2.2 0.32967032967 .10101010101 0.0 0.
Instead. this will be a vital point in using debugging tools.main() must be called. the code won’t be executed right away.10101010101 0.1*i print x print x/(1-x*x) if __name__ == ’__main__’: main() The advantage of this is that when we import this module. Here is an example of the latter: >>> import fme2 >>> fme2. 11 .1 0.47619047619 . stores the names in variables called name1 and name2.2 0.0 0.fme2. Among other things.208333333333 0. So get in the habit of always setting up access to main() in this manner in your programs.1) What is the difference between using "+" and ". says hello to both of them.32967032967 0.4 0." in a print statement? Try it! 1. Exercises: 1.2) Write a program that asks two people for their names.0 0.3 0.Game Scripting with Python – Tim Glasser def main(): for i in range(10): x = 0. either by the importing module or by the interactive Python interpreter...main() 0.
The script adds 3 to that number. then display the user’s random hand.4) Write a script that defines a card ( name value and suit). until the user enters quit 1. Then multiplies the result by 2. 1. subtracts 4. then prints the result. 1.6) Write a python script that prints the following figure \ | / @ @ * \"""/ 12 . subtracts twice the original number.3) Write a script that asks a user for a number.Game Scripting with Python – Tim Glasser 1. adds 3. then print it back again. It should ask the user how many cards they want.5) Create a Python script that uses a while loop to read in a line of text that the user enters.
These reserved words may not be used as constant or variable or any other identifier names. And Assert Break Class Continue Def exec finally for from global if 13 not or pass print raise return . or other object. Keywords contain lowercase letters only. and % within identifiers. Reserved Words: The following list shows the reserved words in Python. class. and digits (0 to 9). the identifier is a language-defined special name. $. If the identifier also ends with two trailing underscores. Python is a case sensitive programming language. Python Identifiers: A Python identifier is a name used to identify a variable. Starting an identifier with two leading underscores indicates a strongly private identifier. module.Game Scripting with Python – Tim Glasser Week 2 – Syntax Overview Invoking the interpreter with a script parameter begins execution of the script and continues until the script is finished. Python does not allow punctuation characters such as @. Starting an identifier with a single leading underscore indicates by convention that the identifier is meant to be private. the interpreter is no longer active. Here are following identifier naming convention for Python: Class names start with an uppercase letter and all other identifiers with a lowercase letter. Thus Manpower and manpower are two different identifiers in Python. underscores. When the script is finished. function. An identifier starts with a letter A to Z or a to z or an underscore (_) followed by zero or more letters.
The number of spaces in the indentation is variable. Blocks of code are denoted by line indentation. which is rigidly enforced. Following is the example having various statement blocks: Note: Don't try to understand logic or different functions used. but all statements within the block must be indented the same amount. in Python all the continuous lines indented with similar number of spaces would form a block. Both blocks in this example are fine: if True: print "True" else: print "False" However. "w") except IOError: import in is lambda try while with yield 14 . Just make sure you understand the various blocks even if they are without braces. the second block in this example will generate an error: if True: print "Answer" print "True" else: print "Answer" print "False" Thus.Game Scripting with Python – Tim Glasser Del Elif Else Except Lines and Indentation: One of the first caveats programmers encounter when learning Python is the fact that there are no braces to indicate blocks of code for class and function definitions or flow control. #!/usr/bin/python import sys try: # open file stream file = open(file_name.
close() file_name = raw_input("Enter filename: ") if len(file_name) == 0: print "Next time please enter something" sys.exit() try: file = open(file_name. 'Friday'] 15 . or () brackets do not need to use the line continuation character.exit() file_text = file. allow the use of the line continuation character (\) to denote that the line should continue. 'Tuesday'. For example: total = item_one + \ item_two + \ item_three Statements contained within the []. file_finish. "r") except IOError: print "There was an error reading file" sys. print "' When finished" while file_text != file_finish: file_text = raw_input("Enter text: ") if file_text == file_finish: # close the file file. {}. Python does.write("\n") file. 'Thursday'. 'Wednesday'.write(file_text) file. file_name sys.close break file.read() file. however. For example: days = ['Monday'.Game Scripting with Python – Tim Glasser print "There was an error writing to".close() print file_text Multi-Line Statements: Statements in Python typically end with a new line.exit() print "Enter '".
# This is a comment.Game Scripting with Python – Tim Glasser Quotation in Python: Python accepts single ('). Python! A comment may be on the same line after a statement or expression: name = "Madisetti" # This is again comment You can comment multiple lines as follows: # This is a comment. double (") and triple (''' or """) quotes to denote string literals. too. as long as the same type of quote starts and ends the string. all the following are legal: word = 'word' sentence = "This is a sentence. All characters after the # and up to the physical line end are part of the comment. The triple quotes can be used to span the string across multiple lines. # second comment This will produce following result: Hello. # I said that already. Python!".""" Comments in Python: A hash sign (#) that is not inside a string literal begins a comment. #!/usr/bin/python # First comment print "Hello. # This is a comment. Using Blank Lines: 16 . and the Python interpreter ignores them. too." paragraph = """This is a paragraph. For example. It is made up of multiple lines and sentences.
while.") Here "\n\n" are being used to create two new lines before displaying the actual line. and Python totally ignores it. sys.write(x + '\n') Multiple Statement Groups as Suites: Groups of individual statements making up a single code block are called suites in Python. such as if. Example: if expression : suite elif expression : suite else : 17 . x = 'foo'.stdout. you must enter an empty physical line to terminate a multi-line statement. This is a nice trick to keep a console window open until the user is done with an application. are those which require a header line and a suite. is known as a blank line.Game Scripting with Python – Tim Glasser A line containing only white-space. ) allows multiple statements on the single line given that neither statement starts a new code block. def. possibly with a comment. Compound or complex statements. Multiple Statements on a Single Line: The semicolon ( . and class. Header lines begin the statement (with the keyword) and terminate with a colon ( : ) and are followed by one or more lines which make up the suite. Waiting for the User: The following line of the program displays the prompt. Press the enter key to exit. Once the user presses the key. the program ends. In an interactive interpreter session. and then waits for the user to press the Enter key: #!/usr/bin/python raw_input("\n\nPress the enter key to exit. Here is a sample snip using the semicolon: import sys.
this will produce following result: 100 1000. While running this program. The equal sign (=) is used to assign values to variables. respectively. The declaration happens automatically when you assign a value to a variable. The variable is stored as an object. For example: #!/usr/bin/python counter = 100 miles = 1000. This means that when you create a variable you reserve some space in memory. or characters in these variables.0 name = "John" print counter print miles print name Here 100. value and data type. by assigning different data types to variables. Therefore. and the operand to the right of the = operator is the value stored in the variable. Based on the data type of a variable. Python code number = 1 name value data type int greeting = "hello" greeting "hello" string number 1 The operand to the left of the = operator is the name of the variable. you can store integers. decimals. the interpreter allocates memory and decides what can be stored in the reserved memory. miles and name variables.Game Scripting with Python – Tim Glasser suite Variables Variables are nothing but reserved memory locations to store values. Assigning Values to Variables: Python variables do not have to be explicitly declared to reserve memory space.0 and "John" are the values assigned to counter. the object has a name.0 John # An integer assignment # A floating point # A string 18 . 1000.
For example: a=b=c=1 Here. and all three variables are assigned to the same memory location. Simple Data Types: The data stored in memory can be of many types. and one string object with the value "john" is assigned to the variable c. which mean that changing the value of a number data type results in a newly allocated object. c = 1.s age is stored as a numeric value and his or her address is stored as alphanumeric characters. Python has five standard data types: Numbers String List Tuple Dictionary Python Numbers: Number data types store numeric values. a person. Python has some standard types that are used to define the operations possible on them and the storage method for each of them. They are immutable data types. 2. "john" Here two integer objects with values 1 and 2 are assigned to variables a and b. For example: a. b.Game Scripting with Python – Tim Glasser Multiple Assignments: You can also assign a single value to several variables simultaneously. You can also assign multiple objects to multiple variables. The syntax of the del statement is: 19 . For example. an integer object is created with the value 1. Number objects are created when you assign a value to them. For example: var1 = 1 var2 = 10 You can also delete the reference to a number object by using the del statement.
var2[. Sequence Data Types Strings: 20 .varN]]]] You can delete a single object or multiple objects by using the del statement.. A complex number consists of an ordered pair of real floatingpoint numbers denoted by a + bj.j 9.0 15.53e-7j Python allows you to use a lowercase L with long.3+e18 -90. where a is the real part and b is the imaginary part of the complex number.. -32.6545+0J 3e+26J 4..54e100 70.14j 45. Python displays long integers with an uppercase L.Game Scripting with Python – Tim Glasser del var1[.var3[..322e-36j . but it is recommended that you use only an uppercase L to avoid confusion with the number 1.9 32.2-E12 float complex 3.20 -21. For example: del var del var_a. var_b Python supports four different numerical types: int (signed integers) long (long integers [can also be represented in octal and hexadecimal]) float (floating point real values) complex (complex numbers) Examples: Here are some examples of numbers: Int 10 100 -786 080 -0490 -0x260 0x69 51924361L -0x19323L 0122L 0xDEFABCECBDAECBFBAEl 535633629843L -052318172735L -4721885298529L long 0.876j -.
A list contains items separated by commas and enclosed within square brackets ([]). The plus ( + ) sign is the list concatenation operator. and the asterisk ( * ) is the repetition operator. To some extent.Game Scripting with Python – Tim Glasser Strings in Python are identified as a contiguous set of characters in between quotation marks. One difference between them is that all the items belonging to a list can be of different data type. The plus ( + ) sign is the string concatenation operator. Subsets of strings can be taken using the slice operator ( [ ] and [ : ] ) with indexes starting at 0 in the beginning of the string and working their way from -1 at the end. Python allows for either pairs of single or double quotes. Example: #!/usr/bin/python str = 'Hello World!' print str # Prints complete string print str[0] # Prints first character of the string print str[2:5] # Prints characters starting from 3rd to 6th print str[2:] # Prints string starting from 3rd character print str * 2 # Prints string two times print str + "TEST" # Prints concatenated string This will produce following result: Hello World! H llo llo World! Hello World!Hello World! Hello World!TEST Python Lists: Lists are the most versatile of Python's compound data types. lists are similar to arrays in C. and the asterisk ( * ) is the repetition operator. 21 . The values stored in a list can be accessed using the slice operator ( [ ] and [ : ] ) with indexes starting at 0 in the beginning of the list and working their way to end-1.
Game Scripting with Python – Tim Glasser Example: #!/usr/bin/python list = [ 'abcd'. 'john'] print list # Prints complete list print list[0] # Prints first element of the list print list[1:3] # Prints elements starting from 2nd to 4th print list[2:] # Prints elements starting from 3rd element print tinylist * 2 # Prints list two times print list + tinylist # Prints concatenated lists This will produce following result: ['abcd'. 70. however. 70. 'john'] ['abcd'. 'john'. tuples are enclosed within parentheses. 'john') print tuple # Prints complete list print tuple[0] # Prints first element of the list print tuple[1:3] # Prints elements starting from 2nd to 4th print tuple[2:] # Prints elements starting from 3rd element print tinytuple * 2 # Prints list two times 22 . 2.23. while tuples are enclosed in parentheses ( ( ) ) and cannot be updated. 'john'. 'john'. 786.2 ] tinylist = [123.23] [2.200000000000003] [123. 'john'.23. 'john'.2 ) tinytuple = (123.23. 2. 70.200000000000003. 2. 'john'] Python Tuples: A tuple is another sequence data type that is similar to the list. The main differences between lists and tuples are: Lists are enclosed in brackets ( [ ] ). and their elements and size can be changed. Tuples can be thought of as read-only lists. 786 . 123. Example: #!/usr/bin/python tuple = ( 'abcd'. 786. A tuple consists of a number of values separated by commas. 786 .200000000000003] abcd [786.23. 70. 2. 123. 2. 'john'.23. Unlike lists. 70.
'john') ('abcd'. 70. 786.200000000000003) (123. but are usually numbers or strings. 123. 70.2 ] tuple[2] = 1000 # Invalid syntax with tuple list[2] = 1000 # Valid syntax with list Python Dictionary: Python 's dictionaries are hash table type. 786.'code':6734. 2. 2.200000000000003) abcd (786. 70. 2. 'dept': 'sales'} print dict['one'] # Prints value for 'one' key 23 . 2. Keys can be almost any Python type. 'john'. 'john'. Example: #!/usr/bin/python dict = {} dict['one'] = "This is one" dict[2] = "This is two" tinydict = {'name': 'john'. 'john'.23.23. 786 .2 ) list = [ 'abcd'. because we attempted to update a tuple. 70.23) (2. 'john'. Values. 70.23. They work like associative arrays and consist of key-value pairs. 2. 123. 'john') Following is invalid with tuple. on the other hand. can be any arbitrary Python object. 'john'. 786 . 'john'.200000000000003.23. Dictionaries are enclosed by curly braces ( { } ) and values can be assigned and accessed using square braces ( [] ).which is not allowed.23. Similar case is possible with lists: #!/usr/bin/python tuple = ( 'abcd'.Game Scripting with Python – Tim Glasser print tuple + tinytuple # Prints concatenated lists This will produce following result: ('abcd'.
24 . Converts s to a tuple. Converts x to a floating-point number.Game Scripting with Python – Tim Glasser print dict[2] # Prints value for 2 key print tinydict # Prints complete dictionary print tinydict.imag]) str(x) repr(x) eval(str) tuple(s) list(s) set(s) dict(d) Description Converts x to an integer. 'name'] ['sales'. It is incorrect to say that the elements are "out of order". Creates a complex number. Evaluates a string and returns an object. 'name': 'john'} ['dept'. Creates a dictionary. base specifies the base if x is a string. Converts x to a long integer. Function int(x [. Data Type Conversion: Sometimes you may need to perform conversions between the built-in types.base] ) float(x) complex(real [. 'code': 6734. base specifies the base if x is a string. d must be a sequence of (key.base]) long(x [. There are several built-in functions to perform conversion from one data type to another. 6734.values() # Prints all the values This will produce following result: This is one This is two {'dept': 'sales'. To convert between types you simply use the type name as a function. 'john'] Dictionaries have no concept of order among elements. 'code'. Converts s to a set. These functions return a new object representing the converted value. Converts object x to a string representation.value) tuples. Converts s to a list. Converts object x to an expression string.keys() # Prints all the keys print tinydict. they are simply unordered.
Subtracts right hand operand from left hand operand Multiplication . Converts an integer to an octal string. Converts a single character to its integer value.Adds values on either side of the operator Subtraction . Python Arithmetic Operators: Assume variable a holds 10 and variable b holds 20 then: Operator + * / % Description Addition . Arithmetic Operators Comparision Operators Logical (or Relational) Operators Assignment Operators Conditional (or ternary) Operators Lets have a look on all operators one by one. Converts an integer to a Unicode character.Divides left hand operand by right hand operand and returns Example a + b will give 30 a .Divides left hand operand by right hand operand Modulus .b will give -10 a * b will give 200 b / a will give 2 b % a will give 0 25 . Converts an integer to a character. Converts an integer to a hexadecimal string.Game Scripting with Python – Tim Glasser frozenset(s) chr(x) unichr(x) ord(x) hex(x) oct(x) Converts s to a frozen set. Python language supports following type of operators. Here 4 and 5 are called operands and + is called operator.Multiplies values on either side of the operator Division . Operators What is an operator? Simple answer can be given using expression 4 + 5 is equal to 9.
0 is equal to 4. This is similar to != operator. <= Checks if the value of left operand is less than or equal to the value of right (a <= b) is true. Checks if the value of left operand is greater than or equal to the value of right operand.Game Scripting with Python – Tim Glasser remainder ** Exponent .The division of operands where the result is the quotient in which the digits after the decimal point are removed. if yes then condition becomes true.Performs exponential (power) calculation on operators Floor Division . Example (a == b) is not true. <> (a <> b) is true.0//2. if yes then condition 26 . > (a > b) is not true. if (a < b) is true.0 Python Comparison Operators: Assume variable a holds 10 and variable b holds 20 then: Operator == Description Checks if the value of two operands are equal or not. Checks if the value of two operands are equal or not. if yes then condition becomes true. Checks if the value of left operand is greater than the value of right operand. if values are not equal then condition becomes true. a**b will give 10 to the power 20 // 9//2 is equal to 4 and 9. >= (a >= b) is not true. yes then condition becomes true. if values are not equal then condition becomes true. < Checks if the value of left operand is less than the value of right operand. Checks if the value of two operands are equal or not. != (a != b) is true. operand. if yes then condition becomes true.
Performs floor division on c //= a is equivalent to c = c // a operators and assign value to the left operand 27 . Performs exponential (power) calculation on operators and assign value to the left operand /= %= c %= a is equivalent to c = c % a **= c **= a is equivalent to c = c ** a //= Floor Dividion and assigns a value.Game Scripting with Python – Tim Glasser becomes true. It adds right operand to the left operand and assign the result to left operand Subtract AND assignment operator. Assigns values from right side operands to left side operand Add AND assignment operator. It multiplies right c *= a is equivalent to c = c * a operand with the left operand and assign the result to left operand Divide AND assignment operator. It takes modulus using two operands and assign the result to left operand Exponent AND assignment operator. It subtracts right operand from the left operand and assign the result to left operand Example c = a + b will assigne value of a + b into c += c += a is equivalent to c = c + a -= c -= a is equivalent to c = c – a *= Multiply AND assignment operator. It divides left operand c /= a is equivalent to c = c / a with the right operand and assign the result to left operand Modulus AND assignment operator. Python Assignment Operators: Assume variable a holds 10 and variable b holds 20 then: Operator = Description Simple assignment operator.
Evaluates to true if it finds a variable in the specified sequence and false otherwise. such as strings. Called Logical OR Operator. here not in results in a 1 if x is a member of sequence y. Called Logical NOT Operator. which test for membership in a sequence. here in results in a 1 if x is a member of sequence y. not in Python Identity Operators: Identity operators compare the memory locations of two objects. Example x in y. Logical NOT operator will make false. then condition becomes true. or not Python Membership Operators: In addition to the operators discussed previously. Python has membership operators. condition becomes true. There are two membership operators explained below: Operator in Description Evaluates to true if it finds a variable in the specified sequence and false otherwise. lists. Use to reverses the logical state of its operand. If a condition is true then not(a && b) is false. or tuples.Game Scripting with Python – Tim Glasser Python Logical Operators: There are following logical operators supported by Python language Assume variable a holds 10 and variable b holds 20 then: Operator and Description Example Called Logical AND operator. If both the operands are true then then (a and b) is true. x not in y. There are two Identity operators explained below: Operator Description Example 28 . If any of the two operands are non zero then (a or b) is true.
Game Scripting with Python – Tim Glasser Evaluates to true if the variables on x is y. is is not Python Operators Precedence The following table lists all operators from highest precedence to lowest. divide. same object and true otherwise. Operator ** ~+* / % // +>> << & ^| <= < > >= <> == != Description Exponentiation (raise to the power) Ccomplement. The program should • Ask the user to input the lengths of the sides of the rectangle • Compute the area – Area = length * width 29 . here is results in 1 if id(x) either side of the operator point to the equals id(y). Evaluates to false if the variables on x is not y. unary plus and minus (method names for the last two are +@ and -@) Multiply. here is not results in 1 if either side of the operator point to the id(x) is not equal to id(y). modulo and floor division Addition and subtraction Right and left bitwise shift Bitwise 'AND' Bitwise exclusive `OR' and regular `OR' Comparison operators Equality operators = %= /= //= -= += |= &= >>= Assignment operators <<= *= **= is is not in not in note or and Identity operators Membership operators Logical operators Exercises: 1. Create a program that will compute the area of a rectangle. same object and false otherwise.
Pretend that your program should act like a cash register. Create the following output (assuming "red" is the chosen color). Pass in 3 arguments ( string . and the amount paid. Use "+" and "*". Write a program to calculate compound interest. and then swaps them. Write a program that asks the user to input values for two floating point numbers. The formula for compound interest is : Amount = Current Value * ( 1 + Rate of Interest) ** n (where n is the number compounding periods) 6.Game Scripting with Python – Tim Glasser • Display the result 2. 3. Write a program that asks users for their favorite color. and then responds with the amount of change. float and integer) to a Python script. Hint: you may need more than two variables for this to work. It should prompt the user for two values – the total cost of items. The script prints the arguments out an also adds the float and integer together and prints out the result 30 . The program should then display the values. red red red red red red red red red red red red red red red red red red red red red red red red 7. 5.
all the statements indented by the same number of character spaces after a programming construct are considered to be part of a single block of code. and nested if.else. Note: In Python. if its value is nonzero then the statement(s) block are executed. elif. This tutorial will discuss the programming conditional constructs available in Python.Got a true expression value" print var1 var2 = 0 if var2: print "2 . and a decision is made based on the result of the comparison.. The if statement contains a logical expression using which data is compared. The result of this decision making determines the sequence in which a program will execute instructions. You can control the flow of a program by using conditional constructs. condition is evaluated first. If condition is true that is. Otherwise.Got a true expression value" print var2 print "Good bye!" 31 . The if statement: The if statement of Python is similar to that of other languages. the next statement following the statement(s) block is executed. if. such as if. Example: #!/usr/bin/python var1 = 100 if var1: print "1 ..Game Scripting with Python – Tim Glasser Week 3 Control Structures Conditional constructs are used to incorporate decision making into programs. Python uses indentation as its method of grouping statements. The syntax of the if statement is: if expression: statement(s) Here if statement.
else statement is: if expression: statement(s) else: statement(s) Example: #!/usr/bin/python var1 = 100 if var1: print "1 .Got a false expression value" print var2 print "Good bye!" This will produce following result: 32 . The else statement is an optional statement and there could be at most only one else statement following if .Got a false expression value" print var1 var2 = 0 if var2: print "2 .Got a true expression value 100 Good bye! The else Statement: An else statement can be combined with an if statement.Game Scripting with Python – Tim Glasser This will produce following result: 1 ..Got a true expression value" print var1 else: print "1 ..Got a true expression value" print var2 else: print "2 . An else statement contains the block of code that executes if the conditional expression in the if statement resolves to 0 or a false value. The syntax of the if.
Got a true expression value" print var elif var == 150: print "2 .Got a false expression value" print var 33 .. Example: #!/usr/bin/python var = 100 if var == 200: print "1 ..Got a false expression value 0 Good bye! The elif Statement The elif statement allows you to check multiple expressions for truth value and execute a block of code as soon as one of the conditions evaluates to true. However. there can be an arbitrary number of elif statements following an if.Got a true expression value 100 2 .Got a true expression value" print var else: print "4 . The syntax of the if.Game Scripting with Python – Tim Glasser 1 . the elif statement is optional.Got a true expression value" print var2 elif var == 100: print "3 .elif statement is: if expression1: statement(s) elif expression2: statement(s) elif expression3: statement(s) else: statement(s) Note: Python does not currently support switch or case statements as in other languages. for which there can be at most one statement. Like the else. unlike else.
.else construct inside another if. The syntax of the nested if.elif.. In a nested if construct.. you can have an if...elif.Game Scripting with Python – Tim Glasser print "Good bye!" This will produce following result: 3 ...elif..Got a true expression value 100 Good bye! The Nested if. you can use the nested if construct..else construct may be:: 34 .else Construct There may be a situation when you want to check for another condition after a condition resolves to true....else construct..elif... In such a situation..
The while Loop: The while loop is just one of the looping constructs available in Python. The expression has to be a logical expression and must return either a true or a false value The syntax of the while look is: while expression: statement(s) 35 . When the condition becomes false. the while loop continues until the expression becomes false. This tutorial will discuss the while loop construct available in Python. it may go on the same line as the header statement: Here is an example of a one-line if clause: if ( expression == 1 ) : print "Value of expression is 1" Loops A loop is a construct that causes a section of a program to be repeated a certain number of times. the loop ends and the program control is passed to the statement following the loop. The repetition continues while the condition set for the loop remains true.Game Scripting with Python – Tim Glasser print "Expression value is less than 50" else: print "Could not find true expression" print "Good bye!" This will produce following result: Expression value is less than 200 Which is 100 Good bye! Single Statement Suites: If the suite of an if clause consists only of a single line.
all the statements indented by the same number of character spaces after a programming construct are considered to be part of a single block of code. If expression is true that is. 36 . Note: In Python. count count = count + 1 print "Good bye!" This will produce following result: The count is: 0 The count is: 1 The count is: 2 The count is: 3 The count is: 4 The count is: 5 The count is: 6 The count is: 7 The count is: 8 Good bye! The block here. the next statement following the statement(s) block is executed. This results in a loop that never ends. consisting of the print and increment statements. Example: #!/usr/bin/python count = 0 while (count < 9): print 'The count is:'.Game Scripting with Python – Tim Glasser Here expression statement is evaluated first. Python uses indentation as its method of grouping statements. Otherwise. then the statement(s) block is executed repeatedly until expression becomes false. An infinite loop might be useful in client/server programming where the server needs to run continuously so that client programs can communicate with it as and when required. With each iteration. The Infinite Loops: You must use caution when using while loops because of the possibility that this condition never resolves to a false value. the current value of the index count is displayed and then increased by 1. is executed repeatedly until count is no longer less than 9. Such a loop is called an infinite loop.
Game Scripting with Python – Tim Glasser Example: Following loop will continue till you enter 1 at command prompt: #!/usr/bin/python var = 1 while var == 1 : # This constructs an infinite loop num = raw_input("Enter a number :") print "You entered: ". num print "Good bye!" This will produce following result: Enter a number :20 You entered: 20 Enter a number :29 You entered: 29 Enter a number :3 You entered: 3 Enter a number between :Traceback (most recent call last): File "test. Here is an example of a one-line while clause: while expression : statement The for Loop: The for loop in Python has the ability to iterate over the items of any sequence. such as a list or a string. in <module> num = raw_input("Enter a number :") KeyboardInterrupt Above example will go in an infinite loop and you would need to use CNTL+C to come out of the program. Single Statement Suites: Similar to the if statement syntax. The syntax of the loop look is: 37 . line 5. if your while clause consists only of a single statement.py". it may be placed on the same line as the while header.
Then. fruit print "Good bye!" This will produce: Example: 38 .Game Scripting with Python – Tim Glasser for iterating_var in sequence: statements(s) If a sequence contains an expression list. letter fruits = ['banana'. Note: In Python. 'apple'. the statements block is executed. Each item in the list is assigned to iterating_var. Next. all the statements indented by the same number of character spaces after a programming construct are considered to be part of a single block of code. 'mango'] for fruit in fruits: # Second Example print 'Current fruit :'. Python uses indentation as its method of grouping statements. Example: #!/usr/bin/python for letter in 'Python': # First Example print 'Current Letter :'. it is evaluated first. the first item in the sequence is assigned to the iterating variable iterating_var. and the statements(s) block is executed until the entire sequence is exhausted.
letter 39 . Example: #!/usr/bin/python for letter in 'Python': # First Example if letter == 'h': break print 'Current Letter :'. The break statement can be used in both while and for loops. 'apple'. You might face a situation in which you need to exit a loop completely when an external condition is triggered or there may also be a situation when you want to skip a part of the loop and start next execution. fruits[index] print "Good bye!" This will produce following result: Current fruit : banana Current fruit : apple Current fruit : mango Good bye! Here we took the assistance of the len() built-in function. This tutorial will discuss the break. continue and pass statements available in Python. The most common use for break is when some external condition is triggered requiring a hasty exit from a loop.Game Scripting with Python – Tim Glasser #!/usr/bin/python fruits = ['banana'. just like the traditional break found in C. 'mango'] for index in range(len(fruits)): print 'Current fruit :'. which provides the total number of elements in the tuple as well as the range() built-in function to give us the actual sequence to iterate over. The break Statement: The break statement in Python terminates the current loop and resumes execution at the next statement. Python provides break and continue statements to handle such situations and to have good control on your loop.
letter var = 10 # Second Example while var > 0: print 'Current variable value :'. Example: #!/usr/bin/python for letter in 'Python': # First Example if letter == 'h': continue print 'Current Letter :'.Game Scripting with Python – Tim Glasser var = 10 # Second Example while var > 0: print 'Current variable value :'. var var = var -1 if var == 5: continue 40 . The continue statement can be used in both while and for loops. The continue statement rejects all the remaining statements in the current iteration of the loop and moves the control back to the top of the loop. var var = var -1 if var == 5: break print "Good bye!" This will produce following result: Current Letter : P Current Letter : y Current Letter : t Current variable value : 10 Current variable value : 9 Current variable value : 8 Current variable value : 7 Current variable value : 6 Good bye! The continue Statement: The continue statement in Python returns the control to the beginning of the while loop.
the #first FOR else: # else part of the loop 41 . the else statement is executed when the condition becomes false. If the else statement is used with a while loop.num): #to iterate on the factors of the number if num%i == 0: #to determine the first factor j=num/i #to calculate the second factor print '%d equals %d * %d' % (num.i.Game Scripting with Python – Tim Glasser print "Good bye!" This will produce following result: Current Letter : P Current Letter : y Current Letter : t Current Letter : o Current Letter : n Current variable value : 10 Current variable value : 9 Current variable value : 8 Current variable value : 7 Current variable value : 6 Current variable value : 5 Current variable value : 4 Current variable value : 3 Current variable value : 2 Current variable value : 1 Good bye! The else Statement Used with Loops Python supports to have an else statement associated with a loop statements.20): #to iterate between 10 to 20 for i in range(2. If the else statement is used with a for loop. Example: The following example illustrates the combination of an else statement with a for statement that searches for prime numbers from 10 through 20. #!/usr/bin/python for num in range(10.j) break #to move to the next number. the else statement is executed when the loop has exhausted iterating the list.
in stubs for example): Example: #!/usr/bin/python for letter in 'Python': if letter == 'h': pass print 'This is pass block' print 'Current Letter :'.Game Scripting with Python – Tim Glasser print num. letter print "Good bye!" This will produce following result: Current Letter : P Current Letter : y Current Letter : t This is pass block 42 . The pass statement is a null operation. 'is a prime number' This will produce following result: 10 equals 2 * 5 11 is a prime number 12 equals 2 * 6 13 is a prime number 14 equals 2 * 7 15 equals 3 * 5 16 equals 2 * 8 17 is a prime number 18 equals 2 * 9 19 is a prime number Similar way you can use else statement with while loop. nothing happens when it executes. but has not been written yet (e.g. The pass Statement: The pass statement in Python is used when a statement is required syntactically but you do not want any command or code to execute. The pass is also useful in places where your code will eventually go..
Output a message telling them if they were correct or not. Ask the user what the password is once. 2. Use Python strings. You can then remove the statements inside the block but let the block remain with a pass statement so that it doesn't interfere with other parts of the code. Choose a word and store it into a string. Write a program that will find the square root of a number that the user enters. 9. Keep asking them to guess the word until they get the correct answer ( use a while loop). 3. until the user enters a ‘q’ or ‘Q’. Write a program that will loop. It should first ask for two numbers (double). Exercises: 1. Ask the user to input a single character. Rewrite #2 so that it loops continuously until the user enters the correct password. Imagine that you are writing the beginning of a hangman program. subtraction. multiplication and division). then prompt the user for a calculation (char) and use a switch statement to complete the operations. Write a program that acts like a four-function calculator (addition. Create a program that uses a “for” loop to print out the numbers 1-50. The pass statement is helpful when you have created a code block but it is no longer required. 8. 7. 5. and display a message that they either logged in correctly or incorrectly.Game Scripting with Python – Tim Glasser Current Letter : h Current Letter : o Current Letter : n Good bye! The preceding code does not execute any statement or code if the value of letter is 'h'. 4. asking the user to input a single character. and then test to see if the character is a part of the string. Define the word at the top of the program. Write a program to have a user guess an entire word. 43 . Pretend that you program is a login for some service. Choose a word to be the password.
Syntax: def functionname( parameters ): "function_docstring" function_suite return [expression] By default. You can also define parameters inside these parentheses. The code block within every function starts with a colon (:) and is indented. A return statement with no arguments is the same as return None. and you need to inform them in the same order that they were defined. parameters have a positional behavior. Functions provides better modularity for your application and a high degree of code reusing. Defining a Function You can define functions to provide the required functionality. optionally passing back an expression to the caller. def printme( str ): "This prints a passed string into this function" print str return 44 . Example: Here is the simplest form of a Python function. reusable code that is used to perform a single. Python gives you many built-in functions like print() etc. The first statement of a function can be an optional statement . The statement return [expression] exits a function.the documentation string of the function or docstring. Any input parameters or arguments should be placed within these parentheses. but you can also create your own functions. As you already know. This function takes a string as input parameter and prints it on standard screen.Game Scripting with Python – Tim Glasser Week 4 Functions A function is a block of organized. related action. These functions are called user-defined functions. Here are simple rules to define a function in Python: • • • • • Function blocks begin with the keyword def followed by the function name and parentheses ( ( ) ).
3. printme("Again second call to the same function"). you can execute it by calling it from another function or directly from the Python prompt. It means if you change what a parameter refers to within a function. specifies the parameters that are to be included in the function.Game Scripting with Python – Tim Glasser Calling a Function Defining a function only gives it a name. # Now you can call printme function printme("I'm first call to user defined function!"). 45 .2. This would produce following result: I'm first call to user defined function! Again second call to the same function Pass by reference vs value Python passes function parameters using call-by-value. print "Values inside the function: ".4]). For example: #!/usr/bin/python # Function definition is here def changeme( mylist ): "This changes a passed list into this function" mylist. return. Following is the example to call printme() function: #!/usr/bin/python # Function definition is here def printme( str ): "This prints a passed string into this function" print str. the change does not affect the function's caller.append([1. mylist return # Now you can call changeme function mylist = [10.20. and structures the blocks of code. All parameters in the Python language are passed by reference. Once the basic structure of a function is finalized.30].
[1. 4]] Values outside the function: [10. that reference is being over-written. 2. [1. 3. mylist return # Now you can call changeme function mylist = [10. changeme( mylist ). 4] Values outside the function: [10. So this would produce following result: Values inside the function: [10.Game Scripting with Python – Tim Glasser changeme( mylist ). # This would assig new reference in mylist print "Values inside the function: ". mylist The parameter mylist is local to the function changeme. 20. print "Values outside the function: ".3. 20. 30] Function Arguments: You can call a function by using the following types of formal arguments:: • • • • Required arguments Keyword arguments Default arguments Variable-length arguments 46 .30]. 30. 3. 3. 20. 2. Changing mylist within the function does not affect mylist. 2. 30.20. 4]] There is one more example where argument is being passed by reference but inside the function. mylist Here we are maintaining reference of the passed object and appending values in the same object.2. print "Values outside the function: ". The function accomplishes nothing and finally this would produce following result: Values inside the function: [1. #!/usr/bin/python # Function definition is here def changeme( mylist ): "This changes a passed list into this function" mylist = [1.4].
47 . return. To call the function printme() you definitely need to pass one argument otherwise it would give a syntax error as follows: #!/usr/bin/python # Function definition is here def printme( str ): "This prints a passed string into this function" print str. in <module> printme(). line 11. TypeError: printme() takes exactly 1 argument (0 given) Keyword arguments: Keyword arguments are related to the function calls. return. # Now you can call printme function Printme().: #!/usr/bin/python # Function definition is here def printme( str ): "This prints a passed string into this function" print str.py".Game Scripting with Python – Tim Glasser Required arguments: Required arguments are the arguments passed to a function in correct positional order. This would produce following result: Traceback (most recent call last): File "test. Here the number of arguments in the function call should match exactly with the function definition. When you use keyword arguments in a function call.
48 . Following example gives idea on default arguments. it would print default age if it is not passed: #!/usr/bin/python # Function definition is here def printinfo( name. name. print "Age ". age. here order of the parameter does not matter: #!/usr/bin/python # Function definition is here def printinfo( name.Game Scripting with Python – Tim Glasser # Now you can call printme function Printme( str = "My string"). age. Note. return. return. age = 35 ): "This prints a passed info into this function" print "Name: ". This would produce following result: My string Following example gives more clear picture. print "Age ". age ): "This prints a passed info into this function" print "Name: ". This would produce following result: Name: miki Age 50 Default arguments: A default argument is an argument that assumes a default value if a value is not provided in the function call for that argument. name. name="miki" ). # Now you can call printinfo function printinfo( age=50.
printinfo( name="miki" ). This would produce following result: 49 . The general syntax for a function with non-keyword variable arguments is this: def functionname([formal_args.] *var_args_tuple ): "function_docstring" function_suite return [expression] An asterisk (*) is placed before the variable name that will hold the values of all nonkeyword variable arguments. This tuple remains empty if no additional arguments are specified during the function call. 50 ). # Now you can call printinfo function printinfo( 10 ). This would produce following result: Name: miki Age 50 Name: miki Age 35 Variable-length arguments: You may need to process a function for more arguments than you specified while defining the function. These arguments are called variable-length arguments and are not named in the function definition. For example: #!/usr/bin/python # Function definition is here def printinfo( arg1.Game Scripting with Python – Tim Glasser # Now you can call printinfo function printinfo( age=50. unlike required and default arguments. 60. printinfo( 70. *vartuple ): "This prints a variable passed arguments" print "Output is: " print arg1 for var in vartuple: print var return. name="miki" ).
An anonymous function cannot be a direct call to print because lambda requires an expression.. they are not equivalent to inline statements in C or C++. 20 ) This would produce following result: 50 .. Syntax: The syntax of lambda functions contains only a single statement. sum( 20. • • • • Lambda forms can take any number of arguments but return just one value in the form of an expression.. Although it appears that lambda's are a one-line version of a function.. arg2: arg1 + arg2. Lambda functions have their own local namespace and cannot access variables other than those in their parameter list and those in the global namespace. 20 ) print "Value of total : ". They cannot contain commands or multiple expressions. sum( 10. whose purpose is by passing function stack allocation during invocation for performance reasons.Game Scripting with Python – Tim Glasser Output is: 10 Output is: 70 60 50 The Anonymous Functions: You can use the lambda keyword to create small anonymous functions..arg2.argn]]:expression Example: Following is the example to show how lambda form of function works: #!/usr/bin/python # Function definition is here sum = lambda arg1. These functions are called anonymous because they are not declared in the standard manner by using the def keyword. which is as follows: Lambda [arg1 [. # Now you can call sum as a function print "Value of total : ".
Game Scripting with Python – Tim Glasser Value of total : 30 Value of total : 40 The follows: #!/usr/bin/python # Function definition is here def sum( arg1, arg2 ): # Add both the parameters and return them." total = arg1 + arg2 print "Inside the function : ", total return total; # Now you can call sum function total = sum( 10, 20 ); print "Outside the function : ", total This would produce following result: Inside the function : 30 Outside the function : 30:
• •
Global variables Local variables
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Game Scripting with Python – Tim Glasser
Global vs. Local Variables:. Example: #!/usr/bin/python This would produce following result: Inside the function local total : 30 Outside the function global total : 0
Exercises: 1. Write a program that uses a function to calculate the volume of a sphere, volume = 4/3r^3 . It should prompt the user for a radius, then display the result. 2. Rewrite #1 so that it will ask the user if they want to compute another volume, and quit if the answer is n or N. 3. Create functions to compute the area of a triangle, circle and rectangle correctly. 4. Use a debugger to see what happens when you run the program in #3.
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Game Scripting with Python – Tim Glasser 5. Write a program that uses an array to store 5 grades and add them. Create an error th in the array access so that it tries to access the 6 element of the array. Use a debugger to find the error. 6. Write two functions with the same name (overloaded function) that would both return an integer. If the function receives an integer, it should return the integer value. If it receives a string, it should return the length of the string. Here are the function prototypes long find_length(message) long find_length(number) 7. Imagine that you need a function that will check all of the elements of an array, and make them 0 if they are negative numbers. Test the function using an appropriate main function and array. 8. Use a debugger to see what happens when you run the program in #7.
9. Write a function that displays the times table of whatever number parameter it takes. Use this function to write the times tables up to 12
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var2[. with E or e indicating the power of 10 (2.var3[.. float (floating point real values) : or floats. var_b Python supports four different numerical types: int (signed integers): often called just integers or ints.5 x 102 = 250).. long (long integers ): or longs.322e-36j 54 .9 float complex 3.14j 45. which means that changing the value of a number data type results in a newly allocated object. They are an immutable data type. The syntax of the del statement is: del var1[. Here are some examples of numbers: int 10 100 -786 51924361L -0x19323L 0122L long 0.varN]]]] You can delete a single object or multiple objects by using the del statement.Game Scripting with Python – Tim Glasser Week 5: Numbers and Strings in Detail (midterm) Number data types store numeric values. For example: var1 = 1 var2 = 10 You can also delete the reference to a number object by using the del statement.5e2 = 2.. written like integers and followed by an uppercase or lowercase L.j 9. Number objects are created when you assign a value to them. For example: del var del var_a. complex (complex numbers) : Don’t worry about these types. represent real numbers and are written with a decimal point dividing the integer and fractional parts.0 15.20 -21. Floats may also be in scientific notation.. are positive or negative whole numbers with no decimal point. are integers of unlimited size.
-32. x and y are numeric expressions Built-in Number Functions: Mathematical Functions: Python includes following functions that perform mathematical calculations.3+e18 -90.53e-7j Python allows you to use a lowercase L with long. The floor of x: the largest integer not greater than x 55 . The ceiling of x: the smallest integer not less than x -1 if x < y. Type complex(x) to convert x to a complex number with real part x and imaginary part zero. or 1 if x > y The exponential of x: ex The absolute value of x. y) to convert x and y to a complex number with real part x and imaginary part y. Type float(x) to convert x to a floating-point number. Type long(x) to convert x to a long integer. 0 if x == y. Type complex(x. y) exp(x) fabs(x) floor(x) Returns ( description ) The absolute value of x: the (positive) distance between x and zero. Function abs(x) ceil(x) cmp(x. Type int(x)to convert x to a plain integer.Game Scripting with Python – Tim Glasser 080 -0490 -0x260 0x69 0xDEFABCECBDAECBFBAEl 535633629843L -052318172735L -4721885298529L 32. you'll need to coerce a number explicitly from one type to another to satisfy the requirements of an operator or function parameter.876j -. But sometimes. Number Type Conversion: Python converts numbers internally in an expression containing mixed types to a common type for evaluation. where a is the real part and b is the imaginary part of the complex number.6545+0J 3e+26J 4. A complex number consists of an ordered pair of real floatingpoint numbers denoted by a + bj.2-E12 . but it is recommended that you use only an uppercase L to avoid confusion with the number 1. Python displays long integers with an uppercase L.54e100 70.
x2. 56 .0 and round(-0.. tuple.5) is 1. A random float r. x2. Both parts have the same sign as x. The square root of x for x > 0 Random Number Functions: Random numbers are used for games. Function choice(seq) randrange ([start.. Python includes following functions that are commonly used.. The largest of its arguments: the value closest to positive infinity The smallest of its arguments: the value closest to negative infinity The fractional and integer parts of x in a two-item tuple.0..Game Scripting with Python – Tim Glasser log(x) log10(x) max(x1. security. stop. The value of x**y. Returns None. simulations. Returns None.) min(x1. and privacy applications. Python rounds away from zero as a tie-breaker: round(0.] stop [. for x> 0 The base-10 logarithm of x for x> 0 .) modf(x) pow(x.5) is 1.step]) random() Returns ( description ) A random item from a list..n]) sqrt(x) The natural logarithm of x. such that x is less than or equal to r and r is less than y seed([x]) shuffle(lst) uniform(x. Randomizes the items of a list in place. Call this function before calling any other random module function. step) A random float r. testing. or string.. such that 0 is less than or equal to r and r is less than 1 Sets the integer starting value used in generating random numbers. A randomly selected element from range(start. y) Trigonometric Functions: Python includes following functions that perform trigonometric calculations. y) round(x [. x rounded to n digits from the decimal point. The integer part is returned as a float.
Converts angle x from radians to degrees. Return the arc tangent of x. thus also considered a substring. Creating strings is as simple as assigning a value to a variable.Game Scripting with Python – Tim Glasser Function acos(x) asin(x) atan(x) atan2(y. in radians. Return the sine of x radians. these are treated as strings of length one. in radians. For example: var1 = 'Hello World!' var2 = "Python Programming" Accessing Values in Strings: Python does not support a character type. sqrt(x*x + y*y). y) sin(x) tan(x) degrees(x) radians(x) Description Return the arc cosine of x. Python treats single quotes the same as double quotes. Return the Euclidean norm. We can create them simply by enclosing characters in quotes. Return the arc sine of x. in radians. Return atan(y / x). The mathematical constant e. in radians. x) cos(x) hypot(x. Return the cosine of x radians. 57 . Mathematical Constants: The module also defines two mathematical constants: Constant pi e Description The mathematical constant pi. Return the tangent of x radians. Strings Strings are amongst the most popular types in Python. Converts angle x from degrees to radians.
". an escape character is preserved. an escape character is interpreted.Hello Python Escape Characters: Following table is a list of escape or non-printable characters that can be represented with backslash notation. Backslash Hexadecimal Description 58 . NOTE: In a double quoted string. in a single quoted string. var1[0] print "var2[1:5]: ". var2[1:5] This will produce following result: var1[0]: H var2[1:5]: ytho Updating Strings: You can "update" an existing string by (re)assigning a variable to another string. var1[:6] + 'Python' This will produce following result: Updated String :.Game Scripting with Python – Tim Glasser To access substrings. The new value can be related to its previous value or to a completely different string altogether. use the square brackets for slicing along with the index or indices to obtain your substring: Example: #!/usr/bin/python var1 = 'Hello World!' var2 = "Python Programming" print "var1[0]: ". Example: #!/usr/bin/python var1 = 'Hello World!' print "Updated String :.
7 Carriage return Space Tab Vertical tab Character x Hexadecimal notation.Returns true if a a*2 will give –HelloHello * [] [:] in a[1] will give e a[1:4] will give ell H in a will give 1 59 . concatenating multiple copies of the same string Slice .Adds values on either a + b will give HelloPython side of the operator Repetition .9. where n is in the range 0.F Concatenation .Gives the character from the given index Range Slice .Game Scripting with Python – Tim Glasser notation \a \b \cx \C-x \e \f \M-\C-x \n \nnn \r \s \t \v \x \xnn String Special Operators: Assume string variable a holds 'Hello' and variable b holds 'Python' then: Operator + Description Example 0x0d 0x20 0x09 0x0b 0x0a 0x1b 0x0c character 0x07 0x08 Bell or alert Backspace Control-x Control-x Escape Formfeed Meta-Control-x Newline Octal notation. a. where n is in the range 0.Creates new strings.f. or A.Gives the characters from the given range Membership .
" print r'\n' prints \n and print R'\n' which precedes the quotation marks. the letter "r. 21) This will produce following result: My name is Zara and weight is 21 kg! Here is the list of complete set of symbols which can be used along with %: Format Symbol %c %s %i %d Character string conversion via str() prior to formatting signed decimal integer signed decimal integer Conversion 60 . Format . Example: #!/usr/bin/python print "My name is %s and weight is %d kg!" % ('Zara'.Performs String formatting See at next section % String Formatting Operator: One of Python's coolest features is the string format operator %. The syntax for raw strings is exactly the same as for normal strings with the exception of the raw string operator.Game Scripting with Python – Tim Glasser character exists in the given string not in Membership .Suppress actual meaning of Escape characters.Returns true if a character does not exist in the given string M not in a will give 1 r/R Raw String . This operator is unique to strings and makes up for the pack of having functions from C's printf() family. prints \n The "r" can be lowercase (r) or uppercase (R) and must be placed immediately preceding the first quote mark.
and any other special characters. including verbatim NEWLINEs. #!/usr/bin/python Functionality Argument specifies width or precision left justification display the sign leave a blank space before a positive number add the octal leading zero ( '0' ) or hexadecimal leading '0x' or '0X'. Triple Quotes: Python's triple quotes comes to the rescue by allowing strings to span multiple lines. pad from left with zeros (instead of spaces) '%%' leaves you with a single literal '%' mapping variable (dictionary arguments) m is the minimum total width and n is the number of digits to display after the decimal point (if appl. depending on whether 'x' or 'X' were used.) 61 . TABs.Game Scripting with Python – Tim Glasser %u %o %x %X %e %E %f %g %G unsigned decimal integer octal integer hexadecimal integer (lowercase letters) hexadecimal integer (UPPERcase letters) exponential notation (with lowercase 'e') exponential notation (with UPPERcase 'E') floating point real number the shorter of %f and %e the shorter of %f and %E Other supported symbols and functionality are listed in the following table: Symbol * + <sp> # 0 % (var) m. The syntax for triple quotes consists of three consecutive single or double quotes.n.
Game Scripting with Python – Tim Glasser para_str = """this is a long string that is made up of several lines and non-printable characters such as TAB ( \t ) and they will show up that way when displayed. or just a NEWLINE within the variable assignment will also show up. """ print para_str. Also note that NEWLINEs occur either with an explicit carriage return at the end of a line or its escape code (\n): this is a long string that is made up of several lines and non-printable characters such as TAB ( ) and they will show up that way when displayed. NEWLINEs within the string." and closing triple quotes. Note how every single special character has been converted to its printed form. Every character you put into a raw string stays the way you wrote it: #!/usr/bin/python print 'C:\\nowhere' This would print following result: C:\nowhere Mow let's make use of raw string. whether explicitly given like this within the brackets [ ]. We would put expression in r'expression' as follows: #!/usr/bin/python print r'C:\\nowhere' This would print following result: 62 . right down to the last NEWLINE at the end of the string between the "up. NEWLINEs within the string. This will produce following result. whether explicitly given like this within the brackets [ \n ]. or just a NEWLINE within the variable assignment will also show up. Raw String: Raw strings don't treat the backslash as a special character at all.
end=len(string)) Determines if string or a substring of string (if starting index beg and ending index 2 3 3 4 5 63 . beg= 0. on error. default is to raise a ValueError unless errors is given with 'ignore' or 'replace'. fillchar) Returns a space-padded string with the original string centered to a total of width columns count(str.Game Scripting with Python – Tim Glasser C:\\nowhere Unicode String: Normal strings in Python are stored internally as 8-bit ASCII. encoding defaults to the default string encoding. or in a substring of string if starting index beg and ending index end are given decode(encoding='UTF-8'. while Unicode strings are stored as 16-bit Unicode. encode(encoding='UTF-8'.errors='strict') Decodes the string using the codec registered for encoding. world!' This would print following result: Hello. Built-in String Methods: Python includes following string methods: SN 1 Methods with Description capitalize() Capitalizes first letter of string center(width.end=len(string)) Counts how many times str occurs in string. endswith(suffix. Unicode strings use the prefix u.errors='strict') Returns encoded string version of string. I'll restrict my treatment of Unicode strings to the following: #!/usr/bin/python print u'Hello. including special characters from most languages in the world. This allows for a more varied set of characters. world! As you can see. just as raw strings use the prefix r. beg=0.
defaults to 8 spaces per tab if tabsize not provided find(str. returns index if found and -1 otherwise index(str. end=len(string)) Same as find(). and false otherwise 6 expandtabs(tabsize=8) Expands tabs in string to multiple spaces. or in a substring of string if starting index beg and ending index end are given. with separator string 18 len(string) Returns the length of the string ljust(width[. beg=0. fillchar]) 19 Returns a space-padded string with the original string left-justified to a total of width columns 64 . but raises an exception if str not found isa1num() Returns true if string has at least 1 character and all characters are alphanumeric and false otherwise 7 8 9 isalpha() 10 Returns true if string has at least 1 character and all characters are alphabetic and false otherwise 11 isdigit() Returns true if string contains only digits and false otherwise islower() 12 Returns true if string has at least 1 cased character and all cased characters are in lowercase and false otherwise 13 14 15 isnumeric() Returns true if string contains only numeric characters and false otherwise isspace() Returns true if string contains only whitespace characters and false otherwise istitle() Returns true if string is properly "titlecased" and false otherwise isupper() 16 Returns true if string has at least one cased character and all cased characters are in uppercase and false otherwise join(seq) 17 Merges (concatenates) the string representations of elements in sequence seq into a string. beg=0 end=len(string)) Determine if str occurs in string.Game Scripting with Python – Tim Glasser end are given) ends with suffix. Returns true if so.
new [. 29 rstrip() Removes all trailing whitespace of string split(str="". but search backwards in string rindex( str. beg=0.count(str)) 30 Splits string according to delimiter str (space if not provided) and returns list of substrings. max(str) Returns the max alphabetical character from the string str min(str) Returns the min alphabetical character from the string str 20 21 22 23 24 replace(old. num=string. end=len(string)) Same as index().Game Scripting with Python – Tim Glasser lower() Converts all uppercase letters in string to lowercase lstrip() Removes all leading whitespace in string maketrans() Returns a translation table to be used in translate function.[. max]) 25 Replaces all occurrences of old in string with new. or at most max occurrences if max given 26 27 rfind(str. Returns true if so. beg=0. all words begin with uppercase.end=len(string)) Same as find(). and the 65 . fillchar]) 28 Returns a space-padded string with the original string right-justified to a total of width columns. but search backwards in string rjust(width.count('\n')) 31 Splits string at all (or num) NEWLINEs and returns a list of each line with NEWLINEs removed startswith(str. and false otherwise 33 34 35 strip([chars]) Performs both lstrip() and rstrip() on string swapcase() Inverts case for all letters in string title() Returns "titlecased" version of string.end=len(string)) 32 Determines if string or a substring of string (if starting index beg and ending index end are given) starts with substring str. split into at most num substrings if given splitlines( num=string. beg=0. that is.
(Hint: if a variable is empty. last name and phone number.) 3) Change the script so that the script prints "Thank you" if either the first name or the last name or the phone number is supplied. its value will be "false". then remove the last five letters from the name and print it out 66 . zfill() retains any sign given (less one zero) Exercises 1) Ask the user to enter a string and print it back in Upper Case. intended for numbers. removing those in the del string 37 upper() Converts lowercase letters in string to uppercase zfill (width) 38 Returns original string leftpadded with zeros to a total of width characters. i 2) Write a script that asks someone to input their first name. 4) Change the script so that only first name and last name are required. If the user does not type at least some characters for each of these. print "Do not leave any fields empty" otherwise print "Thank you". 5) Ask the user to enter their name. deletechars="") 36 Translates string according to translation table str(256 chars). Print "Do not leave all fields empty" otherwise. The phone number is optional.Game Scripting with Python – Tim Glasser rest are lowercase translate(table.
3. 2000]. "b". use the square brackets for slicing along with the index or indices to obtain value available at that index: Example: #!/usr/bin/python list1 = ['physics'. The first index is zero. list2[1:5] 67 . 2000]. 4. Good thing about a list that items in a list need not all have the same type: Creating a list is as simple as putting different comma-separated values between square brackets. There are certain things you can do with all sequence types. Accessing Values in Lists: To access values in lists. 6. 3. dictionaries. 2. Python has built-in functions for finding the length of a sequence. list indices start at 0. slicing. These operations include indexing. the second index is one.its position. 1997. and checking for membership. adding. list2 = [1. Python has six built-in types of sequences (strings. In addition. "c".Game Scripting with Python – Tim Glasser Week 6 More Sequence Types – Lists. 2. "d"]. tuples. multiplying. lists. and so forth. and for finding its largest and smallest elements. 'chemistry'. Python Lists: The list is a most versatile data type available in Python. list1[0] print "list2[1:5]: ". 4. or index. 7 ]. list2 = [1. 1997. print "list1[0]: ". Like string indices. Tuples and Dictionaries The most basic data structure in Python is the sequence. list3 = ["a". 5 ]. Each element of a sequence is assigned a number . For example: list1 = ['physics'. which can be written as a list of comma-separated values (items) between square brackets. concatenated and so on. and lists can be sliced. 'chemistry'. etc) but the most common ones are lists and tuples which we will see in this tutorial. 5.
1997. print "Value available at index 2 : " print list1[2]. 1997. 68 . del list1[2]. 2000]. Example: #!/usr/bin/python list1 = ['physics'. Note: append() method is discussed in subsequent section. you can use either the del statement if you know exactly which element(s) you are deleting or the remove() method if you do not know. print list1. list1[2] = 2001. and you can add to elements in a list with the append() method: Example: #!/usr/bin/python list1 = ['physics'. 3.Game Scripting with Python – Tim Glasser This will produce following result: list1[0]: physics list2[1:5]: [2. 2000]. 'chemistry'. print "New value available at index 2 : " print list1[2]. This will produce following result: Value available at index 2 : 1997 New value available at index 2 : 2001 Delete List Elements: To remove a list element. 5] Updating Lists: You can update single or multiple elements of lists by giving the slice on the left-hand side of the assignment operator. 'chemistry'. 4.
3] + [4. 2000] Note: remove() method is discussed in subsequent section. 2. indexing and slicing work the same way for lists as they do for strings. 3]: print x. 'Hi!'. This will produce following result: ['physics'. 3]) [1. lists respond to all of the general sequence operations we used on strings in the prior chapter : Python Expression len([1. 2. 'chemistry'. 'SPAM!'] Python Expression L[2] L[-2] 'SPAM!' 'Spam' Results Description Offsets start at zero Negative: count from the right 69 . 6] ['Hi!'. 'Hi!'. In fact. 3. 5. 2.Game Scripting with Python – Tim Glasser print "After deleting value at index 2 : " print list1. Assuming following input: L = ['spam'. 4. 'chemistry'. and Matrixes: Because lists are sequences. 2000] After deleting value at index 2 : ['physics'. 1997. 3] for x in [1. 2. 2. Slicing. not a string. 6] ['Hi!'] * 4 3 in [1. except that the result is a new list. 3 [1. 'Hi!'] True 123 Results Length Concatenation Repetition Membership Iteration Description Indexing. Basic List Operations: Lists respond to the + and * operators much like strings. 'Spam'. they mean concatenation and repetition here too. 5.
list2) Compares elements of both lists.append(obj) Appends object obj to list list. Python includes following list methods SN 1 2 3 4 5 6 7 8 list. list(seq) Converts a tuple into list.extend(seq) Appends the contents of seq to list list.reverse() Reverses objects of list in place Methods with Description 70 .count(obj) Returns count of how many times obj occurs in list list.Game Scripting with Python – Tim Glasser L[1:] ['Spam'.pop(obj=list[-1]) Removes and returns last object or obj from list list.insert(index.remove(obj) Removes object obj from list list. 'SPAM!'] Slicing fetches sections Built-in List Functions & Methods: Python includes following list functions SN 1 2 3 4 5 Function with Description cmp(list1. max(list) Returns item from the list with max value.index(obj) Returns the lowest index in list that obj appears list. len(list) Gives the total length of the list. obj) Inserts object obj into list at offset index list. min(list) Returns item from the list with min value.
'chemistry'. 7 ). For example: tup1 = ('physics'. tuple indices start at 0. 4. 6. tuples are immutable and tuples use parentheses and lists use square brackets. Creating a tuple is as simple as putting different comma-separated values and optionally you can put these comma-separated values between parentheses also.e. tup3 = "a". tup2 = (1. "b". 3. 5 ). 2. and tuples can be sliced. 4. To write a tuple containing a single value you have to include a comma. Tuples are sequences. "d". 3. tup2[1:5] 71 . The empty tuple is written as two parentheses containing nothing: Tup1 = ().Game Scripting with Python – Tim Glasser list. 2000). tup2 = (1. tup1[0] print "tup2[1:5]: ".sort([func]) Sorts objects of list. 2000). 1997. 5. 1997. print "tup1[0]: ". Accessing Values in Tuples: To access values in tuple. concatenated and so on. use compare func if given 9 Tuples A tuple is a sequence of immutable ( not changeable) Python objects. 2. even though there is only one value: Tup1 = (50. 'chemistry'. "c". Like string indices.). use the square brackets for slicing along with the index or indices to obtain value available at that index: Example: #!/usr/bin/python tup1 = ('physics'. The only difference is that tuples can't be changed i. just like lists.
But we able able to take portions of an existing tuples to create a new tuples as follows: Example: #!/usr/bin/python tup1 = (12. just use the del statement: Example: #!/usr/bin/python tup = ('physics'. tup2 = ('abc'. 'xyz'). 4. # Following action is not valid for tuples # tup1 += tup2. 34. nothing wrong with putting together another tuple with the undesired elements discarded. 2000).56). This will produce following result: (12. 'abc'.56. There is. del tup. # So let's create a new tuple as follows tup3 = tup1 + tup2.Game Scripting with Python – Tim Glasser This will produce following result: tup1[0]: physics tup2[1:5]: [2. To explicitly remove an entire tuple. print "After deleting tup : " 72 . print tup3. print tup. 34. 'xyz') Delete Tuple Elements: Removing individual tuple elements is not possible. 1997. 3. 'chemistry'. of course. 5] Updating Tuples: Tuples are immutable which means you cannot update them or change values of tuple elements.
NameError: name 'tup' is not defined Basic Tuples Operations: Tuples respond to the + and * operators much like strings. 3) + (4. 3. not a string. 2. 'SPAM!') Python Expression L[2] L[-2] 'SPAM!' 'Spam' Results Description Offsets start at zero Negative: count from the 73 . 3) for x in (1. they mean concatenation and repetition here too. Note an exception raised. Assuming following input: L = ('spam'. 5. tuples respond to all of the general sequence operations we used on strings in the prior chapter : Python Expression len((1. 3)) (1. line 9. 3 (1. except that the result is a new tuple. 6) ['Hi!'] * 4 3 in (1. 'Hi!'. 3): print x. 6) ('Hi!'. this is because after del tup tuple does not exist any more: ('physics'. in <module> print tup.py". 'Hi!'. 4. 2. 'Hi!') True 123 Results Length Concatenation Repetition Membership Iteration Description Indexing. 1997. 2000) After deleting tup : Traceback (most recent call last): File "test. and Matrixes: Because tuples are sequences.Game Scripting with Python – Tim Glasser print tup. This will produce following result. Slicing. indexing and slicing work the same way for tuples as they do for strings. 5. 'chemistry'. 'Spam'. 2. 2. In fact. 2.
as indicated in these short examples: #!/usr/bin/python print 'abc'. x. -4. default to tuples. ['Spam'. y = 1. 18+6. 'xyz'.e. y : 1 2 Built-in Tuple Functions: Python includes following tuple functions SN 1 2 3 4 5 Function with Description cmp(tuple1.6j. i. 'SPAM!'] Slicing fetches sections 74 . print var.24e+93 (18+6..y. min(tuple) Returns item from the tuple with min value. print "Value of x . x. parentheses for tuples. tuple(seq) Converts a list into tuple. comma-separated.6j) xyz Value of x .24e93. etc.. tuple2) Compares elements of both tuples. brackets for lists. len(tuple) Gives the total length of the tuple. 2. y : ". written without identifying symbols. This will reduce following result: abc -4.Game Scripting with Python – Tim Glasser right L[1:] No Enclosing Delimiters: Any set of multiple objects. max(tuple) Returns item from the tuple with max value.
like this: {}. dict['Age']. print "dict['Name']: ". but the keys must be of an immutable data type such as strings. dict['Name']. the items are separated by commas. and the whole thing is enclosed in curly braces.Game Scripting with Python – Tim Glasser Dictionaries A dictionary is mutable and is another container type that can store any number of Python objects. Dictionaries consist of pairs (called items) of keys and their corresponding values. 'Class': 'First'}. 'Beth': '9102'. 'Cecil': '3258'} You can create dictionary in the following way as well: dict1 = { 'abc': 456 }. 98. print "dict['Age']: ".6: 37 }. This will produce following result: 75 . Keys are unique within a dictionary while values may not be. including other container types. The general syntax of a dictionary is as follows: Dict = {'Alice': '2341'. Accessing Values in Dictionary: To access dictionary elements. 'Age': 7. The values of a dictionary can be of any type. you use the familiar square brackets along with the key to obtain its value: Example: #!/usr/bin/python dict = {'Name': 'Zara'. An empty dictionary without any items is written with just two curly braces. dict2 = { 'abc': 123. numbers. Python dictionaries are also known as associative arrays or hash tables. or tuples. Each key is separated from its value by a colon (:).
in <module> print "dict['Alice']: ".. dict['Alice']. This will produce following result: dict['Age']: 8 dict['School']: DPS School Delete Dictionary Elements: 76 . # Add new entry print "dict['Age']: ". dict['Alice']. 'Age': 7. KeyError: 'Alice' Updating Dictionary: You can update a dictionary by adding a new entry or item (i. 'Class': 'First'}. line 4.py". dict['Age'] = 8. a key-value pair). dict['School']. dict['Age']. modifying an existing entry.e. print "dict['School']: ". we get an error as follows: #!/usr/bin/python dict = {'Name': 'Zara'. or deleting an existing entry as shown below: Example: #!/usr/bin/python dict = {'Name': 'Zara'. 'Class': 'First'}.Game Scripting with Python – Tim Glasser dict['Name']: Zara dict['Age']: 7 If we attempt to access a data item with a key which is not part of the dictionary. print "dict['Alice']: ". # update existing entry dict['School'] = "DPS School". 'Age': 7. This will produce following result: dict['Zara']: Traceback (most recent call last): File "test.
the last assignment wins. same is not true for the keys. dict['School']. You can also delete entire dictionary in a single operation. This will produce following result. Properties of Dictionary Keys: Dictionary values have no restrictions. line 8.clear(). del dict['Name']. 'Class': 'First'}. When duplicate keys encountered during assignment. just use the del statement: Example: #!/usr/bin/python dict = {'Name': 'Zara'. # remove entry with key 'Name' dict. either standard objects or user-defined objects. print "dict['School']: ". Example: #!/usr/bin/python 77 . However. To explicitly remove an entire dictionary. Note an exception raised. There are two important points to remember about dictionary keys: (a) More than one entry per key not allowed. in <module> print "dict['Age']: ". Which means no duplicate key is allowed. this is because after del dict dictionary does not exist any more: dict['Age']: Traceback (most recent call last): File "test.Game Scripting with Python – Tim Glasser You can either remove individual dictionary elements or clear the entire contents of a dictionary.py". dict['Age']. # delete entire dictionary print "dict['Age']: ". # remove all entries in dict del dict . dict['Age']. TypeError: 'type' object is unsubscriptable Note: del() method is discussed in subsequent section. 'Age': 7. They can be any arbitrary Python object.
'Age': 7}. in <module> dict = {['Name']: 'Zara'. dict['Name']. Note an exception raised: Traceback (most recent call last): File "test. dict2) Compares elements of both dict. Which means you can use strings. This will produce following result: Dict['Name']: Manni (b) Keys must be immutable. This will produce following result. Example: #!/usr/bin/python dict = {['Name']: 'Zara'.Game Scripting with Python – Tim Glasser dict = {'Name': 'Zara'. This would be equal to the number of items in the dictionary. 'Age': 7}. If passed variable is dictionary then it would return a dictionary type. or tuples as dictionary keys but something like ['key'] is not allowed. line 3. len(dict) Gives the total length of the dictionary. TypeError: list objects are unhashable Built-in Dictionary Functions & Methods: Python includes following dictionary functions SN 1 Function with Description cmp(dict1. print "dict['Name']: ".py". str(dict) Produces a printable string representation of a dictionary type(variable) Returns the type of the passed variable. dict['Name']. numbers. 'Age': 7. 2 3 4 78 . print "dict['Name']: ". 'Name': 'Manni'}.
update(dict2) Adds dictionary dict2's key-values pairs to dict dict. dict.copy() Returns a shallow copy of dictionary dict dict. Add "John Smith" and "Mary Miller" at the beginning of the list (by using "+").values() Returns list of dictionary dict2's values Exercises 1) Create a list that contains the names of 5 students of this class.clear() Removes all elements of dictionary dict dict. Print the original list and the reverse list. Ask the user to input a name and return the appropriate phone number.get(key. Print the list. 3) Create a Dictionary of names and phone numbers. 2) Continue with the script from 1.Game Scripting with Python – Tim Glasser Python includes following dictionary methods SN 1 2 2 3 4 5 6 7 8 9 Methods with Description dict. simply create the list. default=None) For key key. Check whether that name is in the list: if it is then delete it from the list. Ask a user to input a number. 79 . (Do not ask for input to do that.keys() Returns list of dictionary dict's keys dict. but will set dict[key]=default if key is not already in dict dict.) Print the list.setdefault(key. returns value or default if key not in dictionary dict. Create a copy of the list in reverse order. Print the list. Print the list. Print the name that has that number as index. Ask a user to type a name. default=None) Similar to get(). false otherwise dict. Ask the user to input one more name and append it to the list.has_key(key) Returns true if key in dictionary dict. value) tuple pairs dict.fromkeys() Create a new dictionary with keys from seq and values set to value.1): Print the list.items() Returns a list of dict's (key. Remove the last name from the list. Otherwise add it at the end.
Game Scripting with Python – Tim Glasser Week 7 – Object Oriented Programming – Start Pygame Here Exercises: 1) Create a board and a counter class which have a visual draw method using Pygame 2) How should the board and counters be linked together? 3) Create a sprite with animation and gamepad comtrol 4) Create a background tile set 16*16 loading from a text file 5) Integrate the sprite and background 6) Add an enemy sprite 80 .
separated by commas. This function converts the expressions you pass it to a string and writes the result to standard output as follows: #!/usr/bin/python print "Python is really a great language.Game Scripting with Python – Tim Glasser Week 8 – Input and Output This chapter will cover all the basic I/O functions available in Python. str This would prompt you to enter any string and it would display same string on the screen. When I typed "Hello Python!".". which by default comes from the your keyboard. isn't it? Reading Keyboard Input: Python provides two built-in functions to read a line of text from standard input. print "Received input is : ". Printing to the Screen: The simplest way to produce output is using the print statement where you can pass zero or more expressions. it output is like this: Enter your input: Hello Python Received input is : Hello Python The input Function: 81 . This would produce following result on your standard screen: Python is really a great language. These functions are: raw_input input The raw_input Function: The raw_input([prompt]) function reads one line from standard input and returns it as a string (removing the trailing newline): #!/usr/bin/python str = raw_input("Enter your input: "). "isn't it?".
Game Scripting with Python – Tim Glasser The input([prompt]) function is equivalent to raw_input. access_mode: The access_mode determines the mode in which the file has to be opened ie. Here is a list of the different modes of opening a file: 82 . read. you have been reading and writing to the standard input and output. Syntax: file object = open(file_name [. This is optional parameter and the default file access mode is read (r) buffering: If the buffering value is set to 0. A complete list of possible values is given below in the table. The open Function: Before you can read or write a file. no buffering will take place. then buffering action will be performed with the indicated buffer size. except that it assumes the input is a valid Python expression and returns the evaluated result to you: #!/usr/bin/python str = raw_input("Enter your input: "). str This would produce following result against the entered input: Enter your input: [x*5 for x in range(2. If you specify the buffering value as an integer greater than 1. This function creates a file object which would be utilized to call other support methods associated with it. 30. You can do your most of the file manipulation using a file object. buffering]) Here is paramters detail: file_name: The file_name argument is a string value that contains the name of the file that you want to access.2)] Recieved input is : [10. access_mode][.10. 40] Opening and Closing Files: Until now. This is optional paramter. Now we will see how to play with actual data files. Python provides basic functions and methods necessary to manipulate files by default. 20. print "Received input is : ". write append etc. If the buffering value is 1. you have to open it using Python's built-in open() function. line buffering will be performed while accessing a file.
This is the default mode. The file pointer is at the end of the file if the file exists. creates a new file for reading and writing. Overwrites the existing file if the file exists. you can get various information related to that file. it creates a new file for writing. If the file does not exist. The file pointer is placed at the beginning of the file. Overwrites the existing file if the file exists. Opens a file for both appending and reading in binary format. Opens a file for appending. If the file does not exist. the file is in the append mode. The file pointer is placed at the beginning of the file. Here is a list of all attributes related to file object: 83 . the file is in the append mode. Opens a file for reading only in binary format. Opens a file for appending in binary format. it creates a new file for reading and writing.Game Scripting with Python – Tim Glasser Modes r rb r+ rb+ w wb w+ Description Opens a file for reading only. If the file does not exist. If the file does not exist. Opens a file for writing only in binary format. That is. The file opens in the append mode. If the file does not exist. The file opens in the append mode. If the file does not exist. The file pointer will be at the beginning of the file. Opens a file for both reading and writing in binary format. Opens a file for both appending and reading. Overwrites the file if the file exists. That is. creates a new file for writing. This is the default mode. The file pointer is at the end of the file if the file exists. wb+ a ab a+ ab+ The file object atrributes: Once a file is opened and you have one file object. The file pointer is at the end of the file if the file exists. creates a new file for writing. Opens a file for writing only. The file pointer is at the end of the file if the file exists. it creates a new file for writing. Opens a file for both reading and writing. Opens a file for both writing and reading. it creates a new file for reading and writing. The file pointer will be at the beginning of the file. If the file does not exist. If the file does not exist. Overwrites the file if the file exists. creates a new file for reading and writing. Opens a file for both writing and reading in binary format.
fo. fo. Python automatically closes a file when the reference object of a file is reassigned to another file. true otherwise.Game Scripting with Python – Tim Glasser Attribute file. "wb") print "Name of the file: ". 84 . fo. fo.txt". Returns false if space explicitly required with print.name print "Closed or not : ".mode print "Softspace flag : ".closed print "Opening mode : ". false otherwise.closed file. fo.name Description Returns true if file is closed. Returns name of the file. Syntax: fileObject. after which no more writing can be done.softspace Example: #!/usr/bin/python # Open a file fo = open("foo.txt".name file.softspace This would produce following result: Name of the file: foo. Example: #!/usr/bin/python # Open a file fo = open("foo. "wb") print "Name of the file: ".txt Closed or not : False Opening mode : wb Softspace flag : 0 The close() Method: The close() method of a file object flushes any unwritten information and closes the file object.mode file. It is a good practice to use the close() method to close a file.close(). Returns access mode with which file was opened.
The write() Method: The write() method writes any string to an open file.txt file and would write given content in that file and finally it would close that file.txt Reading and Writing Files: The file object provides a set of access methods to make our lives easier. The write() method does not add a newline character ('\n') to the end of the string: Syntax: fileObject. Yeah its great!! 85 .write(string). We would see how to use read() and write() methods to read and write files.close() This would produce following result: Name of the file: foo. If you would open this file.txt".\nYeah its great!!\n").Game Scripting with Python – Tim Glasser # Close opend file fo. "wb") fo. it would have following content Python is a great language.write( "Python is a great language. Here passed parameter is the content to be written into the opend file. # Close opend file fo. It is important to note that Python strings can have binary data and not just text. Example: #!/usr/bin/python # Open a file fo = open("foo.close() The above method would create foo.
"r+") str = fo. it means use the beginning of the file as the reference position and 1 means use the current position as the reference position and if it is set to 2 then the end of the file would be taken as the reference position. Here passed parameter is the number of bytes to be read from the opend file.txt".close() This would produce following result: Read String is : Python is File Positions: The tell() method tells you the current position within the file in other words.txt which we have created above. from]) method changes the current file position. print "Read String is : ". It is important to note that Python strings can have binary data and not just text. Example: Let's take a file foo. Example: 86 .read([count]).Game Scripting with Python – Tim Glasser The read() Method: The read() method read a string from an open file. The from argument specifies the reference position from where the bytes are to be moved. Syntax: fileObject. may be until the end of file. The offset argument indicates the number of bytes to be moved. str # Close opend file fo. This method starts reading from the beginning of the file and if count is missing then it tries to read as much as possible. the next read or write will occur at that many bytes from the beginning of the file: The seek(offset[.read(10). If from is set to 0. #!/usr/bin/python # Open a file fo = open("foo.
rename(current_file_name. str # Check current position position = fo. print "Again read String is : ".tell(). position # Reposition pointer at the beginning once again position = fo. The rename() Method: The rename() method takes two arguments.close() This would produce following result: Read String is : Python is Current file position : 10 Again read String is : Python is Renaming and Deleting Files: Python os module provides methods that help you perform file-processing operations. such as renaming and deleting files. the current filename and the new filename.Game Scripting with Python – Tim Glasser Let's take a file foo.txt: 87 .seek(0.read(10). str = fo. "r+") str = fo.txt which we have created above.read(10). 0). #!/usr/bin/python # Open a file fo = open("foo. new_file_name) Example: Following is the example to rename an existing file test1. Syntax: os. str # Close opend file fo. print "Current file position : ". print "Read String is : ". To use this module you need to import it first and then you can all any related functions.txt".
txt os.txt") Exercises: 1) Ask the user for a Python script file.txt: #!/usr/bin/python import os # Delete file test2. Syntax: os. 2) Create the 1-12 times tables and format the output in to a file named after the first argument to the script 88 .Game Scripting with Python – Tim Glasser #!/usr/bin/python import os # Rename a file from test1. open the file and report how many lines and how many words are in the file.txt" ) The delete() Method: You can use the delete() method to delete files by supplying the name of the file to be deleted as the argument.delete("text2.rename( "test1. Don’t forget to close the file.txt".txt to test2.delete(file_name) Example: Following is the example to delete an existing file test2. "test2.txt os.
import has the following syntax: import module1[. Asearch path is a list of directories that the interpreter searches before importing a module.. Simply. A module is a Python object with arbitrarily named attributes that you can bind and reference. a module is a file consisting of Python code.Game Scripting with Python – Tim Glasser Week 9 Modules A module allows you to logically organize your Python code.. par return The import Statement: You can use any Python source file as a module by executing an import statement in some other Python source file. module2[.py. classes. Grouping related code into a module makes the code easier to understand and use.print_func("Zara") 89 .py. Example: The Python code for a module named aname normally resides in a file named aname. hello. Example: To import the module hello. A module can define functions..py def print_func( par ): print "Hello : ". and variables. you need to put the following command at the top of the script: #!/usr/bin/python # Import module hello import hello # Now you can call defined function that module as follows hellp. moduleN] When the interpreter encounters an import statement. Here's an example of a simple module. it imports the module if the module is present in the search path.
Locating Modules: When you import a module. name2[..import Statement Python's from statement lets you import specific attributes from a module into the current namespace: Syntax: from modname import name1[. . this statement should be used sparingly.Game Scripting with Python – Tim Glasser This would produce following result: Hello : Zara A module is loaded only once. however.. The from. regardless of the number of times it is imported.. to import the function fibonacci from the module fib. The from.. the Python interpreter searches for the module in the following sequences: 90 . nameN]] Example: For example. use the following statement: from fib import fibonacci This statement does not import the entire module fib into the current namespace..import * Statement: It is also possible to import all names from a module into the current namespace by using the following import statement: from modname import * This provides an easy way to import all the items from a module into the current namespace. This prevents the module execution from happening over and over again if multiple imports occur.. it just introduces the item fibonacci from the module fib into the global symbol table of the importing module.
path variable. you must first use the global statement.Game Scripting with Python – Tim Glasser The current directory. Therefore. And here is a typical PYTHONPATH from a UNIX system: set PYTHONPATH=/usr/local/lib/python Namespaces and Scoping: Variables are names (identifiers) that map to objects. A Python statement can access variables in a local namespace and in the global namespace. Python checks the default path. PYTHONPATH. Each function has its own local namespace. If a local and a global variable have the same name. If the module isn't found. this default path is normally /usr/local/lib/python/. The PYTHONPATH Variable: The PYTHONPATH is an environment variable. and the installationdependent default. 91 . On UNIX. Python makes educated guesses on whether variables are local or global. Python stops searching the local namespace for the variable. It assumes that any variable assigned a value in a function is local. Python then searches each directory in the shell variable PYTHONPATH. The module search path is stored in the system module sys as the sys. A namespace is a dictionary of variable names (keys) and their corresponding objects (values).path variable contains the current directory. The syntax of PYTHONPATH is the same as that of the shell variable PATH. Class methods follow the same scoping rule as ordinary functions. Here is a typical PYTHONPATH from a Windows system: set PYTHONPATH=c:\python20\lib. consisting of a list of directories. The statement global VarName tells Python that VarName is a global variable. in order to assign a value to a global variable within a function. The sys. If all else fails. the local variable shadows the global variable.
'atan2'. 'sin'. 'radians'. 'pi'. 'hypot'. 'fmod'. therefor Python assumes Money is a local variable. so an UnboundLocalError is the result. 'modf'.Game Scripting with Python – Tim Glasser For example. 'atan'. we define a variable Money in the global namespace. 'log10'. 'ldexp'. 'floor'. 'tanh'] 92 . 'sqrt'. Example: #!/usr/bin/python # Import built-in module math import math content = dir(math) print content. 'frexp'. 'acos'. we access the value of the local variable Money before setting it. 'asin'. 'tan'. 'exp'. '__file__'. 'cosh'. Uncommenting the global statement fixes the problem. 'cos'. '__name__'. However. #!. 'pow'. 'log'. 'degrees'. The list contains the names of all the modules. we assign Money a value . 'e'. 'sinh'. 'ceil'. This would produce following result: ['__doc__'. Within the function Money. and functions that are defined in a module. 'fabs'. variables.
Game Scripting with Python – Tim Glasser Here the special string variable __name__ is the module's name. do the following: reload(hello) 93 . the code in the top-level portion of a module is executed only once. you can use the reload() function. The reload() Function: When the module is imported into a script. it will return all the names that can be accessed locally from that function. it will return all the names that can be accessed globally from that function. and __file__ is the filename from which the module was loaded. The reload() function imports a previously imported module again. If locals() is called from within a function. Therefore. Therefore. If globals() is called from within a function. names can be extracted using the keys() function. The return type of both these functions is dictionary. Syntax: The syntax of the reload() function is this: reload(module_name) Here module_name is the name of the module you want to reload and not the string containing the module name. For example to re-load hello module. The globals() and locals() Functions: The globals() and locals() functions can be used to return the names in the global and local namespaces depending on the location from where they are called. if you want to reexecute the top-level code in a module.
. Here are few important points above the above mentioned syntax: 94 .. then execute this block.....Game Scripting with Python – Tim Glasser Week 10 – Handling Errors Python provides two very important features to handle any unexpected error in your Python programs and to add debugging capabilities in them: Exception Handling: This would be covered in this tutorial.. . when a Python script encounters a situation that it can't cope with.else blocks: try: Do you operations here. followed by a block of code which handles the problem as elegantly as possible. Assertions: This would be covered in another tutorial. except ExceptionI: If there is ExceptionI.... In general. it must either handle the exception immediately otherwise it would terminate and come out...except... else: If there is no exception then execute this block... then execute this block. ... Handling an exception: If you have some suspicious code that may raise an exception.. Syntax: Here is simple syntax of try.. include an except: statement... What is Exception? An exception is an event. When a Python script raises an exception.. After the try: block......... which occurs during the execution of a program.... it raises an exception....... except ExceptionII: If there is ExceptionII...... An exception is a Python object that represents an error.. you can defend your program by placing the suspicious code in a try: block. which then disrupts the normal flow of the program's instructions..
This is useful when the try block contains statements that may throw different types of exceptions. "w") fh. The code in the elseblock executes if the code in the try: block does not raise an exception.Game Scripting with Python – Tim Glasser A single try statement can have multiple except statements. You can also provide a generic except clause. The else-block is a good place for code that does not need the try: block's protection. you can include an else-clause. which handles any exception.write("This is my test file for exception handling!!") except IOError: print "Error: can\'t find file or read data" else: print "Written content in the file successfully" fh.write("This is my test file for exception handling!!") except IOError: print "Error: can\'t find file or read data" else: print "Written content in the file successfully" This will produce following result: 95 . After the except clause(s). Example: Here is simple example which opens a file and writes the content in the file and comes out gracefully because there is no problem at all: #!/usr/bin/python try: fh = open("testfile".close() This will produce following result: Written content in the file successfully Example: Here is one more simple example which tries to open a file where you do not have permission to write in the file so it raises an exception: #!/usr/bin/python try: fh = open("testfile". "w") fh.
...... except(Exception1[.. though..... then execute this block....... ..... The except clause with multiple exceptions: You can also use the same except statement to handle multiple exceptions as follows: try: Do you operations here.. The finally block is a place to put any code that must execute.. . except: If there is any exception... This kind of a try-except statement catches all the exceptions that occur.Game Scripting with Python – Tim Glasser Error: can't find file or read data The except clause with no exceptions: You can also use the except statement with no exceptions defined as follows: try: Do you operations here... Exception2[.. else: If there is no exception then execute this block............. ...... Standard Exceptions: Here is a list standard Exceptions available in Python: Standard Exceptions The try-finally clause: You can use a finally: block along with a try: block. because it catches all exceptions but does not make the programmer identify the root cause of the problem that may occur.... . else: If there is no exception then execute this block..........ExceptionN]]]): If there is any exception from the given exception list... whether the try-block raised an exception or not................... then execute this block.......... The syntax of the try-finally statement is this: 96 .. Using this kind of try-except statement is not considered a good programming practice.
... the execution immediately passes to the finally block......... this may be skipped.. After all the statements in the finally block are executed.write("This is my test file for exception handling!!") finally: print "Error: can\'t find file or read data" If you do not have permission to open the file in writing mode then this will produce following result: Error: can't find file or read data Same example can be written more cleanly as follows: #!/usr/bin/python try: fh = open("testfile". the exception is raised again and is handled in the except statements if present in the next higher layer of the try-except statement.. Example: #!/usr/bin/python try: fh = open("testfile"... .. You can not use else clause as well along with a finally clause.. "w") fh. "w") try: fh.Game Scripting with Python – Tim Glasser try: Do you operations here..... or a finally clause.. 97 .... . but not both...... Note that you can provide except clause(s)......close() except IOError: print "Error: can\'t find file or read data" When an exception is thrown in the try block...write("This is my test file for exception handling!!") finally: fh... finally: This would always be executed.. Due to any exception...
py. Artificial intelligence (or AI) is a computer program that can intelligently respond to the player's moves. We will see that the artificial intelligence that plays Tic Tac Toe is really just several lines of code. Then run the game by pressing F5. | | O | | | | ----------| | | | | | ----------| | | | | | What is your next move? (1-9) 3 | | O | | | | ----------| | | | | | ----------| | O | | X | | What is your next move? (1-9) 4 | | O | | O | | ----------| | X | | 98 . type in this source code and save it as tictactoe.Game Scripting with Python – Tim Glasser Appendix A – Designing and Implementing a Tic Tac Toe Game We will now create a Tic Tac Toe game where the player plays against a simple artificial intelligence. So in a new file editor window. Sample Run Welcome to Tic Tac Toe! Do you want to be X or O? X The computer will go first. This game doesn't introduce any complicated new concepts.
randomly choose who goes first. Here is what a flow chart of this game could look like: 99 . Do you want to play again? (yes or no) no Designing the Program Tic Tac Toe is a very easy and short game to play on paper. and then let the player and computer take turns making moves on the board. we'll let the player choose if they want to be X or O. In our Tic Tac Toe computer game.Game Scripting with Python – Tim Glasser | | ----------| | O | | X | | What is your next move? (1-9) 5 | | O | O | O | | ----------| | X | X | | | ----------| | O | | X | | The computer has beaten you! You lose.
O. The player has an extra box for drawing the board because the computer doesn't need the board printed on the screen. First. The ten strings will represent each of the nine positions on the board (and we will ignore one of our strings). 'O' for the O player.Game Scripting with Python – Tim Glasser You can see a lot of the boxes on the left side of the chart are what happens during the player's turn. we ask the player if they want to play again. The strings will either be 'X' for the X player. or blank space). board[5] would be the very 100 . If either the computer or player ties or wins the game. we check if they won or caused a tie. and then the game switches turns. or a space string ' ' to mark a spot on the board where no one has marked yet. we will mirror the numbers on the keypad of our keyboard. we will just ignore the string at index 0 in our list. The right side of the chart shows what happens on the computer's turn. After the player or computer makes a move.) So if we had a list with ten strings named board. To make it easier to remember which index in the list is for which piece. then board[7] would be the topleft square on the board (either an X. (Because there is no 0 on the keypad. we need to figure out how we are going to represent the board as a variable. We are going to represent the Tic Tac Toe board as a list of ten strings.
go to step 3. If there is. # Tic Tac Toe 2. 5. 2. see if there is a move the computer can make that will win the game. 3. 101 . or 9) are free. 3. An algorithm is a series of instructions to compute something. import random A comment and importing the random module so we can use the randint() function in our game. we should move there to block the player. First. because if we have reached step 5 the side spaces are the only spaces left.Game Scripting with Python – Tim Glasser center. we will label three types of spaces on the Tic Tac Toe board: corners. sides. If so. Here is a chart of what each space is: The AI for this game will follow a simple algorithm. go to step 2. take that move. Our algorithm will have the following steps: 1. Otherwise. There are no more steps. then go to step 4. If there is. 6. Otherwise. Check if the center is free. and the center. (We always want to take a corner piece instead of the center or a side piece. See if there is a move the player can make that will cause the computer to lose the game.) If no corner piece is free. then go to step 5. move there. 4. 7. Our Tic Tac Toe AI's algorithm will determine which is the best place to move. Game AI Just to be clear. Source Code 1. When the player types in which place they want to move. 3. 4. they will type a number from 1 to 9. Move on any of the side pieces (spaces 2. Check if any of the corner spaces (spaces 1. or 8). If it isn't.
Just as an example. ' '. print ' | |' 16. 'X'. print ' ' + board[4] + ' | ' + board[5] + ' | ' + board[6] 15. 'X'. print ' | |' 18. ' '. ' '. 'O'. def drawBoard(board): 6. otherwise the board will look funny when it is printed on the screen. ' '. # "board" is a list of 10 strings representing the board (ignore index 0) 9. print ' | |' 12. ' '. ' '. 8. print ' | |' 10.Game Scripting with Python – Tim Glasser 5. ' '. print '-----------' 13. here are some values that the board parameter could have (on the left) and what the drawBoard() function would print out: drawBoard(board) output | | X | | O | | ----------| | X | O | | | ----------| | | | | | | | | | | | ----------| | | X | board data structure [' '. print ' ' + board[1] + ' | ' + board[2] + ' | ' + board[3] 19. ' '] 102 . 'X'. 'O'. 7. print ' ' + board[7] + ' | ' + board[8] + ' | ' + board[9] 11. ' '. Be sure to get the spacing right in the strings that are printed. 'O'] [' '. print ' | |' This function will print out the game board. print '-----------' 17. # This function prints out the board that it was passed. ' '. print ' | |' 14. ' '. Many of our functions will work by passing the board as a list of ten strings to our functions. marked as directed by the board parameter. 'O'.
'X'. 'X'] Copyright 2008. 'X'. ' '] [' '. ' '. 'X'. 'X'. 'X'. 'X'. ' '. ' '.Game Scripting with Python – Tim Glasser | | ----------| | O | O | | | | | | | | | ----------| | | | | | ----------| | | | | | | | X | X | X | | ----------| | X | X | X | | ----------| | X | X | X | | [' '. ' '. 'X'. 2009 © by Albert Sweigart "Invent Your Own Computer Games with Python" is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3. ' '. ' '. ' '. 103 . ' '.0 United States License. 'X'.
current pedal cadence. Each discussion focuses on how these concepts relate to the real world. off. but your desktop radio might have additional states (on. breed. Software objects are often used to model the real-world objects that you find in everyday life. Look around right now and you'll find many examples of real-world objects: your dog.Game Scripting with Python – Tim Glasser Appendix B Object Oriented Programming Objectives • Understand the basic Object Oriented principles. turn off). in turn. your desk. your desktop lamp may have only two possible states (on and off) and two possible behaviors (turn on. What Is an Object? Objects are key to understanding object-oriented technology. decrease volume. This lesson explains how state and behavior are represented within an object. For each object that you see. introduces the concept of data encapsulation. ask yourself two questions: "What possible states can this object be in?" and "What possible behavior can this object perform?". As you do. 104 . scan. Make sure to write down your observations. changing pedal cadence. you will need to learn a few basic concepts before you can begin writing any code. hungry) and behavior (barking. fetching. applying brakes). and interfaces. and explains the benefits of designing your software in this manner. This lesson will introduce you to objects. and tune). which is composed of: • Understanding the idea of a component • Understanding Objects • Understanding Classes • Understandinding Inheritance • Understanding the Interface and Encapsulation Object-Oriented Programming Concepts If you've never used an object-oriented programming language before. current volume. wagging tail). you'll notice that real-world objects vary in complexity. color. classes. seek. turn off. inheritance. Real-world objects share two characteristics: They all have state and behavior. What Is an Object? An object is a software bundle of related state and behavior. Take a minute right now to observe the real-world objects that are in your immediate area. You may also notice that some objects. increase volume. Bicycles also have state (current gear. while simultaneously providing an introduction to the syntax of the C++ programming language. Dogs have state (name. your bicycle. Identifying the state and behavior for real-world objects is a great way to begin thinking in terms of objectoriented programming. current speed) and behavior (changing gear. your television set. current station) and behavior (turn on.
These real-world observations all translate into the world of object-oriented programming. the object remains in control of how the outside world is allowed to use it. and current gear) and providing methods for changing that state. An object stores its state in fields (variables in some programming languages) and exposes its behavior through methods (functions in some programming languages). a method to change gears could reject any value that is less than 1 or greater than 6. Software objects are conceptually similar to real-world objects: they too consist of state and related behavior. current pedal cadence. if the bicycle only has 6 gears. Consider a bicycle. 105 . A software object.Game Scripting with Python – Tim Glasser will also contain other objects. By attributing state (current speed. for example: A bicycle modeled as a software object. For example. Hiding internal state and requiring all interaction to be performed through an object's methods is known as data encapsulation — a fundamental principle of object-oriented programming. Methods operate on an object's internal state and serve as the primary mechanism for object-to-object communication.
This section defines a class that models the state and behavior of a real-world object. you replace it. Each bicycle was built from the same set of blueprints and therefore contains the same components. } void speedUp(int increment) { speed = speed + increment. Information-hiding: By interacting only with an object's methods. In the real world. The following Bicycle class is one possible implementation of a bicycle: class Bicycle { int cadence = 0. the details of its internal implementation remain hidden from the outside world. including: 1. int speed = 0. If a bolt breaks. } void changeGear(int newValue) { gear = newValue. you can use that object in your program. There may be thousands of other bicycles in existence. showing how even simple classes can cleanly model state and behavior. Debugging ease: If a particular object turns out to be problematic. This is analogous to fixing mechanical problems in the real world. you can simply remove it from your application and plug in a different object as its replacement. int gear = 1. 3. Once created. A class is the blueprint from which individual objects are created. task-specific objects. Code re-use: If an object already exists (perhaps written by another software developer). This allows specialists to implement/test/debug complex. void changeCadence(int newValue) { cadence = newValue. we say that your bicycle is an instance of the class of objects known as bicycles. Modularity: The source code for an object can be written and maintained independently of the source code for other objects. 4. } 106 . not the entire machine. What Is a Class? A class is a blueprint or prototype from which objects are created. 2. which you can then trust to run in your own code.Game Scripting with Python – Tim Glasser Bundling code into individual software objects provides a number of benefits. It intentionally focuses on the basics. In object-oriented terms. an object can be easily passed around inside the system. you'll often find many individual objects all of the same kind. all of the same make and model.
} } The design of this class is based on the previous discussion of bicycle objects. bike2.changeCadence(50).changeCadence(50). changeGear.changeGear(3).speedUp(10).speedUp(10). bike1. and the methods (changeCadence. speedUp etc.out.changeGear(2). } void printStates() { System. The responsibility of creating and using new Bicycle objects belongs to some other class in your application. speed. Bicycle bike2 = new Bicycle(). This section explains how classes inherit state and behavior from their 107 .changeGear(2). bike2. bike1. bike2.printStates(). bike2. bike1. bike2. } The output of this test prints the ending pedal cadence. Here's a BicycleDemo class that creates two separate Bicycle objects and invokes their methods: void main(String[] args) { // Create two different Bicycle objects Bicycle bike1 = new Bicycle(). it's just the blueprint for bicycles that might be used in an application. speed.printStates().decrement.changeCadence(40). That's because it's not a complete application.Game Scripting with Python – Tim Glasser void applyBrakes(int decrement) { speed = speed . You may have noticed that the Bicycle class does not contain a main method. and gear represent the object's state.) define its interaction with the outside world. bike2.speedUp(10).println("cadence:"+cadence+" speed:"+speed+" gear:"+gear). bike2. and gear for the two bicycles: cadence:50 speed:10 gear:2 cadence:40 speed:20 gear:3 Inheritance Inheritance provides a powerful and natural mechanism for organizing and structuring your software. // Invoke methods on those objects bike1. The fields cadence.
each class is allowed to have one direct superclass. followed by the name of the class to inherit from: class MountainBike :public Bicycle { // new fields and methods defining a mountain bike would go here } This gives MountainBike all the same fields and methods as Bicycle. current pedal cadence. What Is Inheritance? Different kinds of objects often have a certain amount in common with each other. and tandem bikes. road bikes. and TandemBike.Game Scripting with Python – Tim Glasser superclasses. road bikes have drop handlebars. In this example. This makes code for your 108 . At the beginning of your class declaration. and explains how to derive one class from another using the simple syntax provided by the C++ programming language. yet allows its code to focus exclusively on the features that make it unique. In the Java programming language. all share the characteristics of bicycles (current speed. The syntax for creating a subclass is simple. Bicycle now becomes the superclass of MountainBike. Object-oriented programming allows classes to inherit commonly used state and behavior from other classes. and each superclass has the potential for an unlimited number of subclasses: A hierarchy of bicycle classes. Mountain bikes. giving them a lower gear ratio. RoadBike. Yet each also defines additional features that make them different: tandem bicycles have two seats and two sets of handlebars. use the extends keyword. for example. some mountain bikes have an additional chain ring. current gear).
for example). for example. Methods form the object's interface with the outside world. You press the "power" button to turn the television on and off. When a class implements an interface. since that code will not appear in the source file of each subclass. void changeGear(int newValue){}. If your class claims to implement an interface. might appear as follows: class IBicycle { void changeCadence(int newValue){}. it promises to provide the behavior published by that interface. As you've already learned. the name of your class would change (to ACMEBicycle. } Note that this is an abstract class. objects define their interaction with the outside world through the methods that they expose. if specified as an interface. 109 . A bicycle's behavior. the buttons on the front of your television set. void applyBrakes(int decrement){}. are the interface between you and the electrical wiring on the other side of its plastic casing. all methods defined by that interface must appear in its source code before the class will successfully compile.Game Scripting with Python – Tim Glasser subclasses easy to read. Interfaces form a contract between the class and the outside world. Why? To implement this interface. you must take care to properly document the state and behavior that each superclass defines. In its most common form. and this contract is enforced at build time by the compiler. This section defines a simple interface and explains the necessary changes for any class that implements it. void speedUp(int increment){}. What Is an Interface? An interface is a contract between a class and the outside world. an interface is a group of related methods with empty bodies. and you'd use the implements keyword in the class declaration: class ACMEBicycle: public IBicycle { // remainder of this class implemented as before } Implementing an interface allows a class to become more formal about the behavior it promises to provide. However.
(This is Pygame for Python 2. download and install the newer Pygame. If you see a newer version on the website. You do not want to download the "source" for Pygame. In a web browser. sound.6 on Windows. all of our games have only used text. This book assumes you have the Windows operating system.1.) The current version of Pygame at the time this book was written is 1.Game Scripting with Python – Tim Glasser Appendix C . But in this chapter. but included in other programs to add new features. If you installed a different version of Python (such as 2. Text is displayed on the screen as output. we will make some more exciting games with advanced graphics and sound using the Pygame library.1. follow the directions on the download page for installation instructions. but Pygame works the same for every operating system. and other features that games commonly use. You will have to download and install Pygame. but rather the Pygame for your operating system. go to the URL and click on the Downloads link on the left side of the web site. A software library is code that is not meant to be run by itself.5 or 2.Graphics and Animation with Pygame So far. and the player types in text from the keyboard as input.4) download the . You need to download the Pygame installer for your operating system and your version of Python. Pygame is a software library for graphics. 110 . Like Python.msi file.8. By using a library a programmer doesn't have to write the entire program.6. Pygame is available for free.win32-py2. but can make use of the work that another programmer has done before them.msi file for your version of Python. This is simple. download the pygame-1. which is as easy as downloading and installing the Python interpreter. and an easy way to learn programming. For Mac OS X and Linux. For Windows.
font rendering) and sound devices (effects and music). then you know Pygame has successfully been installed. This chapter has five small programs that demonstrate how to use the different features that Pygame provides. then try to install Pygame again (and make sure you typed import pygame correctly). FULLSCREEN) Call set_mode to switch from windowed (the default) to fullscreen mode. 768). other people have done a really excellent job of providing Python libraries for user input and game output.Game Scripting with Python – Tim Glasser On Windows. The key to designing interesting games is to do something different or new. Fortunately. If you are using DOUBLEBUF. image blitting.display. pygame.flip() Drawing an Image 111 . type the following into the interactive shell: >>> import pygame I f nothing appears after you hit the Enter key. keyboard. Creating and Managing the Screen from pygame. PyGame provides user input handling (mouse. Python is possibly the simplest language for writing game simulations in. easy to learn. handles a lot of programming housekeeping and is reasonably fast.display. then you need to flip the screen after you've rendered it. If the error ImportError: No module named pygame appears.set_mode((1024. Games consist largely of user input.locals import * screen = pygame. double click on the downloaded file to install Pygame.set_mode((1024. joystick) and game output via the screen (shape drawing. It's clear to read and write. game output and some sort of world simulation. In the last chapter. Python is a really nice language for writing game simulations in. To check that Pygame is install correctly. 768)) screen = pygame. Other display mode flags (you just | them together): DOUBLEBUF should be used for smooth animation. you will use these features for a complete game written in Python with Pygame.display.
display.load('car. (50. Sprites. 0)) screen.pi / 180) screen. the BLIT (Block Image Transfer). the most common of which are: import pygame pygame.rotate(car. mentioned later. Images can also be rotated: import math car = pygame. (50.poll() pygame.Game Scripting with Python – Tim Glasser To draw an image on screen we use one of the most important drawing primitives. 0. help us do this.load('car. This copies an image from one place (eg. 45 * math.transform. It's usually better to update the parts of the screen that have changed instead. Input handling There are a number of ways to get user events in PyGame. the screen at x = 50.g.image. We always start counting x coordinates from the left.flip() The car should appear on the screen with its top left corner positioned at (50. and y coordinates from the top of the screen.get() 112 . 100). your source image) to another place (e.fill((0.event.image.event.blit(car. 100)) pygame.png') screen.png') rotated = pygame. 0)) Clearing and redrawing a screen is quite a slow technique of animating. 100)) pygame.event.flip() Animating the Image Animating anything on screen involves drawing a scene. y = 100).display.blit(car.wait() pygame. (i. clearing it and drawing it again slightly differently: for i in range(100): screen.blit(car. car = pygame.
Clock() FRAMES_PER_SECOND = 30 deltat = clock. This effectively limits the number of calls to tick to 30 per second. it returns NOEVENT and you can do other things. If there are no events.image. Bringing together some elements The following code will animate our little car according to user controls.load('car.png') clock = pygame.Game Scripting with Python – Tim Glasser Wait will sit and block further game execution until an event comes along. your game will run as fast as it possibly can on whatever platform it happens to be on. 768)) car = pygame.30 times a second is a reasonable number to aim for If a game is action oriented. Timing control is easy to add: clock = pygame. you may wish to aim for double that so that players feel their input is being processed in a super responsive manner. animation and rendering): # INTIALISATION import pygame. The actual time between tick calls is returned (in milliseconds) – on slower computers you might not be achieving 30 ticks per second.) Timing Without timing control. user input. Poll will see whether there are any events waiting for processing. as you animation needs to happen simultaneously. Note that the 30 frames per second will also determine how often your game responds to user input. sys from pygame.Clock() k_up = k_down = k_left = k_right = 0 speed = direction = 0 position = (100. Get. math.tick(FRAMES_PER_SECOND) tick instructs the clock object to pause until 1/30th of a second has passed since the last call to tick.set_mode((1024.locals import * screen = pygame. is like poll except that it returns all of the currently outstanding events (you may also filter the events it returns to be only key presses. It consists broadly of four sections (initialization. or mouse moves. Checking for user input any slower than 30 frames per second will result in noticeable delays for the user.display. as that is checked at the same time that the screen is drawn. This is not generally very useful for games. 100) TURN_SPEED = 5 113 .time.time. etc.
key == K_DOWN: k_down = down elif event. To do this. rect) pygame.transform.get_rect() rect. y) # RENDERING # . A sprite holds an image (e. we can use sprites. a car) and information about where that image should be drawn on screen (i. rotate the car image for direction rotated = pygame.type == KEYDOWN # key down if event. new position based on current position.key == K_ESCAPE: sys. direction) # .g.) This information is stored on the sprite's 114 . position the car on screen rect = rotated.exit(0) screen.event..flip() More structure Most designs will need better control simulation and rendering.key == K_UP: k_up = down * 2 elif event.blit(rotated.0.e.rotate(car.key == K_LEFT: k_left = down elif event.center = position # .. render the car to screen screen.sin(rad) y += speed* math.0) # GAME LOOP while 1: # USER INPUT clock.fill(BLACK) or up? * 5 * 5 * 2 # quit the game # SIMULATION # ..Game Scripting with Python – Tim Glasser ACCELERATION = 2 MAX_FORWARD_SPEED = 10 MAX_REVERSE_SPEED = 5 BLACK = (0.pi / 180 x += speed* math.display.key == K_RIGHT: k_right = down elif event.. new speed and direction based on acceleration and turn speed += (k_up + k_down) if speed > MAX_FORWARD_SPEED: speed = MAX_FORWARD_SPEED if speed < MAX_REVERSE_SPEED: speed = MAX_REVERSE_SPEED direction += (k_right + k_left) # .. speed and direction x.get(): if not hasattr(event. y = position rad = direction * math.cos(rad) position = (x. 'key'): continue down = event. its position.tick(30) for event in pygame.
y = self. self.Clock() class CarSprite(pygame.display.k_down) if self.locals import * screen = pygame. Sprite groups have a draw method which draws the group's sprites onto a supplied surface.position = (x.MAX_FORWARD_SPEED if self.MAX_FORWARD_SPEED: self.sprite.image.rotate(self.k_left = self.get_rect() self.Sprite): MAX_FORWARD_SPEED = 10 MAX_REVERSE_SPEED = 10 ACCELERATION = 2 TURN_SPEED = 5 def __init__(self.rect = self.speed > self.k_up = 0 def update(self. speed*math. They also have a clear method which can remove their sprites from the surface.direction * math.speed = self.set_mode((1024.speed = self.direction) self.cos(rad) self. deltat): # SIMULATION self.direction = 0 self.sin(rad) y += self.position = position self. speed*math.k_up + self. 768)) clock = pygame. sys from pygame.src_image = pygame.speed < self.center = self.load(image) self.src_image.Game Scripting with Python – Tim Glasser image and rectangle(rect) attributes.k_left) x.speed += (self.Sprite.sprite.transform. MAX_REVERSE_SPEED: self.image = pygame. Sprites are always dealt with in groups .time.k_right = self.__init__(self) self. position): pygame.position 115 .position rad = self. MAX_REVERSE_SPEED self. y) self. math.k_down = self.speed = self.pi / 180 x += self.k_right + self. image.image.rect. The above code rewritten using a sprite: # INTIALISATION import pygame.direction += (self.even if a group only has one Sprite.
RenderPlain(car) while 1: # USER INPUT deltat = clock. 'key'): continue down = event. The benefit of sprites really comes when you have a lot of images to draw on screen.tick(30) for event in pygame.image = self.image.update(deltat) car_group.k_down = down * 2 elif event.key == K_UP: car. rect.hit else: self.type == KEYDOWN if event.0)) car_group.load('pad_hit.png') hit = pygame.png') def __init__(self.display. hit_list): if self in hit_list: self.0.exit(0) # RENDERING screen.Game Scripting with Python – Tim Glasser # CREATE A CAR AND RUN rect = screen.draw(screen) pygame.sprite.key == K_RIGHT: car.png'.fill((0.normal pads = [ 116 .k_left = down * 5 elif event.k_right = down * 5 elif event.rect.flip() Mostly the code has just been moved around a little.Sprite): normal = pygame.sprite.key == K_ESCAPE: sys.Rect(self.get(): if not hasattr(event.image. position): self.center = position def update(self.key == K_DOWN: car. Checking for collisions is really pretty easy.k_up = down * 2 elif event.event.center) car_group = pygame.normal.key == K_LEFT: car.rect = pygame.load('pad_normal.get_rect() car = CarSprite('car.get_rect()) self. Let's put some pads to drive over into the simulation: class PadSprite(pygame.image = self. PyGame sprites have additional functionality that help us determine collisions.
center = position self.update(collisions) pad_group.get_rect()) self. 200)). We'll keep information indicating which order the pads must be visited: class PadSprite(pygame.sprite. PadSprite((200. PadSprite(2.spritecollide(car. pad_group) pad_group. just before we draw the car.load('pad_normal.Rect(self.draw(screen) So now we have a car. position): pygame. PadSprite(4. we check to see whether the car sprite is colliding with any of the pads.rect. number.load('pad_hit. PadSprite((800. (800. ] pad_group = pygame. (800.rect = pygame. 200)). 200)). (200. ] current_pad_number = 0 Now we replace the pad collision from above with code that makes sure we hit them in the correct order: pads = pygame. and pass that information to pad.png') def __init__(self. 600)).__init__(self) self.Sprite): normal = pygame. PadSprite(3.number = number self. controlled by the player and we can detect when the car hits other things on the screen. 200)).RenderPlain(*pads) now at the animation point.Sprite.sprite.Game Scripting with Python – Tim Glasser PadSprite((200. False) if pads: pad = pads[0] 117 . running around on the screen.image. 600)). 600)).sprite. (200.png') hit = pygame.spritecollide(car_group. PadSprite((800.normal pads = [ PadSprite(1.image = self.image.sprite. pad_group.update() so each pad knows whether to draw itself “hit” or not: collisions = pygame. Adding objectives It would be great if we could determine whether the car has made a "lap" of the "circuit" we've constructed.normal.sprite. 600)).
118 . and a good rule of thumb is to not optimize unless you really need to.image.number == current_pad_number + 1: pad. background) Now we are only ever updating the small areas of screen that we need to update.png') screen.blit(self.0)) Now inside the loop. but before we update and move the car. This is quite slow (though you might not notice) and is easily improved upon.blit(self.hit current_pad_number += 1 elif current_pad_number == 4: for pad in pad_group.background.clear(screen. (0.png') screen.Game Scripting with Python – Tim Glasser if pad. resetting the current_pad_number is where we'd flag that the player has run a lap.load('track. A further optimization would be to recognize that the pads only get updated very infrequently. and not draw / clear them each frame unless their state actually changes. We do this with the pads too: background = pygame.clear(screen.image = pad. background) car_group.fill((0. it just unnecessarily complicates your code. (0.background.0))).0. This optimization is not necessary just yet. we ask the car's sprite to clear itself from the screen.sprites(): pad.0)) pad_group.load('track. Adding a background Currently we are clearing the screen on every frame before rendering (screen.image = pad. Firstly outside the animation loop we load up a background image and draw it to the screen: background = pygame.normal current_pad_number = 0 The last part of that text.image. | https://www.scribd.com/document/72114845/TGlasser-IntroToPython | CC-MAIN-2017-47 | refinedweb | 24,915 | 68.47 |
Autocrop, despeckle, deskew image
Budjetti $30-250 USD
This is a simple imaging processing project. You must understand the Autocrop function found in a lot of scanners software, else you won't understand this requirement.
As the title suggest; a function needs to be made which will take a scanned image; autocrop any extra area around the image (image could be in bw,gray,color),despeckle, & adjust angle of the image (deskew). For the deskew part, there is already a class (DocumentSkewChecker, [url removed, login to view] namespace) in the [url removed, login to view] open source framework.
We expect it to be developed in .NET. We will supply scanned images of different shape, color & resolution. We may be open to using a open-source but you must tell us before using any and can not use any SDK or propitiatory stuff. We will have exclusive right to the developed program. We'd like to have this by this weekend. We must be able to test the function, which could be in a form etc. before the final acceptance.
Budget - US $100. Apply only if you did a similar job.
6 freelanceria on tarjonnut keskimäärin 143 $ tähän työhön
hi i am in image processing expert Please check the PM | https://www.fi.freelancer.com/projects/visual-basic-net/autocrop-despeckle-deskew-image/ | CC-MAIN-2018-05 | refinedweb | 209 | 73.78 |
MCP3903 Library
MCP3903 is a six channel Delta-Sigma A/D converter. It.
I have created a library for Arduino. It allows you to explore most of the functionalities MCP3903 provides with ease. The library can be downloaded towards the end of this post as usual. And it is also available on GitHub.
MCP3903 communicates with MCU over SPI and for the most part, the communication is pretty straight forward. Unlike many SPI devices for which the sending and receiving of the data happen simultaneously during an SPI.transfer call, sending and receiving data are done in MCP3903 via different commands. In its simplest terms (which covers most of the scenario), the communication (either sending or receiving) packet includes four bytes. The first byte is the control byte, which contains the device address, the register needs to be accessed and whether this command is a read or write. The subsequent three bytes are either read from or send to MCP3903 depending on whether the command is a read or write.
This fixed-width command structure makes programming very easy. For different ADC resolutions (e.g. 16 bit versus 24 bit) the command and data structures are identical. The ADC result would always contain 24 bits, the lower bits are simply filled with zeros when the resolution used is less than 24 bits. Again, this makes programming a lot simpler as we can treat all conversion results as 24 bits regardless of the resolution used.
Of course, when using some special features (e.g. continuous read), the command structure is slightly different than what we have mentioned above, but you can always add in these functions if you want to use them. But 90% of the time the functionalities provided in this library should be sufficient.
There are a couple of things you will need to pay attention to when using MCP3903. First, voltages applied at each differential pairs are limited to ±0.5V (when using a gain of one). While each of the analog inputs can handle up to ±6V without suffering any damage, the measurement results will not be accurate when the voltages fall outside of the linearity range. Second, MCP3903 has a gain of 3 amplifier on each channel, which is independent of the programmable gain settings. If you take a look at the implementation of the library function readADC, you will notice that the result has been scaled down by a factor of 3 to reflect the original measurement value.
Below are a few most used functions. For the full implementation, please refer to the source code linked towards the end of this post.
reset
This function resets MCP3903 to 24 bit operation mode (when no parameter is supplied), or you may specify a predefined OSR (over sampling ratio) factor for the desired bit resolution. Note that the reset does not change other register settings except for the gain setting mentioned earlier. According to the datasheet, a full reset can only be achieved via the RESET pin (pin 27).
setGain
This function changes the gain setting for the given channel. It can take either two parameters or three parameters. When two parameters are supplied, the first parameter is the channel number (0-5), and the second parameter is the desired gain (GAIN_1, GAIN_2, GAIN_4, GAIN_8, GAIN_16, GAIN_32 and GAIN_64). When a third parameter is supplied, the last parameter indicates whether to turn on current boost mode for the channel (1 to turn on boost).
readADC
Returns normalized ([-1,1]) ADC data for the supplied channel. Multiply this result by the reference voltage will yield the measured voltage. Because the value for the internal high stability (5ppm/°C) voltage reference can vary up to ±2%, you will want to measure the reference output with a high precision meter to obtain the reference voltage for your particular ADC first rather than relying on the nominal value to achieve the most accurate result. The nominal value for the internal voltage reference is 2.35V (in my example below, the actual reference voltage is 2.36V).
The following code shows how to read channel 1 results with 24 bit resolution and use a gain of 8. As mentioned earlier, the OSR_256 parameter can be omitted in this case as it is equivalent to the default reset with no parameter.
#include "MCP3903.h" #include <SPI.h> MCP3903 mcp3903; void setup() { SPI.begin(); Serial.begin(9600); mcp3903.reset(MCP3903::OSR_256); mcp3903.setGain(1,MCP3903::GAIN_8); } void loop() { Serial.println(mcp3903.readADC(1) * 2.36 , 4); delay(100); }
A few features are left out from this library (e.g. phase delay compensation between each pair of channels, pre-scaler settings, continuous read, etc.), but those who are interested can consult the datasheet and add in easily. The schematic below is the recommended design using internal voltage reference, note that the supply voltage for the digital portion of the circuitry is different from the analog portion. According to the datasheet, AVdd should be between 4.5V and 5.5V and DVdd should be between 2.7V and 3.6V.
Here is a picture of my test setup. In the picture below, a small differential voltage is applied to channel 0 via a resistor bridge.
Hi, first of all great job making the library!
I’m planning to use the MCP3903 with Arduino UNO and the library will be a great help!
Just a few questions: In the circuit you connect the 4MHz oscillator to OSC1 and OSC2, what are the values of the C4 and C5 caps? It seems like 33uF but I’m not sure
And I can’t see very clear the part of the board with transistor and caps, connected to pins 27 / 28, what are these for? Are you making the 3.3V from 5V?
Thanks in advance!
Hi Sergio,
C4 and C5 are load capacitors, in my circuit they are both 33pF. In general their value depends on the crystal you use, but typical values range from 20 to 60 pFs.
That isn’t a transistor, it’s a 3.3V voltage regulator.
Great!
I was planning to use the Arduino built-in 3.3V for DVDD, but maybe would be more elegant to use a regulator.
As soon as my chip comes I will start playing XD
Thank you!
I followed your schematic, but I keep getting zeros from the ADC. Did a similar problem occur for you?
(The readADC()-Method returns 0.00).
Thanks in advance!
I don’t recall running into this particular problem. Assuming you are reading from the correct channel, the only thing I’d double check is to make sure that the oscillator is working on MCP3903. and the MOSI pins are connected correctly (in this case you need to use pin 10 as CS).
I’m really stuck. Actually, I rewrote the entire SPI library (in order to add some delays, needed for my crappy scope to catch the bits) – but although the Arduino sends everything correctly, monitoring the SDO output shows exactly the same signal as on SDI (apart from some strange noise). I tried every register (Channels + Config registers). I tried it both with Arduino Due (3.3V logic) and Arduino Micro (5V logic).
This behavior doesn’t even change when I remove power supply from the Chip.
Anyone who can help me? Thanks a lot!
I am having the same problem (getting 0.00). I also tried mcp3903 on Raspberry pi using my own program but still I got 0.00.
Is there any solution to this problem?
Is there any library for interfacing MCP3903 with Raspberry pi ?
Is the 4 mHz oscillator required, or does the MCP3903 have an internal oscillator?
MCP3903 does not have an internal clock, so you must either use a crystal (setting CLKEXT = 0) or an external clock (CLKEXT = 1).
Hi
We have used this ADC (MCP 3903) with our PIC32MX series board and we are reading it for a Load measurement application. Now what I want to achieve is to have 1 in 10000 stable counts but we are finding it hard to achieve.
Can you suggest how to get stable data.
Abhinav
Hola yo tambien estoy teniendo el mismo problema. Sólo con sigue ceros a la salida. ¿Cuál puede ser el fallo?
Hi I’m also having the same problem. Only zeros follows the exit. What can be the fault?
Hi everybody!
First of all thanks for the good post. I have one simple question regarding the MCP3903.
I’m measuring only positive voltage, so CHn- are all connected to GND. If I understand the datasheet correctly, the maximum Vref+ = 2.9V which mean: (-2.9V/3)<input voltage range<(+2.9V/3) or in my case: 0V<input range<(+2.9V/3)? So I can only measure voltage range up to 0.97V and with 23-bit resolution (because 1MSB is lost due to positive input signal)?
BR, Marko
Hi, I interfaced the MCP3903 to an arduino Due with the help of your library and a few modifications making use of bitbanged SPI.
I am using this ADC to measure the anguler position of a motor via a potentiometer. The problem that I am facing is that the signal from the ADC keeps varying, right upto the 12th bit. I wanted 23bit resolution, but due to this variation, I am having only as good as 8 bit resolution. Can you tell me what I may have done wrong, or whether, the ADC just works that way.
NOTE i have set the gain to 1 and OSR to 256, using internal refrence,
Hi
A chic library!! Thanks for all! At first i had some problem because i haven`t read the datasheet and inputs are [-1,1] . I have made a resistor divided for reading one sensor that has a +5v output!!
:)
If someone know the formulae for ADC when using 16bit AC signal, it will be of great help.
Hi Kerry,
last days i build up my MSP3903. Thank you for your library. I was a great help to make the first steps on this great chip. In your library there is no hint of your Copyright. Is your library CC/GNU? If yes, wich conditions you have declared?
Best regards
Jennifer
Hi Jennifer,
All code on my website are released under either FreeBSD or Apache licenses (you can pretty much do whatever you see fit with it) unless specified.
Good morning.
I am trying to test MCP3903 out using your program.
My setup uses a voltage regulator with a potentiometer as an input, It goes from 0 up to times the reference voltage (2V), the problem is whenever the voltage goes negative the serial plotter jumps to 1700 V and I can’t seem to grasp why. | http://www.kerrywong.com/2014/05/10/mcp3903-library/?replytocom=865954 | CC-MAIN-2018-39 | refinedweb | 1,796 | 74.49 |
- NAME
- DESCRIPTION
- SYNOPSIS
- FUNCTIONS
- tzset([$zone])
- tzget([$zone])
- use_system_zones()
- use_embed_zones()
- tzdir([$newdir])
- available_zones()
- tzname()
- gmtime($epoch)
- localtime($epoch)
- timegm($sec, $min, $hour, $day, $mon, $year, [$isdst])
- timegmn($sec, $min, $hour, $day, $mon, $year)
- timelocal($sec, $min, $hour, $day, $mon, $year, [$isdst])
- timelocaln($sec, $min, $hour, $day, $mon, $year, [$isdst])
- SUPPORTED OS
- C INTERFACE
- SYNOPSIS
- FUNCTIONS
- void tzset (const char* zone = NULL)
- tz* tzget (const char* zone)
- tz* tzlocal ()
- const char* tzdir ()
- bool tzdir (const char* newdir)
- const char* tzsysdir ()
- void timezone->retain ()
- void timezone->release ()
- void gmtime (time_t epoch, datetime* result)
- time_t timegm (datetime* date)
- time_t timegml (datetime* date)
- void localtime (time_t epoch, datetime* result)
- time_t timelocal (datetime* date)
- time_t timelocall (datetime* date)
- void anytime (time_t epoch, datetime* result, const tz* zone)
- time_t timeany (datetime* date, const tz* zone)
- time_t timeanyl (datetime* date, const tz* zone)
- igmtime(), itimegm(), itimegml()
- size_t strftime (char* buf, size_t maxsize, const char* format, const datetime* timeptr)
- void dt2tm (struct tm &to, datetime &from), void tm2dt (datetime &to, struct tm &from)
- CAVEATS
- PERFOMANCE
- AUTHOR
- LICENSE
NAME
Panda::Time - low-level and very efficient POSIX time/zone functions implementation in C.
DESCRIPTION.
Normally you don't need to use most of these functions directly from perl as it's interface cannot provide perfomance which these functions have at C level. You should use Panda::Date module. However you can write our own XS code using these functions or C++ Date class (from Panda::Date module).
SYNOPSIS
use Panda::Date; # ... work with Panda::Date in local zone of your server use Panda::Time 'tzset'; tzset('Europe/Moscow'); use Panda::Date; # ... work with Panda::Date in Europe/Moscow as local zone
FUNCTIONS
tzset([$zone])
Sets $zone as localzone. If you dont provide $zone, timezone of the server will be set ($ENV{TZ}, /etc/localtime, or whatever your OS considers to be localzone).
Does NOT affect POSIX:tzset(). Only this module's localtime/timelocal/etc functions and Panda::Date classes will follow this timezone.
# change local zone to 'America/New_York' tzset('America/New_York'); # the same (doesnt work in Windows) local $ENV{TZ} = 'America/New_York'; tzset(); # change localzone back to the server's localzone (in case you didn't change $ENV{TZ}) tzset(); # or tzset(undef) or tzset('')
If you don't want to change localzone, you don't have to call this function directly as it's called implicitly on-demand.
If you provide $zone and no such zone found in zones directory (or timezone file is corrupted), 'UTC0' is used.
tzget([$zone])
Returns information about timezone $zone (or about server's local zone if $zone is not provided). For information purposes only.
Example of data returned:
{ future => { hasdst => 1, outer => { end => {sec => 0, mon => 2, week => 2, hour => 2, day => 0, min => 0 }, offset => -18000, isdst => 0, gmt_offset => -18000, abbrev => 'EST' }, inner => { end => {week => 1, mon => 10, min => 0, hour => 2, day => 0, sec => 0}, offset => -14400, abbrev => 'EDT', gmt_offset => -14400, isdst => 1 } }, name => 'America/New_York', is_local => 0, past => { abbrev => 'LMT', offset => -17762 }, transitions => [ { offset => -17762, leap_delta => 0, abbrev => 'LMT', start => '-9223372036854775808', leap_corr => 0, gmt_offset => -17762, isdst => 0 }, { offset => -18000, leap_delta => 0, gmt_offset => -18000, isdst => 0, start => '-2717650800', abbrev => 'EST', leap_corr => 0 }, ... ] }
use_system_zones()
Use your OS's timezones dir. This is default behaviour if your OS has /usr/share/zoneinfo DB. Otherwise embedded zones are used by default (on MS Windows).
If your OS doesn't have /usr/share/zoneinfo DB, this function warns and does nothing.
use_embed_zones()
Use timezone files which come with this module.
tzdir([$newdir])
Sets or returns current timezones directory. If there was an error (too long path, !exists, !readable, etc) returns false and leaves tzdir unchanged.
say tzdir(); # prints /usr/share/zoneinfo (on UNIX) tzdir('/home/frank/myzones'); # use /home/frank/myzones as timezones DB say tzdir(); # prints /home/frank/myzones tzset('Europe/Moscow'); # set /home/frank/myzones/Europe/Moscow as localzone
available_zones()
Returns list of all available timezones (names) in tzdir().
tzname()
The name of localzone. Note that in some cases the real name of localzone is not known (for example when localzone is retrieved from /etc/localtime file, tzname() will return ':/etc/localtime')
gmtime($epoch)
Behaves exactly like perl's gmtime.
The returned year is in human-readable form (not year-1900). Month is [0-11]. The same applies for all further time functions.
localtime($epoch)
Behaves exactly like perl's localtime.
timegm($sec, $min, $hour, $day, $mon, $year, [$isdst])
Behaves exactly like POSIX's timegm.
timegmn($sec, $min, $hour, $day, $mon, $year)
Same as timegm() except for the arguments which have to be non-constant values because they are normalized during calculations.
timelocal($sec, $min, $hour, $day, $mon, $year, [$isdst])
Behaves exactly like POSIX's timelocal.
timelocaln($sec, $min, $hour, $day, $mon, $year, [$isdst])
Same as timelocal() except for the arguments which have to be non-constant values because they are normalized during calculations.
SUPPORTED OS
Tested on FreeBSD, Linux, MacOSX, Windows 2003, Windows 7.
I believe all of UNIX-like and Windows-like systems are supported.
Timezones are supported in Olson DB format (V1,2,3).
C INTERFACE
SYNOPSIS
All functions/types/constants are in panda::time:: namespace (so actually you need C++ to use them).
#include <stdio.h> #include <panda/time.h> using panda::time::tzset; using panda::time::localtime; tzset('Europe/Moscow'); time_t epoch = 1000000000; datetime date; localtime(epoch, &date); printf( "epoch %lli is %04d/%02d/%02d %02d:%02d:%02d, isdst=%d, GMT offset is %d, zone abbreviation is %s", epoch, date.year, date.mon+1, date.mday, date.hour, date.min, date.sec, date.isdst, date.gmtoff, date.zone ); epoch = timelocal(&date);
FUNCTIONS
void tzset (const char* zone = NULL)
See "tzset([$zone])".
tz* tzget (const char* zone)
Returns timezone object pointer which contains info about timezone 'zone' (or about server's local zone if zone == NULL or "").
You can then use this pointer to perform time calculations in any zone you want without setting local zone via
tzset(). You can also have as many timezones in parralel as you want.
Remember that this pointer is only valid until next
tzdir(newdir) and possibly
tzset() call. If you want this zone pointer to be valid forever call
retain() on timezone object.
When you call
tzget(zone) for the first time it reads and parses timezone file from disk. Futher calls with the same zone returns cached pointer.
tz* tzlocal ()
Same as
tzget(NULL).
const char* tzdir ()
Returns current timezone DB directory.
bool tzdir (const char* newdir)
See "tzdir([$newdir])".
tzdir(NULL) sets tzdir to tzsysdir().
const char* tzsysdir ()
Returns system timezones dir if any (usually /usr/share/zoneinfo), otherwise returns NULL.
void timezone->retain ()
Captures timezone object so that it remains valid until
timezone-release()> call.
void timezone->release ()
Releases timezone object so that it can be removed from memory if no longer used by any other consumers.
Remember: you must not call
release() unless you've called
retain().
void gmtime (time_t epoch, datetime* result)
Behaves like POSIX's
gmtime_r() but much faster.
The returned year is in human-readable form (not year-1900). Month is [0-11]. The same applies for all further time functions.
time_t timegm (datetime* date)
Behaves like POSIX's
timegm() but much faster.
time_t timegml (datetime* date)
More efficient (lite) version of
timegm(), doesn't change (normalize) values in date.
void localtime (time_t epoch, datetime* result)
Behaves like POSIX's
localtime_r() but much faster.
time_t timelocal (datetime* date)
Behaves like POSIX's
timelocal() but much faster.
time_t timelocall (datetime* date)
More efficient (lite) version of
timelocal(), doesn't change (normalize) values in date.
void anytime (time_t epoch, datetime* result, const tz* zone)
Performs epoch -> datetime calculations in timezone 'zone'.
The following two lines are equivalent:
localtime(epoch, date); anytime(epoch, date, tzlocal());
time_t timeany (datetime* date, const tz* zone)
Performs datetime -> epoch calculations in timezone 'zone'.
The following two lines are equivalent:
epoch = timelocal(date); epoch = timeany(date, tzlocal());
time_t timeanyl (datetime* date, const tz* zone)
More efficient (lite) version of
timeany(), doesn't change (normalize) values in date.
igmtime(), itimegm(), itimegml()
Inline versions for even more perfomance.
size_t strftime (char* buf, size_t maxsize, const char* format, const datetime* timeptr)
Behaves like POSIX's
strftime().
void dt2tm (struct tm &to, datetime &from), void tm2dt (datetime &to, struct tm &from)
Performs struct tm <-> struct datetime convertations
CAVEATS
$ENV{TZ} doesn't work in Windows. To set $zone as localzone, you should write
tzset($zone);
to produce platform-independent code.
While developing all the time functions from scratch and comparing results with POSIX's system functions i discovered that many operating systems have buggy implementations of localtime/timelocal functions which causes them to return wrong results in case of certain dates (actually rare dates). Therefore in such cases the result of panda::time::* functions won't match with POSIX functions because panda::time handles all these cases correctly.
Bugs i discovered (exact times may for now differ as many timezones have changed since i first wrote this):
Linux and FreeBSD (and possibly more Unix-like systems)
- timelocal cannot correctly handle forward time jump at last transition.
For example Europe/Moscow, date "2011/03/27 02:00:00" Must return 1301180400 ("2011/03/27 03:00:00") In fact returns - linux: 1301176800 ("2011/03/27 01:00:00") - freebsd: -1 If transition is not the last one, it works correctly: "2010/03/28 02:00:00" returns 1269730800 ("2010/03/28 03:00:00")
- localtime/timelocal handles DST transitions in future (outside of transitions) incorrectly when using leap second zones
$ TZ=right/Australia/Melbourne perl -E 'say scalar localtime 4284028799' Sun Oct 4 01:59:34 2105 $ TZ=right/Australia/Melbourne perl -E 'say scalar localtime 4284028800' Sun Oct 4 02:59:35 2105
FreeBSD only
- America/Anchorage timezone behaves like it has no POSIX string (no DST changes after last transition)
-
- timelocal cannot handle dates before year 1900
-
- Wrong forward jump normalization with non-DST transitions
- Simple forward jump 1h somewhy normalized back CORRECT: epoch=-1539492257 (1921/03/21 00:15:43 MSD) from 1921/03/20 23:15:43 DST=-1 (Europe/Moscow) POSIX: epoch=-1539495857 (1921/03/20 22:15:43 MSD) from 1921/03/20 23:15:43 DST=-1 (Europe/Moscow) - Forward jump 2h normalized just 1h CORRECT: epoch=-1627961251 (1918/06/01 01:03:17 MDST) from 1918/05/31 23:03:17 DST=-1 (Europe/Moscow) POSIX: epoch=-1627964851 (1918/06/01 00:03:17 MDST) from 1918/05/31 23:03:17 DST=-1 (Europe/Moscow) - Simple forward jump 1h somewhy normalized 30min CORRECT: epoch=372787481 (1981/10/25 03:34:41 LHST) from 1981/10/25 02:34:41 DST=-1 (Australia/Lord_Howe) POSIX: epoch=372785681 (1981/10/25 03:04:41 LHST) from 1981/10/25 02:34:41 DST=-1 (Australia/Lord_Howe) - Simple forward jump 1h somewhy normalized 2h CORRECT: epoch=449595541 (1984/04/01 01:39:01 CHOST) from 1984/04/01 00:39:01 DST=-1 (Asia/Choibalsan) POSIX: epoch=449599141 (1984/04/01 02:39:01 CHOST) from 1984/04/01 00:39:01 DST=-1 (Asia/Choibalsan) - Forward jump 3h normalized 2h CORRECT: epoch=354905851 (1981/04/01 04:57:31 MAGST) from 1981/04/01 01:57:31 DST=-1 (Asia/Ust-Nera) POSIX: epoch=354902251 (1981/04/01 03:57:31 MAGST) from 1981/04/01 01:57:31 DST=-1 (Asia/Ust-Nera)
Linux only
- Complex bug with static variable deep inside POSIX code
Steps to reproduce: (TZ=Europe/Moscow, date strings are for compactness, actually 'struct tm' required)
mktime("1998/10/25 03:-1:61"); // returns 909273601 (Sun Oct 25 03:00:01 1998) - that's ok mktime("2011/-2/1 00:00:00"); // returns 1285876800 (Fri Oct 1 00:00:00 2010) - that's ok // now run the first line again mktime("1998/10/25 03:-1:61"); // returns 909270001 (Sun Oct 25 02:00:01 1998) - OOPS // again and again mktime("1998/10/25 03:-1:61"); // returns 909270001 (Sun Oct 25 02:00:01 1998) - OOPS forever :(
PERFOMANCE
Tests were performed on MacOSX Lion, Core i7 3.2Ghz, clang 3.3.
------------------------------------------------------------------------------------------------- | Function | panda | libc(MacOSX) | libc(Linux) | libc(FreeBSD) | ------------------------------------------------------------------------------------------------- | gmtime(epoch, &date) | 53 M/s | 11 M/s | 15 M/s | 12 M/s | | timegm(&date) | 30 M/s | 0.4 M/s | 10 M/s | 0.15 M/s | | timegml(&date) | 135 M/s | -- | -- | -- | | localtime(epoch, &date) | 26 M/s | 5.5 M/s | 7 M/s | 3 M/s | | timelocal(&date) | 23 M/s | 0.5 M/s | 1.2 M/s | 0.1 M/s | | timelocall(&date) | 50 M/s | -- | -- | -- | -------------------------------------------------------------------------------------------------
AUTHOR
Pronin Oleg <syber@cpan.org>, Crazy Panda, CP Decision LTD
LICENSE
You may distribute this code under the same terms as Perl itself. | https://metacpan.org/pod/Panda::Time | CC-MAIN-2015-27 | refinedweb | 2,113 | 59.23 |
class Base(object):
def m(self):
print 'base'
class MixinA(Base):
def m(self):
super(MixinA, self).m()
print 'mixin a'
class MixinB(Base):
def m(self):
super(MixinB, self).m()
print 'mixin b'
class Top(MixinB, MixinA, Base):
def m(self):
super(Top, self).m()
print 'top'
t = Top()
t.m()
base
mixin a
mixin b
top
Top
(<class 'Top'>, <class 'MixinB'>, <class 'MixinA'>, <class 'Base'>, <type 'object'>)
mixin a
mixin b
super
No,
super() does not 'try' each class in the MRO. Your code chains the calls, because each method called has another
super() call in it.
Top.m() calls
super().m(), which resolves to
MixinB.m(); which in turn uses
super() again, etc.
mixin a is printed before
mixin b because you are printing after the
super() call, so the last element in the MRO is executed first. The
super() call is just another method call, so a
super().m() call has completed.
Your MRO is as follows:
>>> type(t).__mro__ (<class '__main__.Top'>, <class '__main__.MixinB'>, <class '__main__.MixinA'>, <class '__main__.Base'>, <type 'object'>)
so naturally
Base.m() is called last and gets to print first, followed by
MixinA, then
MixinB, and
Top being the last to print.
Note that the MRO of
self is used, not of the class you pass into
super() as the first argument; the MRO is thus stable throughout all calls in your hierarchy for any given instance.
If you expected the print statements to be executed in the order the MRO calls are chained, you'll have to put the
m() method in the MRO. | https://codedump.io/share/ckVSwAtEnBRP/1/does-super-try-each-class-in-mro | CC-MAIN-2017-13 | refinedweb | 265 | 76.93 |
:-)
JRS server on Mac OS
server.startup
server.shutdown
Jazz is for everyone
Looks.
"J" is for Jazz, not Java.
JRS and JCR (JSR-170)
"Every node has one and only one primary node type. A primary node type
defines the characteristics of the node, such as the properties and
child nodes that the node is allowed to have. In addition to the primary
node type, a node may also have one or more mixin types. A mixin type
acts a lot like a decorator, providing extra characteristics to a node.
A JCR implementation, in particular, can provide three predefined mixin
types...".
Develop with Jazz, for Jazz, and on a Mac.
Jazz REST Services!
64-core ThinkPad anyone?
Via /.?
Erlang on IBM blogs
I.
Beautiful Code, Safe Code.
Another lesson I have learned is.
Cool Django
from django.db.models.fields import CharField
class
import
isValidRegularExpression.always_test = True
There are a few more Django tweaks as well as some tips/tricks we found that hopefully I can post over the next week or so.
Python and XPath (as an) API
Python.
Eric the sheep
Here's a little fun aside for you, a problem I sat down with three adults a 10 year old and a 7 year old. The problem concerns a happy chap by the name of Eric the Sheep, which I sill summarize below (visit the site though there are some really interesting problems for kids).
Eric the sheep is lining up to be shorn before the hot summer ahead. There are fifty [50] sheep in front of him. Eric can't be bothered waiting in the queue properly, so he decides to sneak towards the front. Every time Eric passes two sheep, one sheep from the front of the line is taken in to be shorn. How many sheep will be shorn before Eric?
Well once we were close to the answer, and being a geek at heart, out came the ThinkPad and Python for a quick solution check ... so enjoy this.
More offers | http://www.ibm.com/developerworks/blogs/page/johnston/20080430 | crawl-001 | refinedweb | 338 | 76.11 |
Edit : instead of buffering in Hash and then emitting at cleanup you can
use a combiner. Likely slower but easier to code if speed is not your
main concern
Le 01/03/2015 13:41, Ulul a écrit :
> Hi
>
> I probably misunderstood your question because my impression is that
> it's typically a job for a reducer. Emit "local" min and max with two
> keys from each mapper and you will easily get gobal min and max in reducer
>
> Ulul
> Le 28/02/2015 14:10, Shahab Yunus a écrit :
>> As far as I understand cleanup is called per task. In your case I.e.
>> per map task. To get an overall count or measure, you need to
>> aggregate it yourself after the job is done.
>>
>> One way to do that is to use counters and then merge them
>> programmatically at the end of the job.
>>
>> Regards,
>> Shahab
>>
>> On Saturday, February 28, 2015, unmesha sreeveni
>> <unmeshabiju@gmail.com <mailto:unmeshabiju@gmail.com>> wrote:
>>
>>
>> I am having an input file, which contains last column as class label
>> 7.4 0.29 0.5 1.8 0.042 35 127 0.9937 3.45 0.5 10.2 7 1
>> 10 0.41 0.45 6.2 0.071 6 14 0.99702 3.21 0.49 11.8 7 -1
>> 7.8 0.26 0.27 1.9 0.051 52 195 0.9928 3.23 0.5 10.9 6 1
>> 6.9 0.32 0.3 1.8 0.036 28 117 0.99269 3.24 0.48 11 6 1
>> ...................
>> I am trying to get the unique class label of the whole file.
>> Inorder to get the same I am doing the below code.
>>
>> /public class MyMapper extends Mapper<LongWritable, Text,
>> IntWritable, FourvalueWritable>{/
>> / Set<String> uniqueLabel = new HashSet();/
>> /
>> /
>> / public void map(LongWritable key,Text value,Context context){/
>> / //Last column of input is classlabel./
>> / Vector<String> cls = CustomParam.customLabel(line,
>> delimiter, classindex); // /
>> / uniqueLabel.add(cls.get(0));/
>> / }/
>> / public void cleanup(Context context) throws IOException{/
>> / //find min and max label/
>> / context.getCounter(UpdateCost.MINLABEL).setValue(Long.valueOf(minLabel));/
>> / context.getCounter(UpdateCost.MAXLABEL).setValue(Long.valueOf(maxLabel));/
>> /}/
>> Cleanup is only executed for once.
>>
>> And after each map whether "Set uniqueLabel = new HashSet();" the
>> set get updated,Hope that set get updated for each map?
>> Hope I am able to get the uniqueLabel of the whole file in cleanup
>> Please suggest if I am wrong.
>>
>> Thanks in advance.
>>
>>
> | http://mail-archives.apache.org/mod_mbox/hadoop-hdfs-user/201503.mbox/%3C54F30B2D.8020203@ulul.org%3E | CC-MAIN-2018-26 | refinedweb | 406 | 67.45 |
Sample Data: C1, C2 and C3 represents three different class of data. It is guaranteed that these data set are linearly separable.
Problem statement:- Write a program to generate
1.linear classifier for class C1 and C2
2. linear classifier for class C2 and C3
Sample code: -
import sys import matplotlib.pyplot as plt import numpy as np # Make a prediction with weights def compute(row, weights): bias = weights[2] output = bias #output = (w1 * X1) + (w2 * X2) + bias for i in range(len(row)-1): output += weights[i] * row[i] ##print "output is",output return 1 if output > 0 else 0 #extrapolate classifer line with same slope as computed by final weights def getMultiplePoints(x,y,weight,boundX1,boundX2): x1 =[x,0] x2 =[0,y] pointsX = [] pointsY = [] pointsX.insert(1,y) pointsX.insert(2,0) pointsY.insert(1,0) pointsY.insert(2,x) #for boundX1 pointsX.insert(0,boundX1) temp = -(weight[0]*boundX1 + weight[2])/weight[1] pointsY.insert(0,temp) #for boundX2 pointsX.insert(3,boundX2) temp = -((weight[0]*boundX2) + weight[2])/weight[1] pointsY.insert(3,temp) return (pointsX,pointsY) #plot points def plotCoordinates(dataset,weightPlot): XList1 =[] YList1 =[] XList2 =[] YList2 =[] count = 0 boundX = -8 boundY = 10 x1 = - (weightPlot[2]/weightPlot[1]) y1 = 0 x2 = 0 y2 = - (weightPlot[2]/weightPlot[0]) #print x1 , y2 # compute some random point with slope as W and bias b plotTup = getMultiplePoints(x1,y2,weightPlot,boundX,boundY) for row in dataset: if(count<=9): XList1.append(row[0]) YList1.append(row[1]) else: XList2.append(row[0]) YList2.append(row[1]) count = count+1 #Draw points with red and Blue color plt.plot(XList1, YList1, 'ro',XList2, YList2, 'bo') plt.axis([boundX, boundY, boundX, boundY]) plt.plot(plotTup[0],plotTup[1]) plt.show() #Update weight and bias def updateWeight(weights,x,l_rate,error): #update bias weights[2] = weights[2] + x[2] + l_rate * error #update weight part w1, w2 for i in range(len(x)-1): weights[i] = weights[i] + l_rate * error * x[i] return weights #Find linear classifier, predit outcome for each point and if error compute weight def findPerceptronClassifier(dataset,weights): flag = True epoch = 0 retList = [] l_rate = 0.2 count = 0 #lastWeight = [] while(flag): #flag = False epoch = epoch + 1 #print("\nepoch = epoch + 1 is %d\n",epoch) count = 0 for row in dataset: predicted_val = compute(row, weights) error = row[-1] - predicted_val #update weights if error != 0: weights = updateWeight(weights,row,l_rate,error) count = count + 1 lastWeight = weights if error == 0 and count == 0: flag = False else: flag = True retList.append(epoch) #print "Weight is ",weights #print "last Weight is ",lastWeight retList.append(weights) return retList # Input dataset for classifier datasetC1C2 =[[0.1,1.1,0], [6.8 ,7.1,0], [-3.5 ,-4.1,0], [2.0 ,2.7,0] , [4.1 ,2.8,0] , [3.1 ,5.0,0], [-0.8 ,-1.3,0],[0.9 ,1.2,0], [5.0 ,6.4,0], [3.9, 4.0]] datasetC2C3 = [[-3.0 , -2.9,0], [0.5, 8.7,0], [2.9 , 2.1,0], [-0.1, 5.2,0], [-4.0 , 2.2,0], [-1.3, 3.7,0], [-3.4, 6.2,0], [-4.1, 3.4,0], [-5.1, 1.6,0], [1.9 , 5.1]] #initialize inital weight and bias initial_weights = [0,0,0] #Iteration count epoch = 0 outList = [] def C1C2Classifier(): #Iteration count for convergence - Dataset C1 and C2 outList = findPerceptronClassifier(datasetC1C2,initial_weights) epoch = outList[0] weightPlot = outList[1] ##print "Weight plot is ",weightPlot plotCoordinates(datasetC1C2,weightPlot) def C2C3Classifier(): #Iteration count for convergence - Dataset C2 and C3 outList = findPerceptronClassifier(datasetC2C3,initial_weights) epoch = outList[0] weightPlot = outList[1] ##print "Weight plot is ",weightPlot plotCoordinates(datasetC2C3,weightPlot) # map the inputs to the function blocks options = { 1 : C1C2Classifier, 2 : C2C3Classifier, } #start if __name__ == '__main__': print "1. Run C1C2 classifier \n2. Run C2C3 classifier\n" print "Enter your choice:\t" num = int(raw_input()) options[num]()
Sample output:-
[zytham@s158519-vm perceptron]$ python Perceptron.py
1. Run C1C2 classifier
2. Run C2C3 classifier
Enter your choice: 1
[zytham@s158519-vm perceptron]$ python Perceptron.py
1. Run C1C2 classifier
2. Run C2C3 classifier
Enter your choice:
2
Your post is really awesome .it is very helpful for me to develop my skills in a right way
Selenium Training in Bangalore
Very nice blog i really enjoyed to read this blog, continue to post useful | https://www.devinline.com/2017/05/perceptron-learning-in-python.html | CC-MAIN-2020-29 | refinedweb | 719 | 53.51 |
Win a copy of Barcodes with iOS this week in the iOS forum or Core Java for the Impatient in the Java 8 forum!
Volodymyr Levytskyi wrote:I have already explained everything and if you read at least you would know.
The problem is that static fields cannot contain generic types of class. This is not possible.
For instance DVTooltip has method :
void ADD(T t){ . .................................}
where T is <T extends DatabaseModel>.
But single instance dvTooltip that calls this method ADD has its generic type as <? extends DatabaseModel>.
Volodymyr Levytskyi wrote:But if I try to make single instance dvTooltip have generic type T it fails telling :
Cannot make a static reference to the non-static type T
Volodymyr Levytskyi wrote:This does not compile:
interface DatabaseModel {
}
class Column implements DatabaseModel {
}
public class Demo1<T extends DatabaseModel> {
public static final Demo1<? extends DatabaseModel> demo = new Demo1<>();
public void ADD(T t) {
// does nothing
}
public static void main(String[] args) {
demo.ADD(new Column());
}
}
But I cannot replace generic type of demo instance with generic type T.
Volodymyr Levytskyi wrote:Thanks @Raymond for this excellent reply!
Winston Gutkowski wrote: The problem with ? super ... is that it then allows anything in the hierarchy, including Object.
Piet Souris wrote:
No, it doesn't.
Look at this code:
Piet Souris wrote:No, it doesn't.
Look at this code:
Winston Gutkowski wrote:I'm surprised that you actually got that code to compile, since wildcards aren't supposed to be allowed on the right-hand side of an assignment statement, let alone with the new keyword; but I have to admit to not having used the diamond operator yet.
Matthew Brown wrote:It's safe because of type erasure.
Matthew Brown wrote:It's safe because of type erasure. Since at runtime it doesn't actually matter which generic type is chosen, all the compiler needs to worry about is that there is a generic type that's compatible. And there is at least one: P.
Matthew Brown wrote:Both should compile down to the same compiled code. Which means that the diamond operator is safe.
Winston Gutkowski wrote:
Matthew Brown wrote:Both should compile down to the same compiled code. Which means that the diamond operator is safe.
Sorry, but I have to disagree (and if it does work that way, then it's a huge error in my book).
The diamond operator is strictly a convenience to save you typing (or it damn well should be; otherwise I suspect we're going to see a LOT of questions like this).
So to my mind, Piet's assignment:
ArrayList<? super P> ar = new ArrayList<>();
is exactly the same as:
ArrayList<? super P> ar = new ArrayList<? super P>();
and THAT produces the compile error I showed above.
Winston
Matthew Brown wrote:According to the warnings by IDE generates, List<? super Number> list = new ArrayList<>() infers the type as Object, and List<? extends Number> list = new ArrayList<>() infers the type as Number, which makes sense to me: it's taking the least specific possible for super and the most specific possible for extends.
Matthew Brown wrote:According to the warnings by IDE generates, List<? super Number> list = new ArrayList<>() infers the type as Object (...)
Piet Souris wrote:And although Winston has his doubts about how Oracle implemented the diamond operator, I'm glad it's there. It does save a lot of typing!
Chan Ag wrote:
interface DatabaseModel {
}
class Column implements DatabaseModel {
}
public class Demo1<T extends DatabaseModel> {
public <T> void method1(T t) { // this method T is not the same T as the class T
System.out.println("Hello");
}
public void method2() {
method1(new Column());
}
}
Chan Ag wrote:I just read Winston's first response again and now I see what I was missing.
Martin Vajsar wrote:Hah, Winston, you've made me install JDK7! Thanks!
I really think that you aren't being fair to Oracle in your assessment of the diamond operator...
Diamond operator inherits the complications to some extent...
Winston Gutkowski wrote:Don't like 'em, never will; and I think their database is crap (probably too much time spent forcing the square peg of 8i into Linux's round hole)
Volodymyr Levytskyi wrote:I think that generic type <T extends DatabaseModel> for class works diffrently than <T extends DatabaseModel> for method.
And why is that? | http://www.coderanch.com/t/622452/java/java/wrong-Generics | CC-MAIN-2015-11 | refinedweb | 725 | 64.41 |
I have bought the 1.2" 4x7-segment display with the LED backpack, and I intended to use it with a feather.
The display and everything else works flawlessly on my Raspberry Pi Zero, and in the process of figuring out the issue I trimmed everything down to the following minimal code:
- Code: Select all | TOGGLE FULL SIZE
import board
i2c = board.I2C()
while not i2c.try_lock()
pass
i2c.writeto(0x70, bytearray([0x21]))
i2c.writeto(0x70, bytearray([0x81]))
i2c.writeto(0x70, bytearray([4, 2]))
i2c.unlock()
I get the expected result of having the central dots lighted up, most of the time only that though sometime there is some garbage data on the other registers.
This proves that the display works fine, my wire are good, and I can understand a wiring diagram (none of these were obvious before testing).
So I proceeded to try and use it with my feather STM32, and I got an error on the first write. However, this board already has some quirks (see) and I don't know how to ensure the I2C part of the board works as it should. Moreover, I program this board with Ada Drivers Library, so that's a bit too many unknowns on the line.
I also have a feather M0, with the embedded ATWINC1500 wifi thingy, and I flashed CircuitPython on it (admittedly this was not a good idea, but AFAICT it's still a good circuitpython as long as I pretend there is no wifi chip). So I used the python code quoted above, and it also failed, with "OSError: [Errno 5] Input/output error"
I tried going in REPL mode, and I could confirm that i2c.scan() returns an empty list on the feather M0, while on the raspberry pi it returns a single-item list with 112 (i.e. 0x70).
I wondered whether the USB pin of the feather might not be 5V, so I also tried wiring pi's 5V and GND to the backpack, pi GND to feather GND, and feather's 3.3V, SDA and SCL to the backpack, but it still didn't work.
At this point I have no idea what else to try. Would you have any idea on how to further understand the issue?
Thanks in advance. | https://forums.adafruit.com/viewtopic.php?f=47&t=183431 | CC-MAIN-2022-05 | refinedweb | 380 | 79.7 |
- NAME
- DESCRIPTION
- Core Enhancements
- Postfix dereferencing is no longer experimental
- Unicode 8.0 is now supported
- perl will now croak when closing an in-place output file fails
- New \b{lb} boundary in regular expressions
- qr/(?[ ])/ now works in UTF-8 locales
- Integer shift (<< and >>) now more explicitly defined
- printf and sprintf now allow reordered precision arguments
- More fields provided to sigaction callback with SA_SIGINFO
- Hashbang redirection to Perl 6
-
perldelta - what is new for perl v5.24.0
DESCRIPTION
This document describes the differences between the 5.22.0 release and the 5.24.0 release.
Core Enhancements
Postfix dereferencing is no longer experimental
Using the
postderef and
postderef_qq features no longer emits a warning. Existing code that disables the
experimental::postderef warning category that they previously used will continue to work. The
postderef feature has no effect; all Perl code can use postfix dereferencing, regardless of what feature declarations are in scope. The
5.24 feature bundle now includes the
postderef_qq feature.
Unicode 8.0 is now supported
For details on what is in this release, see..
New
\b{lb} boundary in regular expressions
lb stands for Line Break. It is a Unicode property that determines where a line of text is suitable to break (typically so that it can be output without overflowing the available horizontal space). This capability has long been furnished by the Unicode::LineBreak module, but now a light-weight, non-customizable version that is suitable for many purposes is in core Perl.
qr/(?[ ])/ now works in UTF-8 locales
Extended Bracketed Character Classes now will successfully compile when.
Integer shift (
<< and
>>) now more explicitly defined
Negative shifts are reverse shifts: left shift becomes right shift, and right shift becomes left shift.
Shifting by the number of bits in a native integer (or more) is zero, except when the "overshift" is right shifting a negative value under
bigint pragma, or the
Bit::Vector module from CPAN.
printf and sprintf now allow reordered precision arguments
That is,
sprintf '|%.*2$d|', 2, 3 now returns
|002|. This extends the existing reordering mechanism (which allows reordering for arguments that are used as format fields, widths, and vector separators).
More fields provided to
sigaction callback with
SA_SIGINFO
When passing the
SA_SIGINFO flag to sigaction, the
errno,
status,
uid,
pid,
addr and
band fields
mkstemp(3)
In 5.22]
Fix out of boundary access in Win32 path handling
This is CVE-2015-8608. For more information see [perl #126755]
Fix loss of taint in canonpath
This is CVE-2015-8607. For more information see [perl #126862]
Avoid accessing uninitialized memory in win32
crypt()
Added validation that will detect both a short salt and invalid characters in the salt. [perl #126922].
Second, we remove duplicates from
environ[], so if a setting with that name is set in
%ENV, we won't pass an unsafe value to a child process.
[CVE-2016-2381]
Incompatible Changes
The
autoderef feature has been removed
The experimental
autoderef feature (which allowed calling
push,
pop,
shift,
unshift,
splice,
keys,
values, and
each on a scalar argument) has been deemed unsuccessful. It has now been removed; trying to use the feature (or to disable the
experimental::autoderef warning it previously triggered) now yields an exception.
Lexical $_ has been removed.
qr/\b{wb}/ is now tailored to Perl expectations
This is now more suited to be a drop-in replacement for plain
\b, but giving better results for parsing natural language. Previously it strictly followed the current Unicode rules which calls for it to match between each white space character. Now it doesn't generally match within spans of white space, behaving like
\b does. See "\b{wb}" in perlrebackslash
Regular expression compilation errors
Some regular expression patterns that had runtime errors now don't compile at all.
Almost all Unicode properties using the
\p{}.
qr/\N{}/ now disallowed under
use re "strict"
An empty
\N{} makes no sense, but for backwards compatibility is accepted as doing nothing, though a deprecation warning is raised by default. But now this is a fatal error under the experimental feature "'strict' mode" in re.
Nested declarations are now disallowed
A
my,
our, or
state declaration is no longer allowed inside of another
my,
our, or
state declaration.
For example, these are now fatal:
my ($x, my($y)); our (my $x);
utf8::encode() on the string (or a copy) first.
chdir('') no longer chdirs home
Using
chdir('') or
chdir(undef) to chdir home has been deprecated since perl v5.8, and will now fail. Use
chdir() instead.
ASCII characters in variable names must now be all visible
It was legal until now on ASCII platforms for variable names to contain non-graphical ASCII control characters (ordinals 0 through 31, and 127, which are the C0 controls
$^] and
${^GLOBAL_PHASE}. Details are at perlvar. It remains legal, though unwise and deprecated (raising a deprecation warning), to use certain non-graphic non-ASCII characters in variables names when not under
use utf8. No code should do this, as all such variables are reserved by Perl, and Perl doesn't currently define any of them (but could at any time, without notice).
An off by one issue in
$Carp::MaxArgNums has been fixed
$Carp::MaxArgNums is supposed to be the number of arguments to display. Prior to this version, it was instead showing
$Carp::MaxArgNums + 1 arguments, contrary to the documentation.
Only blanks and tabs are now allowed within
[...] within
(?[...]).
\t and SPACE characters. Previously, it was any white space. See "Extended Bracketed Character Classes" in perlrecharclass.
Deprecations
Using code points above the platform's
IV_MAX is now deprecated
Unicode defines code points in the range
0..0x10FFFF. Some standards at one time defined them up to 2**31 - 1, but Perl has allowed them to be as high as anything that will fit in a word on the platform being used. However, use of those above the platform's
IV_MAX is broken in some constructs, notably
tr///, regular expression patterns involving quantifiers, and in some arithmetic and comparison operations, such as being the upper limit of a loop. Now the use of such code points raises a deprecation warning, unless that warning category is turned off.
IV_MAX is typically 2**31 -1 on 32-bit platforms, and 2**63-1 on 64-bit ones.
split and
map ord. In the future, this warning will be replaced by an exception.
sysread(),
syswrite(),
recv() and
send() are deprecated.
ucfirst()) or match caselessly (
qr//i). This will speed up a program, such as a web server, that can operate on multiple languages, while it is operating on a caseless one.
/fixed-substr/has been made much faster.
On platforms with a libc
memchr(), e.g. 32-bit ARM Raspberry Pi, there will be a small or little speedup. Conversely, some pathological cases, such as
"ab" x 1000 =~ /aa/will be slower now; up to 3 times slower on the rPi, 1.5x slower on x86_64..
.cfile that XSUBs and const subs came from. On startup (
- perlbug@perl.org, and we will write a conversion script for you.
-
tr///and
y///fixed for
\N{}, and
use utf8ranges
Perl v5.22 introduced the concept of portable ranges to regular expression patterns. A portable range matches the same set of characters no matter what platform is being run on. This concept is now extended to
tr///. See
tr///.
There were also some problems with these operations under
use utf8, which are now fixed
- FreeBSD
Use the
fdclose()function from FreeBSD if it is available. [perl #126847]
-]
- MacOS X
export MACOSX_DEPLOYMENT_TARGET=10.Nbefore. [perl #126240]
- Solaris.
- Tru64
Workaround where Tru64 balks when prototypes are listed as
PERL_STATIC_INLINE, but where the test is build with
-DPERL_NO_INLINE_FUNCTIONS.
- VMS
On VMS, the math function prototypes in
math.hare now visible under C++. Now building the POSIX extension with C++ will no longer crash.
VMS has had
setenv/
unsetenvsince v7.0 (released in 1996),
Perl_vmssetenvnow always uses
setenv/
unsetenv.
Perl now implements its own
killpgby
$pid.
For those
%ENVelements based on the CRTL environ array, we've always preserved case when setting them but did look-ups only after upcasing the key first, which made lower- or mixed-case entries go missing. This problem has been corrected by making
%ENVelements derived from the environ array case-sensitive on look-up as well as case-preserving on store.
USE_NO_REGISTRYhas\Perland
HKEY_LOCAL_MACHINE\Software\Perlto lookup certain values, including
%ENVvars starting with
PERLhas changed. Previously, the 2 keys were checked for entries at all times through the perl process's life time even if they did not exist. For performance reasons, now, if the root key (i.e.
HKEY_CURRENT_USER\Software\Perlor
HKEY_LOCAL_MACHINE\Software\Perl) does not exist at process start time, it will not be checked again for
%ENVoverride entries for the remainder of the perl process's life. This more closely matches Unix behavior in that the environment is copied or inherited on startup and changing the variable in the parent process or another process or editing .bashrc will not change the environmental variable in other existing, running, processes.
$^E, and the relevant
WSAE*error codes are now exported from the Errno and POSIX modules for testing this against.
The previous behavior of putting the errors (converted to POSIX-style
E*error codes since Perl 5.20.0) into
$
$!against
E*constants for Winsock errors to instead test
$^Eagainst
PUSHBLOCK(),
POPSUB()etc. macros have been replaced with static inline functions such as
cx_pushblock(),
cx_popsub()etc. These use function args rather than implicitly relying on local vars such as
gimmeand
newspbeing available. Also their functionality has changed: in particular,
cx_popblock()no longer decrements
cxstack_ix. The ordering of the steps in the
pp_leave*functions involving
cx_popblock(),
cx_popsub()etc. has changed. See the new documentation, "Dynamic Scope and the Context Stack" in perlguts, for details on how to use them.
Various macros, which now consistently have a CX_ prefix, have been added:
CX_CUR(), CX_LEAVE_SCOPE(), CX_POP()
or renamed:
CX_POP_SAVEARRAY(), CX_DEBUG(), CX_PUSHSUBST(), CX_POPSUBST()
cx_pushblock()now saves
PL_savestack_ixand
PL_tmps_floor, so
pp_enter*and
pp_leave*no longer do
ENTER; SAVETMPS; ....; LEAVE
cx_popblock()now also restores
PL_curpm.
In
dounwind()for every context type, the current savestack frame is now processed before each context is popped; formerly this was only done for sub-like context frames. This action has been removed from
cx_popsub()and placed into its own macro,
CX_LEAVE_SCOPE(cx), which must be called before
cx_popsub()etc.
dounwind()now also does a
cx_popblock()on the last popped frame (formerly it only did the
cx_popsub()etc. actions on each frame).
The temps stack is now freed on scope exit; previously, temps created during the last statement of a block wouldn't be freed until the next
nextstatefollowing the block (apart from an existing hack that did this for recursive subs in scalar context); and in something like
f(g()), the temps created by the last statement in
g()would formerly not be freed until the statement following the return from
f().
@_in
cx_pushsub()and
cx_popsub()has been considerably tidied up, including removing the
argarrayfield from the context struct, and extracting out some common (but rarely used) code into a separate function,
clear_defarray(). Also, useful subsets of
cx_popsub()which had been unrolled in places like
pp_gotohave been gathered into the new functions
cx_popsub_args()and
cx_popsub_common().
pp_leavesuband
pp_leavesublvnow use the same function as the rest of the
pp_leave*'s to process return args.
CXp_FOR_PADand
CXp_FOR_GVflags have been added, and
CXt_LOOP_FORhas been split into
CXt_LOOP_LIST,
CXt_LOOP_ARY.]. [perl #126845]
::has been replaced by
__in
ExtUtils::ParseXS, like it's done for parameters/return values. This is more consistent, and simplifies writing XS code wrapping C++ classes into a nested Perl namespace (it requires only a typedef for
Foo__Barrather than two, one for
Foo_Barand the other for
Foo::Bar).
intto
void. It previously has always returned
0since Perl 5.000 stable but that was undocumented. Although
sv_backoffis marked as public API, XS code is not expected to be impacted since the proper API call would be through public API
sv_setsv(sv, &PL_sv_undef), or quasi-public
SvOOK_off, or non-public
SvOK_offcalls, and the return value of
sv_backoffwas previously a meaningless constant that can be rewritten as
(sv_backoff(sv),0).
The
EXTENDand
MEXTENDmacros have been improved to avoid various issues with integer truncation and wrapping. In particular, some casts formerly used within the macros have been removed. This means for example that passing an unsigned
nitemsargument is likely to raise a compiler warning now (it's always been documented to require a signed value; formerly int, lately SSize_t).
PL_sawaliasand
GPf_ALIASED_SVhave been removed.
GvASSIGN_GENERATIONand
GvASSIGN_GENERATION_sethave been removed.
ISAglob to an array reference now properly adds
isaelemmagic to any existing elements. Previously modifying such an element would not update the ISA cache, so method calls would call the wrong function. Perl would also crash if the
ISAglob was destroyed, since new code added in 5.23.7 would try to release the
isaelemmagic from the elements. [perl #127351]]
qr/[[:alpha:]]/, but there was some slight defect in its specification which causes it to instead be treated as a regular bracketed character class. An example would be missing the second colon in the above like this:
qr/[[:alpha]]/. This compiles to match a sequence of two characters. The second is
"]", and the first is any of:
"[",
":",
"a",
"h",
"l", or
"p". This is unlikely to be the intended meaning, and now a warning is raised. No warning is raised unless the specification is very close to one of the 14 legal POSIX classes. (See "POSIX Character Classes" in perlrecharclass.) [perl #8904]]
A regression that allowed undeclared barewords in hash keys to work despite strictures has been fixed. [perl #126981]
Calls to the placeholder
&PL_sv_yesused internally when an
import()or
unimport()method isn't found now correctly handle scalar context. [perl #126042]
Report more context when we see an array where we expect to see an operator and avoid an assertion failure. [perl #123737]
Modifying an array that was previously a package
@ISAno longer causes assertion failures or crashes. [perl #123788]
Retain binary compatibility across plain and DEBUGGING perl builds. [perl #127212]
Avoid leaking memory when setting
$ENV{foo}on darwin. [perl #126240]
/...\G/no longer crashes on utf8 strings. When
\Gis a fixed number of characters from the start of the regex, perl needs to count back that many characters from the current
pos()position and start matching from there. However, it was counting back bytes rather than characters, which could lead to panics on utf8 strings.
In some cases operators that return integers would return negative integers as large positive integers. [perl #126635]
The
pipe()operator would assert for DEBUGGING builds]
FILE *or a
PerlIO *was
OUTPUT:ed or imported to Perl, since perl 5.000. These particular typemap entries are thought to be extremely rarely used by XS modules. [perl #124181]
alarm()and
sleep()will now warn if the argument is a negative number and return undef. Previously they would pass the negative value to the underlying C function which may have set up a timer with a surprising value..
qr/PAT
{min,max
}+
/is supposed to behave identically to
qr/(?>PAT
{min,max
})/. Since v5.20, this didn't work if min and max were equal. [perl #125825]
BEGIN <>no longer segfaults and properly produces an error message. [perl #125341]
Perl 5.24.0 represents approximately 11 months of development since Perl 5.22.0 and contains approximately 360,000 lines of changes across 1,800 files from 77 authors.
Excluding auto-generated files, documentation and release tools, there were approximately 250,000 lines of changes to 1,200 .pm, .t, .c and .h files.
Perl continues to flourish into its third decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.24.0:
Aaron Crane, Aaron Priven, Abigail, Achim Gratz, Alexander D'Archangel, Alex Vandiver, Andreas König, Andy Broad, Andy Dougherty, Aristotle Pagaltzis, Chase Whitener, Chas. Owens, Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan Collins, Daniel Dragan, David Golden, David Mitchell, Dominic Hargreaves, Doug Bell, Dr.Ruud, Ed Avis, Ed J, Father Chrysostomos, Herbert Breunung, H.Merijn Brand, Hugo van der Sanden, Ivan Pozdeev, James E Keenan, Jan Dubois, Jarkko Hietaniemi, Jerry D. Hedden, Jim Cromie, John Peacock, John SJ Anderson, Karen Etheridge, Karl Williamson, kmx, Leon Timmermans, Ludovic E. R. Tolhurst-Cleaver, Lukas Mai, Martijn Lievaart, Matthew Horsfall, Mattia Barbon, Max Maischein, Mohammed El-Afifi, Nicholas Clark, Nicolas R., Niko Tyni, Peter John Acklam, Peter Martini, Peter Rabbitson, Pip Cet, Rafael Garcia-Suarez, Reini Urban, Renee Baecker, Ricardo Signes, Sawyer X, Shlomi Fish, Sisyphus, Stanislaw Pusep, Steffen Müller, Stevan Little, Steve Hay, Sullivan Beck, Thomas Sibley, Todd Rinaldo, Tom Hukins, Tony Cook, Unicode Consortium, Victor Adam, Vincent Pit, Vladimir Timofeev, Yves Orton, Zachary Storer,.
SEE ALSO
The Changes file for an explanation of how to view exhaustive details on what changed.
The INSTALL file for how to build Perl.
The README file for general stuff.
The Artistic and Copying files for copyright information. | https://metacpan.org/pod/release/RJBS/perl-5.24.0/pod/perldelta.pod | CC-MAIN-2018-26 | refinedweb | 2,838 | 54.93 |
Launching From a Script
The recommended way to run PyMOL-Python scripts is by using PyMOL as the interpreter. This is supported by all versions of PyMOL, including the pre-compiled bundles provided by Schrödinger.
Example from a shell:
shell> pymol -cq script.py
With arguments (sys.argv becomes ["script.py", "foo", "bar"]):
shell> pymol -cq script.py -- foo bar
Example from a running PyMOL instance:
PyMOL> run script.py
For advanced users, Open-Source PyMOL (as well as the Schrödinger-provided "Mac alternative X11-only build") also allows to run PyMOL from an existing Python process. After importing the pymol module, PyMOL's event loop has to be started with a call to pymol.finish_launching().
Contents
Example 1
Here is an example script that launches PyMol for stereo viewing on a VisBox. It runs PyMol fullscreen stereo, and disables the internal gui. The environment (PYTHON_PATH and PYMOL_PATH) must already be set up for this example to work (see Example 2 below for how to setup within the script).
#!/usr/bin/env python # Tell PyMOL we don't want any GUI features. import __main__ __main__.pymol_argv = [ 'pymol', '-qei' ] # Importing the PyMOL module will create the window. import pymol # Call the function below before using any PyMOL modules. pymol.finish_launching() from pymol import cmd cmd.stereo('walleye') cmd.set('stereo_shift', 0.23) cmd.set('stereo_angle', 1.0)
Example 2
This script launches PyMOL without any GUI for scripting only. It enables tab-completion on the python command line and does the PyMOL environment setup (you need to adjust the moddir variable!). Hint: You may save this as "pymol-cli" executable.
#!/usr/bin/python2.6 -i import sys, os # autocompletion import readline import rlcompleter readline.parse_and_bind('tab: complete') # pymol environment moddir='/opt/pymol-svn/modules' sys.path.insert(0, moddir) os.environ['PYMOL_PATH'] = os.path.join(moddir, 'pymol/pymol_path') # pymol launching import pymol pymol.pymol_argv = ['pymol','-qc'] + sys.argv[1:] pymol.finish_launching() cmd = pymol.cmd
STDOUT
PyMOL captures sys.stdout and sys.stderr, to control it with it's own feedback mechanism. To prevent that, save and restore both streams, e.g.:
import sys stdout = sys.stdout stderr = sys.stderr pymol.finish_launching(['pymol', '-xiq']) sys.stdout = stdout sys.stderr = stderr | https://pymolwiki.org/index.php/Launching_From_a_Script | CC-MAIN-2017-04 | refinedweb | 368 | 53.88 |
Name: nt126004 Date: 06/03/2002 FULL PRODUCT VERSION : java version "1.3.1" Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.1-b24) Java HotSpot(TM) Client VM (build 1.3.1-b24, mixed mode) also java version "1.4.0" Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-b92) Java HotSpot(TM) Client VM (build 1.4.0-b92, mixed mode) Windows 2000 A DESCRIPTION OF THE PROBLEM : If you produce JAR using these two steps: 1. Create JAR from some files without adding manifest 2. Update JAR to include manifest If you use following code on jar-file produced this way getManifest() fails. File jarFile = new File("filename.jar"); inputStream = new FileInputStream(jarFile); jarInputStream = new JarInputStream(inputStream); Manifest manifest = jarInputStream.getManifest(); Reason seems to be that manifest is not the first file in the jar-file. There is allready a bug report (4263225) about this issue,it was marked "will not be fixed" state. Bug report states that "Secondly, the manifest file should always be the first entry in a particular jar file, in fact our jar tool enforces this restriction. Of course, we cannot prevent other vendors from manually putting the manifest at any other place in a jar, which is otherwise semantically equivalent.". As demonstrated incompabtible jar-file can be created also by using Sun's jar-tool. STEPS TO FOLLOW TO REPRODUCE THE PROBLEM : 1. Create JAR from some files without adding manifest 2. Update JAR to include manifest If you use following code on jar-file produced this way getManifest() fails. EXPECTED VERSUS ACTUAL BEHAVIOR : getManifest should not fail. -------------------- BEGIN SOURCE ----------------------- //compile.bat javac.exe *.java // pack.bat jar cvfM JarTest.jar *.java *.class jar umf Manifest.mf JarTest.jar // run.bat java.exe -classpath JarTest.jar JarTest // Manifest.mf // JarTest.java import java.util.jar.*; import java.io.*; public class JarTest { public static void main(String[] args) { try { File jarFile = new File("filename.jar"); InputStream inputStream = new FileInputStream(jarFile); JarInputStream jarInputStream = new JarInputStream(inputStream); Manifest manifest = jarInputStream.getManifest(); } catch (Exception e) { e.printStackTrace(); } } } --------------------- END SOURCE ------------------------ This bug can be reproduced always. (Review ID: 146951) ====================================================================== | https://bugs.java.com/bugdatabase/view_bug.do?bug_id=4696354 | CC-MAIN-2021-21 | refinedweb | 357 | 53.17 |
I was using Prisma in my Next.js app and I was doing it wrong.
I was initializing a new PrismaClient object in every page:
import { PrismaClient } from '@prisma/client' const prisma = new PrismaClient()
After some point, during app usage, I received the error
Already 10 Prisma Clients are actively running and also a
Address already in use.
To fix this, I exported this Prisma initialization to a separate file,
lib/prisma.js:
import { PrismaClient } from '@prisma/client' let prisma if (process.env.NODE_ENV === 'production') { prisma = new PrismaClient() } else { if (!global.prisma) { global.prisma = new PrismaClient() } prisma = global.prisma } export default prisma
The production check is done because in development,
npm run dev clears the Node.js cache at runtime, and this causes a new
PrismaClient initialization each time due to hot reloading, so we’d not solve the problem.
I took this code from
Finally I imported the exported
prisma object in my pages:
import prisma from 'lib/prisma'
Download my free Next.js Handbook! | https://flaviocopes.com/nextjs-fix-prismaclient-unable-run-browser/ | CC-MAIN-2022-27 | refinedweb | 166 | 56.05 |
47971/how-do-trim-the-leading-trailing-zeros-from-1d-array-in-python
Hey @Akki, you can use the numpy for this. You can use trim_zeros() function for this purpose.
>>> a = np.array((0, 0, 0, 1, 2, 3, 0, 2, 1, 0))
np.trim_zeros(a)
Hi, it is pretty simple, to be ...READ MORE
Hi @Mike. First, read both the csv ...READ MORE
For Python 3, try doing this:
import urllib.request, ...READ MORE
Hi, good question. If you are considering ...READ MORE
if you google it you can find. ...READ MORE
Syntax :
list. count(value)
Code:
colors = ['red', 'green', ...READ MORE
can you give an example using a ...READ MORE
You can simply the built-in function in ...READ MORE
Hey @Laksha, you can try something like ...READ MORE
lets say we have a list
mylist = ...READ MORE
OR | https://www.edureka.co/community/47971/how-do-trim-the-leading-trailing-zeros-from-1d-array-in-python?show=47973 | CC-MAIN-2019-39 | refinedweb | 141 | 89.55 |
#===========================================================================
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
Bug reports and comments to nik.ogura@gmail.com.
#===========================================================================
CGI::Lazy
use CGI::Lazy; our $q = CGI::Lazy->new({ tmplDir => "/path/to/templates", #not off doc root jsDir => "/js", #off doc root', }, }, }); print $q->header, $q->start_html({-style => {-src => '/css/style.css'}}), $q->javascript->modules(); print $q->template('topbanner2.tmpl')->process({ logo => '/images/funkyimage.png', mainTitle => 'Funktastic', secondaryTitle => $message, versionTitle => '0.0.1', messageTitle => 'w00t!', }); print $q->template('navbar1.tmpl')->process({ one => 'link one', one_link => '/blah.html', two => 'link two', two_link => '/blah.html', three => 'link three', three_link => '/blah.html', four => 'link four', four_link => '/blah.html', }); print $q->template('fileMonkeyHelp.tmpl')->process({helpMessage => 'help text here'}); print $q->template('fileMonkeyMain.tmpl')->process({mainmessage => "session info: <br> name: ".$q->session->data->name . "<br> time: ".$q->session->data->time}); print $q->template('footer1.tmpl')->process({version => $q->lazyversion}); with things that just about every modern website needs or wants, and to do it in a fairly portable manner.
There are plenty of webdev frameworks out there, many are far more full- featured. Often these solutions are so monstrous that they are overkill for small apps, or so optimized that they require full admin rights on the server they run on. CGI::Lazy was intended to be lightweight enough to run on any given server that could run perl cgi's. Of course, the more power you have, the fancier you will be able to get, so Lazy was written to be extensible and to (hopefully) play nice with whatever magic you have up your sleeve.
Lazy has also been written to be useful in a mod_perl environment if that is your pleasure. The wonders of persistence and namespaces have been (again, hopefully) all accounted for. It should plug into your mod_perl environment with little or no fuss.
For the most part, CGI::Lazy is simply a subclass of CGI::Pretty, which is an easier to read version of CGI.pm.
We need to use CGI::Pretty due to a css issue in IE where the style definitions aren't always followed unless there is the appropriate amount of whitespace between html tags. Luckilly, CGI::Pretty takes care of this pretty transparently, and its output is easier to read and debug.
CGI::Lazy adds a bunch of hooks in the interest of not working any harder than we need to, otherwise it's a CGI::Pretty object.
Probably 80% of the apps the author has been asked to write have been front ends to some sort of database, so that's definitely the angle Lazy is coming from. It works just fine with no db, but most of the fancy work is unavailable.
Output to the web is intended to be through templates via HTML::Template. However, if you want to write your content into the code manually, we won't stop you. Again, the whole point was to be flexible and reusable, and to spend our time writing new stuff, not the same old crap over and over again.
The CGI::Lazy::Widget::Dataset module especially was written to bring spreadsheet-like access to a database table to the web in a fairly transparent manner- after all, most of the time you're doing one of 4 operations on a database: select, insert, update, delete. The Dataset is, at least at the time of the original writing, the crown jewel of the Lazy framework. The templates for a Dataset are pretty complicated, and are tied pretty tightly to the Javascript that controls them on the client side. Because nobody (especially the author) wants to write these monsters from scratch every time a new Widget is called for, the CGI::Lazy::Template::Boilerplate class exists to generate boring, but functional templates for your Widgets. The boilerplate templates give you a functional starting place. After that, it's up to you.
In any event, it is my hope that this is useful to you. It has saved me quite alot of work. I hope that it can do the same for you. Bug reports and comments are always welcome.
Returns authentication object
Returns authorization object
Method retrieves CGI::Lazy::Config object for configuration variable retrieval See CGI::Lazy::Config for details
Method retrieves the database object CGI::Lazy::DB. The db object contains convenience methods for database access, and will contain the default database handle for the object.
Retrieves dbh from db object for use in cgi. Convenience method. Same as $q->db->dbh.
Returns the CGI::Lazy::ErrorHandler object. ErrorHandler contains convenience methods for trapping and returning error codes without generating a pesky 500 error.
Creates standard http header. Passes all arguments to CGI::Pretty::header, simply adding our own goodness to it in passing.
normal header args
returns CGI::Lazy::Javascript object.
see CGI::Lazy::Javascript for details.
Wraps javascript text in script tags and html comments for output to the browser. Pretty much the same as $q->script, but it comment wraps the script contents.
javascript text to output to the browser.
Returns mod_perl object if plugin is enabled.
See CGI::Lazy::ModPerl for details
Constructor. Creates the instance of the CGI::Lazy object.
If args is a hashref, it will assume that the hash is the config.
If it's just a string, it's assumed to be the absolute path to the config file for the Lazy object. That file will be parsed as JSON.
tmplDir => Directory where Lazy will look for html templates. Absolute path to directory. buildDir => Directory where Lazy will build template stubs. Absolute path to directory. jsDir => Directory where Lazy will look for javascript. Path relative to document root. cssDir => Directory where Lazy will look for css. Path relative to document root. noMinify => By default javascript is minified before output- all whitespace is removed. This speeds things up mightily, but can make for difficult debugging. Set this to a true value, and javascript will be printed with all whitespace intact. silent => Set to a true value, and internal errors will not be printed to STDERR. Defaults to false. plugins => Optional components mod_perl => mod_perl goodness dbh => Lazy handles database connection dbhVar => name of variable that holds database handle created elsewhere session => stateful sessions (requires database)
returns version of CGI::Lazy.
Returns plugin object.
see CGI::Lazy::Plugin for details.
Returns the session object see CGI::Lazy::Session for details.
Returns CGI::Lazy::Template object, or if it hasn't been created yet, creates it and returns it.
See CGI::Lazy::Template for details.
Returns CGI::Lazy::Utility object
See CGI::Lazy::Utility for details.
Returns hashref to the variables used in creating the object.
returns the CGI::Lazy::Widget object
Subversion repository available at:
A collection of demo scripts are available at: | http://search.cpan.org/~vayde/CGI-Lazy-1.08/lib/CGI/Lazy.pm | CC-MAIN-2015-40 | refinedweb | 1,135 | 58.99 |
November 2014
Volume 29 Number 11
Application Instrumentation : Application Analysis with Pin
Hadi Brais | November 2014
Program analysis is a fundamental step in the development process. It involves analyzing a program to determine how it will behave at run time. There are two types of program analysis: static and dynamic.
You’d perform a static analysis without running the target program, usually during source code compilation. Visual Studio provides a number of excellent tools for static analysis. Most modern compilers automatically perform static analysis to ensure the program honors the language’s semantic rules and to safely optimize the code. Although static analysis isn’t always accurate, its main benefit is pointing out potential problems with code before you run it, reducing the number of debugging sessions and saving precious time.
You’d perform a dynamic program analysis while running the target program. When the program ends, the dynamic analyzer produces a profile with behavioral information. In the Microsoft .NET Framework, the just-in-time (JIT) compiler performs dynamic analysis at run time to further optimize the code and ensures it won’t do anything that violates the type system.
The primary advantage of static analysis over dynamic analysis is it ensures 100 percent code coverage. To ensure such high code coverage with dynamic analysis, you usually need to run the program many times, each time with different input so the analysis takes different paths. The primary advantage of dynamic analysis is it can produce detailed and accurate information. When you develop and run a .NET application or secure C++ application, both kinds of analysis will be automatically performed under the hood to ensure that the code honors the rules of the framework.
The focus in this article will be on dynamic program analysis, also known as profiling. There are many ways to profile a program, such as using framework events, OS hooks and dynamic instrumentation. While Visual Studio provides a profiling framework, its dynamic instrumentation capabilities are currently limited. For all but the simplest dynamic instrumentation scenarios, you’ll need a more advanced framework. That’s where Pin comes into play.
What Is Pin?
Pin is a dynamic binary instrumentation framework developed by Intel Corp. that lets you build program analysis tools called Pintools for Windows and Linux platforms. You can use these tools to monitor and record the behavior of a program while it’s running. Then you can effectively evaluate many important aspects of the program such as its correctness, performance and security.
You can integrate the Pin framework with Microsoft Visual Studio to easily build and debug Pintools. In this article, I’ll show how to use Pin with Visual Studio to develop and debug a simple yet useful Pintool. The Pintool will detect critical memory issues such as memory leaking and double freeing allocated memory in a C/C++ program.
To better understand the nature of Pin, look at the complete definition term by term:
- A framework is a collection of code upon which you write a program. It typically includes a runtime component that partially controls program execution (such as startup and termination).
- Instrumentation is the process of analyzing a program by adding or modifying code—or both.
- Binary indicates the code being added or modified is machine code in binary form.
- Dynamic indicates the instrumentation processes are performed at run time, while the program is executing.
The complete phrase “dynamic binary instrumentation” is a mouthful, so people usually use the acronym DBI. Pin is a DBI framework.
You can use Pin on Windows (IA32 and Intel64), Linux (IA32 and Intel64), Mac OS X (IA32 and Intel64) and Android (IA32). Pin also supports the Intel Xeon Phi microprocessor for supercomputers. It not only supports Windows, but also seamlessly integrates with Visual Studio. You can write Pintools in Visual Studio and debug them with the Visual Studio Debugger. You can even develop debugging extensions for Pin to use seamlessly from Visual Studio.
Although Pin is proprietary software, you can download and use it free of charge for non-commercial use. Pin doesn’t yet support Visual Studio 2013, so I’ll use Visual Studio 2012. If you’ve installed both Visual Studio 2012 and 2013, you can create and open Visual Studio 2012 projects from 2013 and use the C++ libraries and tools of Visual Studio 2012 from 2013.
Download Pin from intel.ly/1ysiBs4. Besides the documentation and the binaries, Pin includes source code for a large collection of sample Pintools you’ll find in source/tools. From the MyPinTool folder, open the MyPinTool solution in Visual Studio.
Examine the project properties in detail to determine the proper Pintool configuration. All Pintools are DLL files. Therefore, the project Configuration Type should be set to Dynamic Library (.dll). You’ll also have to specify all headers, files, libraries and a number of preprocessor symbols required by the Pin header files. Set the entry point to Ptrace_DllMainCRTStartup%4012 to properly initialize the C runtime. Specify the /export:main switch to import the main function.
You can either use the properly configured MyPinTool project or create a new project and configure it yourself. You can also create a property sheet containing the required configuration details and import that into your Pintool project.
Pin Granularity
Pin lets you insert code into specific places in the program you’re instrumenting—typically just before or after executing a particular instruction or function. For example, you might want to record all dynamic memory allocations to detect memory leaks.
There are three main levels of granularity to Pin: routine, instruction and image. Pin also has one more not-so-obvious level—trace granularity. A trace is a straight-line instruction sequence with exactly one entry. It usually ends with an unconditional branch. A trace may include multiple exit points as long as they’re conditional. Examples of unconditional branches include calls, returns and unconditional jumps. Note that a trace has exactly one entry point. If Pin detected a branch to a location within a trace, it will end that trace at that location and start a new trace.
Pin offers these instrumentation granularities to help you choose the appropriate trade-off between performance and level of detail. Instrumenting at the instruction level might result in severe performance degradation, because there could be billions of instructions. On the other hand, instrumenting at the function level might be too general and, therefore, it might increase the complexity of the analysis code. Traces help you instrument without compromising performance or detail.
Write a Pintool
Now it’s time to write a useful Pintool. The purpose of this Pintool example is to detect memory deallocation problems common to C/C++ programs. The simple Pintool I’m going to write can diagnose an existing program without having to modify the source code or recompile it, because Pin performs its work at run time. Here are the problems the Pintool will detect:
- Memory leaks: Memory allocated, but not freed.
- Double freeing: Memory deallocated more than once.
- Freeing unallocated memory: Deallocating memory that hasn’t been allocated (such as calling free and passing NULL to it).
To simplify the code, I’ll assume the following:
- The main function of the program is called main. I won’t consider other variants.
- The only functions that allocate and free memory are new/malloc and delete/free, respectively. I won’t consider calloc and realloc, for example.
- The program consists of one executable file.
Once you understand the code, you can modify it and make the tool much more practical.
Define the Solution
To detect those memory problems, the Pintool must monitor calls to the allocation and deallocation functions. Because the new operator calls malloc internally, and the delete operator calls free internally, I can just monitor the calls to malloc and free.
Whenever the program calls malloc, I’ll record the returned address (either NULL or the address of the allocated memory region). Whenever it calls free, I’ll match the address of the memory being freed with my records. If it has been allocated but not freed, I’ll mark it as freed. However, if it has been allocated and freed, that would be an attempt to free it again, which indicates a problem. Finally, if there’s no record the memory being freed has been allocated, that would be an attempt to free unallocated memory. When the program terminates, I’ll again check records for those memory regions that have been allocated but not freed to detect memory leaks.
Choose a Granularity
Pin can instrument a program at four granularities: image, routine, trace and instruction. Which is best for this Pintool? While any of the granularities will do the job, I need to choose the one that incurs the least performance overhead. In this case, the image granularity would be the best. Once the image of the program is loaded, the Pintool can locate the malloc and free code within the image and insert the analysis code. This way, instrumentation overhead will be per-image instead of, for exmple, per-instruction.
To use the Pin API, I must include the pin.H header file in the code. The Pintool will be writing the results to a file, so I also have to include the fstream header file. I’ll use the map STL type to keep track of the memory being allocated and deallocated. This type is defined in the map header file. I’ll also use the cerr stream to show informative messages:
#include "pin.H" #include <iostream> #include <fstream> #include <map>
I will define three symbols to hold the names of the functions malloc, free and main:
#define MALLOC "malloc" #define FREE "free" #define MAIN "main"
These are the required global variables:
bool Record = false; map<ADDRINT, bool> MallocMap; ofstream OutFile; string ProgramImage; KNOB<string> OutFileName(KNOB_MODE_WRITEONCE, "Pintool", "o", "memtrace.txt", "Memory trace file name");
The Record variable indicates whether I’m inside the main function. The MallocMap variable holds the state of each allocated memory region. The ADDRINT type is defined by pin.H and represents a memory address. If the value associated with a memory address it TRUE, it has been deallocated.
The ProgramImage variable holds the name of the program image. The last variable is a KNOB. This represents a command-line switch to the Pintool. Pin makes it easy to define switches for a Pintool. For each switch, define a KNOB variable. The template type parameter string represents the type of the values that the switch will take. Here, the KNOB lets you specify the name of the output file of the Pintool through the “o” switch. The default value is memtrace.txt.
Next, I have to define the analysis routines executed at specific points in the code sequence. I need an analysis function, as defined in Figure 1, called just after malloc returns to record the address of the allocated memory. This function takes the address returned by malloc and returns nothing.
Figure 1 The RecordMalloc Analysis Routine Called Every Time Malloc Returns
VOID RecordMalloc(ADDRINT addr) { if (!Record) return; if (addr == NULL) { cerr << "Heap full!"; return; } map<ADDRINT, bool>::iterator it = MallocMap.find(addr); if (it != MallocMap.end()) { if (it->second) { // Allocating a previously allocated and freed memory. it->second = false; } else { // Malloc should not allocate memory that has // already been allocated but not freed. cerr << "Imposible!" << endl; } } else { // First time allocating at this address. MallocMap.insert(pair<ADDRINT, bool>(addr, false)); } }
This function will be called every time malloc is called. However, I’m only interested in the memory if it’s part of the instrumented program. So I’ll record the address only when Record is TRUE. If the address is NULL, I’ll just ignore it.
Then the function determines whether the address is already in MallocMap. If it is, then it must have been previously allocated and deallocated and, therefore, it’s now being reused. If the address isn’t in MallocMap, I’ll insert it with FALSE as the value indicating it hasn’t been freed.
I’ll define another analysis routine, shown in Figure 2, that I’ll have called just before free is called to record the address of the memory region being freed. Using MallocMap, I can easily detect if the memory being freed has already been freed or it hasn’t been allocated.
Figure 2 The RecordFree Analysis Routine
VOID RecordFree(ADDRINT addr) { if (!Record) return; map<ADDRINT, bool>::iterator it = MallocMap.find(addr); if (it != MallocMap.end()) { if (it->second) { // Double freeing. OutFile << "Object at address " << hex << addr << " has been freed more than once." << endl; } else { it->second = true; // Mark as freed. } } else { // Freeing unallocated memory. OutFile << "Freeing unallocated memory at " << hex << addr << "." << endl; } }
Next, I’ll need two more analysis routines to mark the execution and return of the main function:
VOID RecordMainBegin() { Record = true; } VOID RecordMainEnd() { Record = false; }
Analysis routines determine the code to instrument the program. I also have to tell Pin when to execute these routines. That’s the purpose of instrumentation routines. I defined an instrumentation routine as shown in Figure 3. This routine is called every time an image is loaded in the running process. When the program image is loaded, I’ll tell Pin to insert the analysis routines at the appropriate points.
Figure 3 The Image Instrumentation Routine
VOID Image(IMG img, VOID *v) { if (IMG_Name(img) == ProgramImage) { RTN mallocRtn = RTN_FindByName(img, MALLOC); if (mallocRtn.is_valid()) { RTN_Open(mallocRtn); RTN_InsertCall(mallocRtn, IPOINT_AFTER, (AFUNPTR)RecordMalloc, IARG_FUNCRET_EXITPOINT_VALUE, IARG_END); RTN_Close(mallocRtn); } RTN freeRtn = RTN_FindByName(img, FREE); if (freeRtn.is_valid()) { RTN_Open(freeRtn); RTN_InsertCall(freeRtn, IPOINT_BEFORE, (AFUNPTR)RecordFree, IARG_FUNCARG_ENTRYPOINT_VALUE, 0, IARG_END); RTN_Close(freeRtn); } RTN mainRtn = RTN_FindByName(img, MAIN); if (mainRtn.is_valid()) { RTN_Open(mainRtn); RTN_InsertCall(mainRtn, IPOINT_BEFORE, (AFUNPTR)RecordMainBegin, IARG_END); RTN_InsertCall(mainRtn, IPOINT_AFTER, (AFUNPTR)RecordMainEnd, IARG_END); RTN_Close(mainRtn); } } }
The IMG object represents the executable image. All Pin functions that operate at the image level start with IMG_*. For example, IMG_Name returns the name of the specified image. Similarly, all Pin functions that operate at the routine level start with RTN_*. For example, RTN_FindByName accepts an image and a C-style string and returns an RTN object representing the routine for which I’m looking. If the requested routine is defined in the image, the returned RTN object would be valid. Once I find the malloc, free and main routines, I can insert analysis routines at the appropriate points using the RTN_InsertCall function.
This function accepts three mandatory arguments followed by a variable number of arguments:
- The first is the routine I want to instrument.
- The second is an enumeration of type IPOINT that specifies where to insert the analysis routine.
- The third is the analysis routine to be inserted.
Then I can specify a list of arguments to be passed to the analysis routine. This list must be terminated by IARG_END. To pass the return value of the malloc function to the analysis routine, I’ll specify IARG_FUNCRET_EXITPOINT_VALUE. To pass the argument of the free function to the analysis routine, I’ll specify IARG_FUNCARG_ENTRYPOINT_VALUE followed by the index of the argument of the free function. All these values starting with IARG_* are defined by the IARG_TYPE enumeration. The call to RTN_InsertCall has to be wrapped by calls to RTN_Open and RTN_Close so the Pintool can insert the analysis routines.
Now that I’ve defined my analysis and instrumentation routines, I’ll have to define a finalization routine. This will be called upon termination of the instrumented program. It accepts two arguments, one being the code argument that holds the value returned from the main function of the program. The other will be discussed later. I’ve used a range-based for loop to make the code more readable:
VOID Fini(INT32 code, VOID *v) { for (pair<ADDRINT, bool> p : MallocMap) { if (!p.second) { // Unfreed memory. OutFile << "Memory at " << hex << p.first << " allocated but not freed." << endl; } } OutFile.close(); }
All I have to do in the finalization routine is to iterate over MallocMap and detect those allocations that haven’t been freed. The return from Fini marks the end of the instrumentation process.
The last part of the code is the main function of the Pintool. In the main function, PIN_Init is called to have Pin parse the command line to initialize the Knobs. Because I’m searching for functions using their names, PIN has to load the symbol table of the program image. I can do this by calling PIN_InitSymbols. The function IMG_AddInstrumentFunction registers the instrumentation function Image to be called every time an image is loaded.
Also, the finalization function is registered using PIN_AddFiniFunction. Note that the second argument to these functions is passed to the v parameter. I can use this parameter to pass any additional information to instrumentation functions. Finally, PIN_StartProgram is called to start the program I’m analyzing. This function actually never returns to the main function. Once it’s called, Pin takes over everything:
int main(int argc, char *argv[]) { PIN_Init(argc, argv); ProgramImage = argv[6]; // Assume that the image name is always at index 6. PIN_InitSymbols(); OutFile.open(OutFileName.Value().c_str()); IMG_AddInstrumentFunction(Image, NULL); PIN_AddFiniFunction(Fini, NULL); PIN_StartProgram(); return 0; }
Assembling all these pieces of code constitutes a fully functional Pintool.
Run the Pintool
You should be able to build this project without any errors. You’ll also need a program to test the Pintool. You can use the following test program:
#include <new> void foo(char* y) { int *x = (int*)malloc(4); } int main(int argc, char* argv[]) { free(NULL); foo(new char[10]); return 0; }
Clearly, this program is suffering from two memory leaks and one unnecessary call to free, indicating a problem with the program logic. Create another project that includes the test program. Build the project to produce an EXE file.
The final step to run the Pintool is to add Pin as an external tool to Visual Studio. From the Tools menu, select External tools. A dialog box will open as shown in Figure 4. Click the Add button to add a new external tool. The Title should be Pin and the Command should be the directory of the pin.exe file. The Arguments include the arguments to be passed to pin.exe. The -t switch specifies the Pintool directory. Specify the program to be instrumented after the two hyphens. Click OK and you should be able to run Pin from the Tools menu.
Figure 4 Add Pin to Visual Studio Using the External Tools Dialog Box
While running the program, the Output window will print anything you throw in the cerr and cout streams. The cerr stream usually prints informative messages from Pintool during execution. Once Pin terminates, you can view the results by opening the file the Pintool has created. By default, this is called memtrace.txt. When you open the file, you should see something like this:
Freeing unallocated memory at 0. Memory at 9e5108 allocated but not freed. Memory at 9e5120 allocated but not freed.
If you have more complex programs that adhere to the Pintool assumptions, you should instrument them using the Pintool, as you might find other memory issues of which you were unaware.
Debug the Pintool
When developing a Pintool, you’ll stumble through a number of bugs. You can seamlessly debug it with the Visual Studio Debugger by adding the -pause_tool switch. The value of this switch specifies the number of seconds Pin will wait before it actually runs the Pintool. This lets you attach the Visual Studio Debugger to the process running the Pintool (which is the same as the process running the instrumented program). Then you can debug your Pintool normally.
The Pintool I’ve developed here assumes the name of the image is at index 6 of the argv array. So if you want to add the pause-tool switch, the image name will be at index 8. You can automate this by writing a bit more code.
Wrapping Up
To further develop your skills, you can enhance the Pintool so it can detect other kinds of memory problems such as dangling pointers and wild pointers. Also, the Pintool output isn’t very useful because it doesn’t point out which part of the code is causing the problem. It would be nice to print the name of the variable causing the problem and the name of the function in which the variable is declared. This would help you easily locate and fix the bug in the source code. While printing function names is easy, printing variable names is more challenging because of the lack of support from Pin.
There are a lot of interactions happening between Pin, the Pintool and the instrumented program. It’s important to understand these interactions when developing advanced Pintools. For now, you should work through the examples provided with Pin to gain a better understanding of its power.
Hadi Brais is a Ph.D. scholar at the Indian Institute of Technology Delhi (IITD), researching optimizing compiler design technical expert for reviewing this article: Preeti Ranjan Panda | https://docs.microsoft.com/en-us/archive/msdn-magazine/2014/november/application-instrumentation-application-analysis-with-pin | CC-MAIN-2019-47 | refinedweb | 3,505 | 56.66 |
- .7 The .NET Framework Class Library
Many predefined classes are grouped into categories of related classes called namespaces. Together, these namespaces are referred to as the .NET Framework Class Library.
using Directives and Namespaces
Throughout the text, using directives allow us to use library classes from the Framework Class Library without specifying their namespace names. For example, an app would include the declaration
using System;
in order to use the class names from the System namespace without fully qualifying their names. This allows you to use the unqualified name Console, rather than the fully qualified name System.Console, in your code.
You might have noticed in each project containing multiple classes that in each class’s source-code file we did not need additional using directives to use the other classes in the project. There’s a special relationship between classes in a project—by default, such classes are in the same namespace and can be used by other classes in the project. Thus, a using declaration is not required when one class in a project uses another in the same project—such as when class AccountTest used class Account in Chapter 4’s examples. Also, any classes that are not explicitly placed in a namespace are implicitly placed in the so-called global namespace.
.NET Namespaces
A strength of C# is the large number of classes in the namespaces of the .NET Framework Class Library. Some key Framework Class Library namespaces are described in Fig. 7.4, which represents only a small portion of the reusable classes in the .NET Framework Class Library.
Fig. 7.4 | .NET Framework Class Library namespaces (a subset).
Locating Additional Information About a .NET Class’s Methods
You can locate additional information about a .NET class’s methods in the .NET Framework Class Library reference
When you visit this site, you’ll see an alphabetical listing of all the namespaces in the Framework Class Library. Locate the namespace and click its link to see an alphabetical listing of all its classes, with a brief description of each. Click a class’s link to see a more complete description of the class. Click the Methods link in the left-hand column to see a listing of the class’s methods. | http://www.informit.com/articles/article.aspx?p=2731935&seqNum=7 | CC-MAIN-2018-30 | refinedweb | 375 | 64.71 |
In my last post, I showed how the latest Apple TV system checks for an Apple-signed certificate before allowing changes to certain device settings. In particular, this prevents easily enabling the “Add Site” application, detailed in my 2013 DerbyCon talk. However, as I mentioned in the last post, it’s possible to load the profile on an Apple TV running 5.2 or 5.3, and then upgrade to 6.0, and retain access to Add Site. The problem then is that the system won’t actually permit adding any sites. What gives?
When adding a site (or channel or application or whatever you want to call it), the system first asks for a URL which points to a “vendor bag,” a .plist file defining the new application. Then it prompts for a site name, and then finally exits with the error “The site could not be verified for this device. Please check logs and retry.” Pulling the AppleTV binary into IDA Pro, we eventually find where the series of Add Site prompts occurs, in the method “[MEInternetTextEntryDialog _showNextPrompt]“.
This method is basically a 4-element finite state machine. When in state 0, it calls a method which prompts the user to enter the URL, and then changes the state to 1. In state 1, it asks for the new site’s name, then goes to state 2. In state 2, it sets up a call to “_verifySiteInfo”, then in state 3, it checks the result of that verification. If the response is good, it adds the site. If not, it shows the error and the user goes back to the beginning.
So what’s in “_verifySiteInfo”? That calls “[ATVAddSiteEntry entryWithName: andURL:]“, which calls “sub_186700”, which then calls “[ATVVendorBag isTrusted]“. If the response to the isTrusted call is zero, then the next pass through “_showNextPrompt” (in state 3) will display the error message and return to step 0.
So the actual check happens in the “[ATVVendorBag isTrusted]” method. Here’s the bulk of that routine, as disassembled by IDA Pro (and re-written manually to make it easier to follow):
result = 1; // // If /AppleInternal/Library/PreferenceBundles/Carrier Settings.bundle // exists, it's an internal build, and allow the site addition // if ( [[ATVSettingsFacade sharedInstance] runningAnInternalBuild]) return result; // // If the bag doesn't include icloud-auth-enabled, skip to next check // if (! [[self valueForKey:"icloud-auth-enabled"] boolValue]) { result = 1; goto LABEL_1; } // // The bag includes icloud-auth-enabled. Get and verify signature. // sig = [self valueForKey:"iCloudAuthSignature"]; text = [self merchantID]; text = [text stringByAppendingString:"iCloudAuth"]; // text will now be "<merchant id>iCloudAuth" text_utf8 = [text UTF8String]; text_len = strlen(text_utf8); // put the text to be signed into a byte array // and put the signature we pulled from the bag into an list of signatures text_bytes = [NSData dataWithBytes:text_utf8 length:text_len]; sig_array = [NSArray arrayWithObjects:sig count:1]; // now we take the text, and the list of signatures, and see if a sig matches result = sub_43C5D0(text, sig_array); // Here's where the fun happens if ( result == 1 ) // It passed the test -- the signature is valid { LABEL_1: if ( ! [[self valueForKey:"vendorBagLoadedByAddSite"] boolValue]) return result; // return 1 if: // * not added by Add Site AND // * not icloud-auth-enabled or // * is icloud-auth-enabled and signature matches // If we got here, then vendor bag was loaded by addSite // So we have to see if device is authorized text = [self merchantID]; text = [text stringByAppendingString: [ATVDevice uniqueID]]; // Now text is "<merchant id><device udid>" // And we do the same stuff as before with UTF8 strings, etc. text_utf8 = [text UTF8String]; text_len = strlen(text_utf8); text_bytes = [NSData dataWithBytes:text_utf8 length:text_len]; // Only this time the signatures are stored in the // com.apple.frontrow settings, likely loaded onto the device // via the profile that enabled Add Site to begin with. // And we may have more than one authorization (signature) to check. sig_array = [ATVSettingsFacade addSiteDeviceAuthorizations]; result = sub_43C5D0(text, sig_array); // test against all the signatures goto LABEL_2; } // if we got here, then iCloudAuthSignature failed result = 0; LABEL_2: if ( !result && _internalLogLevel >= 3 ) { _ATVLog(3, [self merchantID], @"Trust failure for merchant %@: %@"); result = 0; } return result;
This is all sort of complicated. Summarized, in pseudo-code:
If runningAnInternalBuild: Trusted If icloud-auth-enabled: If iCloudAuthSignature invalid: Not Trusted If vendorBagLoadedByAddSite: If device is authorized: Trusted Else: Not Trusted Else: Trusted
Basically, if the bag has an icloud-auth-signature, it better be valid, and if the bag was loaded by Add Site, then it the device has to be authorized for this particular merchant.
So, what is this elusive signature? We can find examples of icloud-auth-signature in the StoreFront call, mentioned in the last post:
<key>merchant</key> <string>iMovieNewAuth</string> <key>icloud-auth-enabled</key> <true/> <key>icloud-auth-signature</key> <data==</data>
This is the same format as similar signatures for javascript-url-signature and root-url-signature, and it validates in exactly the same way,with the same key. Interestingly, though, it doesn’t look like javascript-url and root-url signatures are actually checked in version 6.0! (Though it’s possible I made a mistake on that – I could find the checks in 5.2, but not in 6.0). The validation happens in the code above, at sub_43C5D0. This routine, paraphrased again, looks like this:
hash = CC_SHA1(text, len(text) key = SecKeyCreateRSAPublicKey(0, 13208544, 270, 1) for sig in signatures: if (! SecKeyRawVerify(key, 32770, hash, 20, sig, len(sig))): return 1 return 0
The 32770 above (in hex, 0x8002) is a constant that tells SecKeyRawVerify to expect a PKCS1SHA1 signature, which we can find in SecKey.h:
/* For SecKeyRawSign/SecKeyRawVerify only, data to be signed is a SHA1 hash; standard ASN.1 padding will be done, as well as PKCS1 padding of the underlying RSA operation. */ kSecPaddingPKCS1SHA1 = 0x8002,
Going to address 13208544, or 0xc98be0 in hex, and grabbing the next 270 bytes, gives us the public key. We can do that in IDA, or even with a simple python script:
$ python Python 2.7.5 (default, Aug 25 2013, 00:04:04) [GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.0.68)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> f=open("AppleTV", "r") >>> d=f.read() >>> o=0xc98be0 - 0x1000 # must subtract a memory offset >>>>> for i in range(0, 270): ... k += d[o+i] ... >>> import binascii >>> binascii.b2a_hex(k) '3082010a028201010090203010001' >>>
Write that out to a file (in binary form, not hexadecimal), and use asn1parse to get the raw key specifics:
$ openssl asn1parse -in rsakey.bin -inform DER 0:d=0 hl=4 l= 266 cons: SEQUENCE 4:d=1 hl=4 l= 257 prim: INTEGER 265:d=1 hl=2 l= 3 prim: INTEGER :010001
The long number is the modulus, and the short number is the exponent (65537).
So now we can validate the signature. For that, we could simply use some functions in the python Crypto module, but where would be the fun in that? Let’s just do it manually. In the following code, “message” is the string we want to verify, and “signature” is the signature (base-64 encoded) we pulled from StoreFront or a deviceAuthorizations setting.
from Crypto.Hash import SHA import binascii, base64 key = ' exponent = 65537 def manual_check(signature, message): sig = binascii.b2a_hex(base64.b64decode(signature)) h = SHA.new(message).hexdigest() print "Hash: %s" % h m = int(key, 16) ct = int(sig, 16) pt = pow(ct, exponent, m) out = "%x" % pt print "PT: %s" % out check = out[-40:] print "Check: %s" % check if check == h: print "VERIFIED" else: print " not verified" signature = ==' message = 'iMovieNewAuthiCloudAuth' manual_check(signature, message)
Running that code produces the following output:
Hash: 2dcd288c1ccc82c8ef7dcc17fdf3abd785c02050 PT: 1003021300906052b0e03021a0 50004142dcd288c1ccc82c8ef7dcc17fdf3abd785c02050 Check: 2dcd288c1ccc82c8ef7dcc17fdf3abd785c02050 VERIFIED
The plaintext (“PT” above) is a DER-format signature, matching the requirements for PKCS1-v1.5. Basically, it’s:
0x00 (not seen) 0x01 (leading 0 not seen) 0xff (times "a lot") (pad the message to a pre-determined length) 0x00 (end of padding) sig (actual signature in DER format)
The actual signature includes flags identifying it as SHA-1 based, and the actual message that was signed (the SHA1 hash). We can simply ignore everything except the 20 bytes at the end, which looks exactly like the hash we generated (2dcd288…c02050). Or if you like, we can use asn1parse again, or an online DER parser to break it all out:
SEQUENCE(2 elem) SEQUENCE(2 elem) OBJECT IDENTIFIER 1.3.14.3.2.26 NULL OCTET STRING(20 byte) 2DCD288C1CCC82C8EF7DCC17FDF3ABD785C02050
(Where 1.3.14.3.2.26 corresponds to the OID for SHA-1.)
This same signature check is used for all the above-mentioned signatures:
- javascript-url-signature
- root-url-signature
- icloud-auth-signature
- addSiteDeviceAuthorizations
As I said earlier, I’m not sure the first two are being checked any longer. The third seems to be included on few of the newer applications loaded by the StoreFront call, while the last is only checked if a vendor bag is loaded by Add Site.
The signatures for the last check are stored as an array in the com.apple.frontrow “addSiteDeviceAuthorizations” setting. And, as we saw last time, the only way to add a stting to that list is with a profile signed by Apple. So the only way to make Add Site work under Apple TV 6.x (ignoring any unfortunately-still-speculative jailbreaks) is to:
- Retrieve the target Apple TV’s unique device identifier (udid)
- Using your app’s Merchant ID, create the string “<merchant><udid>”
- Get Apple to sign that string with the appropriate private key
- Include that signature in a configuration profile that enables the Add Site application
- Get Apple to sign the profile
- Install the profile on the Apple TV from step 1
Then, and only then, will you be able to load your custom application on the Apple TV.
All this leaves me with a question: “Why did Apple add all these hoops to jump through?” It’s basically a parallel to how Provisioning Profiles work for iOS developers. Was this extra level of security really necessary? As far as I know, the Add Site functionality wasn’t widely known until my talk last fall, yet these changes appeared in early iOS 7-based Apple TV betas in mid-summer 2013. Perhaps they were always on the roadmap, and Apple just couldn’t finish them in time for the previous version.
Or perhaps…is this a prelude to wider availablity of Apple TV app development? If devlopers to build Apple TV apps, and to distribute them via a new “Channel Store.” Maybe this will even be unveiled with the next major Apple TV update (currently rumored for April).
I’m keeping my fingers crossed. | https://darthnull.org/security/2014/02/21/atv-rsa-sigs/ | CC-MAIN-2018-51 | refinedweb | 1,773 | 51.68 |
Make XML Native and Relative
By Jonathan Gennick
Oracle XML DB provides native format and relational database access.
XML is fast becoming the language of choice for data interchange between businesses. However, most businesses store their data in relational databases such as Oracle9i Database. So how do you bridge the gap between the hierarchical, document-centric world of XML and the tabular, set-oriented world of relational databases? Do you store your XML documents as files on a file system? Do you shred, pull your XML documents apart, and store the data relationally? Choosing between these two approaches involves weighing the trade-offs based on how you use the data. But what if you didn't have to choose? What if you could take both approaches simultaneously? You can, using a new Oracle9i Database Release 2 feature known as the XML DB Repository.
The Repository Explained
Oracle XML DB is neither a separate product nor a separate option that you must install. Oracle XML DB refers to the collection of XML features and technologies built directly into Oracle9i Database. A key feature is the XML DB Repository. This repository enables you to store XML documents directly in Oracle9i Database Release 2. Once your XML documents are in the repository, you can access your XML data in either an XML-centric or a relational-centric manner.
To store XML data in your database, you simply write an XML document file using FTP, HTTP, or WebDAVall industry-standard protocols. Getting XML data out of your database can be as simple as executing a SQL query or reading a file using one of those same protocols.
Setting the Scene
Imagine that you're in the business of marketing CDs produced by independent artists. You need to exchange information with the major music-store chains, online sites, and the artists themselves. You've just developed the XML document format shown in Listing 1 for describing the contents of a CD, and now you want to leverage the XML DB Repository to store that information in your database. You want easy access to the data from SQL and easy access to the native XML documents. In short, you want the data to be relational and hierarchical. In this article, I'm your DBA, and it's my job to make that happen.
Registering the XML Schema
My first step is to register your XML schema with the XML DB Repository. When I register an XML schema, the repository creates object types and object tables capable of holding instances of that schema. The following call to dbms_xmlschema.registerURI, which I execute from SQL*Plus, retrieves the XML schema shown in Listing 2 from and registers it:
BEGIN
dbms_xmlschema.registerURI(
'cd.xsd',
'');
END;
/
Note: In addition to CREATE privileges for all the various schema object types, I also need ALTER SESSION and QUERY REWRITE privileges in order to register a schema and create the examples in this article.
Listing 3 shows some of the structures and objects created as a result of registering the CD schema. An XML table named CD331_TAB was created to hold instances of the schema: each CD document in the repository will be represented by one row in this table. I can get a list of such XML tables by querying
the USER_XML_TABLES data dictionary
view. In this case, I simply queried the view before and after registering the schema and looked for the new table name. Each row in CD331_TAB will
contain one instance of type CD327_T, which was created to correspond to our XML schema. The top-level fields in our XML document are represented as attributes of the CD327_T type, and the attribute names match the XML field names. For example, the Title field in the object
type corresponds directly to the Title element in the XML schema. The Songs field corresponds to the Songs element. Songs is a complex element in the XML schema, and as such it's mapped to yet another object type, "Songs328_T". If I issued the SQL*Plus command DESCRIBE "Songs328_T" and continued to drill down into the definition of the Songs field, I'd see that the collection of songs was ultimately implemented as a VARRAY in which each element represented one song.
I can control the object and type names that Oracle9i Database generates when I register a schema; I can also control the specific datatypes used to store my XML data. I do this by annotating the XML schema, using attributes defined by XML DB Repository and part of the oraxdb namespace. Oracle9i Database generates these attributes for me when I don't supply them, and I can easily view what Oracle9i Database generates by looking at the version of the schema stored in the repository. Figure 1 illustrates how conveniently you can access repository data, this time via HTTP, using a standard Web browser. Figure 1 shows part of the CD schema in my repository, and you can see the schema annotations, which are all prefaced by "oraxdb". Note that the URL refers to port 8080, which is the default HTTP port used by the repository.
By default, all objects created when registering a schema will be owned by the user registering the schema. In this case, I own the table and type in Listing 3 and all the other types associated with the CD schema. Because I've registered the schema, any XML files I save to the repository that are instances of the CD schema will be shredded and stored in the CD331_TAB table. The schema and registration are specific to me. CD files saved
by other users will not be stored in my
table. You do have the option, using an
optional parameter to dbms_xmlschema.register Schema, to create a global schema that affects all users, so that any user can save a CD document to the table.
Creating an XML Folder
If I'm going to store CD XML documents in the XML DB Repository, I need a folder in which to put them. To create one, I log in as the SYSTEM user and execute the PL/SQL block found in Listing 4. The call to dbms_xdb.createfolder creates a top-level folder named /CD. The PL/SQL block then uses the dbms_xdb.setAcl procedure to create an access control list (ACL) granting all folder privileges to the owner, which is SYSTEM, and read privileges to all other users. The next step is to issue an UPDATE statement against the repository's RESOURCE_VIEW in order to change ownership of the folder from SYSTEM to GENNICK. It's important to commit after creating a folder; it won't be visible to other sessions until you do. I can now connect as GENNICK using FTP or WebDAV and deposit XML files into the /CD folder.
Saving an XML Document
Once I register the schema and create a folder to hold my XML documents, saving a document to the repository is
as easy as copying a file. Listing 5
shows an FTP session that copies the file LegendsOfTheGreatLakes.xml, shown in Listing 1, to the repository. Port 2100, used in the FTP open command, is the default port used by the repository for FTP sessions. Note that rather than use FTP, I could just as easily have used Windows Copy & Paste, using WebDAV and a Windows Web folder.
Using the RESOURCE_VIEW
An important view that you should be aware of is the view named RESOURCE_VIEW. The RESOURCE_VIEW returns one row for each document or folder in the repository to which you have access. For example, you can get a list of all XML documents under the /CD folder by executing the query shown here:
SELECT any_path
FROM resource_view
WHERE under_path(res,'/CD')=1
AND extractValue(res,
'/Resource/ContentType')='text/xml';
ANY_PATH
-------------------------------
/CD/Gospel/NothingLess.xml
/CD/LegendsOfTheGreatLakes.xml
The new UNDER_PATH function shown above allows you to test whether a given repository resource falls somewhere under a folder (or path) that you specify. In this case, my use of the function restricts query results to resources in the /CD folder and subfolders under /CD. Path-based queries against RESOURCE_VIEW are made efficient by a hierarchical domain index created on the underlying table. This index is part of the repository; you don't need to create it.
The RES column in the resource view does not represent the resource itself, but only the metadata for the resource. Applying the new extractValue function to the RES column examines the content type of each resource. Thus the query results are further restricted to paths pointing to XML documents. The '/Resource/ContentType' syntax represents XPath notation. XPath is a standard notation for specifying parts of an XML document; you'll use it a lot in queries against XML data.
Given a repository path, you can use the new XDBUriType object type to retrieve all or part of the underlying XML document. Listing 6 shows two queries. The first query is an extension to that shown above, adding the use of XDBUriType to retrieve all XML documents under the /CD folder. The second query in Listing 6 is a further refinement that appends standard XPath syntax to the end of the URL in order to extract just the CD titles.
Relational Access to Repository Data
It's also possible to access XML data in the repository by going straight to the underlying table. The underlying table that I created when I registered the CD schema is CD331_TAB. You can write queries directly against this table, but those queries must be XML-aware. To facilitate access to XML data from reporting tools designed for use with relational data, you can create a view such as the one shown in Listing 7. In addition to a view, Listing 7 also creates an index on artist name. The view and index allow me to efficiently execute standard relational queries such as the following:
SELECT title
FROM cd_master
WHERE artist='Carl Behrend';
Updating XML Data
Unfortunately, because all the columns in the cd_master view are based on SQL functions, the view is not updateable. However, it is possible to update XML data in the repository; I just need to update the underlying table created when the schema was registered, as in the following:
UPDATE CD331_TAB cd
SET VALUE(cd) = updateXML(
value(cd),
'/CD/Website/text()',
'
legends.htm');
Note the use of XPath syntax in this new updateXML function. The path '/CD/Website/text()' specifies that I want to update the text in the CD document's Website field. My third argument to updateXML specifies the new value for that text. This is an in-place update, making it a very efficient operation. XML DB Repository does not need to reconstruct the entire XML document being changed. Because the schema is registered, XML DB Repository is able to rewrite this query in such a way that only the Website attribute in the underlying object structure is touched.
Where Next?
With the XML DB Repository, you can store XML documents in the database and access those documents using standard internet protocols. At the same time, you can access the same XML documents, or just parts of those documents, using standard relational queries. You don't have XML data and relational data; you just have data, period. "XML" and "relational" are merely different paradigms for looking at your data. By separating data from paradigm, Oracle9i protects one of your most important assetsyour datafrom the shifting winds of paradigm changes.
Jonathan Gennick (Jonathan@Gennick.com) is an experienced Oracle DBA and an Oracle Certified Professional. He currently makes his living as a writer and recently completed work on the Oracle SQL*Plus Pocket Reference, Second Edition (O'Reilly & Associates, 2002). | http://www.oracle.com/technology/oramag/oracle/03-jan/o13xml.html | crawl-002 | refinedweb | 1,958 | 52.7 |
Hi Andy, > - Why does an ESDC have a session timeout in 20 minutes, yet the cookie > lifespan can be 30 days. Surely there will be no way to tie a cookie back up > to a session since the ESDC will be have had that person nuked, I was sort > of hoping I coudl persist the data in the ESDC for a long time to provide > storage (I could always set the minutes to 99999 or something silly). I > guess if I really want data to be persisted for ever some sort of Membership > product will be needed... A session data object timeout of "0" as set in the session data container means "give me completely persistent session data objects, do not expire them". Set it to this, and set a high cookie timeout. But yes, a better way to do something like this is to use sessioning in combination with a membership product. > - Mounting a non-undoable db into Zope is not trivial unless there is > something Im missing. There's a non-undoable system every Zope installation > has called the file system, why dont we use that? I was thinking we could > modifiy LocalFS to provide that sort of functionality would be much > easier... Local filesystem access won't work across ZEO clients. The primary purpose of an external data container is to provide access to a shared namespace between ZEO clients. This doesn't mean someone couldn't write an alternate data container implementation that uses the filesystem, however. As far as the difficulty of mounting goes, when I can find some time, I want to write a mounting howto. HTH, - C _______________________________________________ Zope-Dev maillist - [EMAIL PROTECTED] ** No cross posts or HTML encoding! ** (Related lists - )
- [Zope-dev] CoreSessionTracking stuff Andy McKay
- Re: [Zope-dev] CoreSessionTracking stuff Chris McDonough
- Re: [Zope-dev] CoreSessionTracking stuff Andy McKay | https://www.mail-archive.com/zope-dev@zope.org/msg04438.html | CC-MAIN-2016-44 | refinedweb | 308 | 59.74 |
Recently I've been asked many times how SolidJS is so much faster than all their favourite libraries. They get the basics and have heard the rhetoric before but don't understand how Solid is any different. I'm going to try my best to explain it. It is a bit heavy at times. It's ok if it takes a couple of sittings. There is a lot here.
People talk a lot about Reactivity and the cost of the Virtual DOM, yet the libraries they use have all the same trappings. From template renders that are still effectively a top-down diff, to reactive libraries that still feed into the same old Component system. Is it any wonder that we still hit the same performance plateau?
Now to be clear there is a reason we hit the same performance plateau in the browser. The DOM. Ultimately that is our biggest limitation. It's the law of physics we much obey. So much that I've seen people use some of the cleverest algorithms and still stare puzzled at the performance improving an intangible amount. And that's because ironically the best way to attack something like is being scrappy. Taking points where they count and leaving other things on the table.
Arguably one of the fastest standalone DOM diffs right now udomdiff came about this way. @webreflection was on twitter asking if anyone knew a faster DOM diffing algorithm after growing tired of tweaking academic algorithms and not making headway. I pointed him to @localvoid(author of ivi) algorithm that was being used is most of the top libraries and he was like it looks a bunch of optimizations for a particular benchmark. To which I replied sure, but these are also all the most common ways people manipulate a list, and you will find hold up in almost all benchmarks. The next morning he had come back with his new library taking an almost too simple Set lookup combined with these techniques. And guess what it was smaller and about the same performance. Maybe even better.
I like this story because that has been my experience in this area. It wasn't smart algorithms but understanding what was important and then just a bit of hard work.
The Reactive Model
I use a variation of that algorithm now in Solid but ironically even this raw diffing implementation is less performant in the JS Framework Benchmark than Solid's non-precompiled approach. In fact, when talking about simple Tagged Template Literal libraries Solid's approach is faster than lit-html, uhtml or any of the libraries that pioneered this approach. Why is that?
Ok, I assume at least some of you have drunk the Svelte Kool-Aid and are ready to go "It's Reactive". And it's true, but Svelte is slower than all the libraries I've mentioned so far so it's not quite that. Vue is reactive too and it still manages to offset any performance benefits by feeding it right back into a VDOM. The real answer is there is no single answer. It's a combination of many small things but let's start with the reactive system.
Solid's Reactive system looks like a weird hybrid between React Hooks, and Vue 3's Composition API. It predates them both but it did borrow a few things from Hooks in terms of API:
const [count, setCount] = createSignal(1); createEffect(() => { console.log(count()); // 1 }); setCount(2); // 2
The basics come down to 2 primitives. A reactive atom, that I call a Signal, and a Computation(also known as a derivation) that tracks its change. In this case, creating a side effect (there is also
createMemo that stores a computed value). This is the core of fine-grained reactivity. I've covered how this works previously, so today we are going to build on it to see how we can make a whole system out of it.
The first thing you have to realize is these are just primitives. Potentially powerful primitives, very simple primitives. You can do pretty much whatever you want with them. Consider:
import { render, diff, patch } from "v-doms-r-us"; import App from "./app" const [state, setState] = createSignal({ name: "John" }), mountEl = document.getElementById("app"); let prevVDOM = []; createEffect(() => { const vdom = render(<App state={state()} />); const patches = diff(vdom, prevVDOM); patch(mountEl, patches); prevVDOM = vdom; }); setState({ name: "Jake" });
It's the same example again except now the side effect is to create a VDOM tree, diff it against the previous version, and patch the real DOM with it. Pretty much the basics of how any VDOM library works. By simply accessing state in the effect like count above we re-run every time it updates.
So reactivity is a way of modelling a problem, not really any particular solution. If using diffing is advantageous go for it. If creating 1000 independent cells that update independently is to our advantage we can do that too.
Thinking Granular
The first thing that probably comes to mind is what if instead of having a single computation and diffing a tree on update what if we just updated only what has changed. This is by no means a new idea. But takes some consideration to wrestle the tradeoffs. Creating many subscriptions as you walk the DOM is actually more expensive than say rendering a Virtual DOM. Sure it is quick to update but most updates are relatively cheap compared to the cost of creation regardless of the approach you take. Solving for granularity is all about mitigating unnecessary costs at creation time. So how can we do that?
1. Use a compiler
Libraries spend a decent amount of time deciding what to do when creating/updating. Generally, we iterate over attributes, children parsing the data to decide how to properly do what's needed. With a compiler, you can remove this iteration and decision tree and simply just write the exact instructions that need to happen. Simple but effective.
const HelloMessage = props => <div>Hello {props.name}</div>; // becomes const _tmpl$ = template(`<div>Hello </div>`); const HelloMessage = props => { const _el$ = _tmpl$.cloneNode(true); insert(_el$, () => props.name, null); return _el$; };
Solid's tagged template literal version does almost the same with just-in-time compilation at runtime and still is remarkably fast. But the HyperScript version is slower than some of the faster Virtual DOM libraries simply from the overhead of doing this work even once. If you aren't compiling with Reactive library, a top-down library is doing the same traversal as you just not constructing all the subscriptions. It's going to be more performant at creation. Mind you a top-down approach, like a VDOM, won't bother compiling generally since it has to run the creation path anyway on an update as it constantly re-creates the VDOM. It gains more advantage from memoization.
2. Clone DOM Nodes
Yep. Surprisingly few non-Tagged Template libraries do this. It makes sense since if your view is composed of a bunch of function calls like the VDOM you don't get the chance to look at it holistically. What is more surprising is most compiled libraries don't do this either. They create each element one at a time. This is slower than cloning a template. The larger the template more effective it is. But you see really nice gains here when you have lists and tables. Too bad there aren't many of those on the Web. 😄
3. Loosen the granularity
What? Make it less granular? Sure. Where are we paying the highest cost on update? Nesting. Doing unnecessary work reconciling lists by far. Now you might be asking why even reconcile lists at all? Same reason. Sure a row swap would be much faster with direct updates. However, when you consider batching updates and that order matters it isn't that simple to solve. It's possible there will be progress here but in my experience currently list diffing is better for the general problem. That being said you don't want to be doing this all time.
But where is the highest creation cost? Creating all those computations. So what if we only made one for each template to handle all attributes as a mini diff, but still create separate ones for inserts. It's a good balance since the cost of diffing a few values to be assigned to attributes costs very little, but saving 3 or 4 computations per row in a list is significant. By wrapping inserts independently we still keep from doing unnecessary work on update.
4. Use less computations
Yes obviously. More specifically how do we encourage the developer to use less. It starts with embracing the reactive mentality of everything that can be derived should be derived. But nothing says we need to make this any more complicated than my first example. Maybe you've seen a version of this example before when learning about fine-grained reactivity.
const [user, setUser] = createState({ firstName: "Jo", lastName: "Momma" }); const fullName = createMemo(() => `${user.firstName} ${user.lastName}`); return <div>Hello {fullName}</div>;
Awesome we've derived
fullName and it updates independently whenever
firstName or
lastName updates. It's all automatic and powerful. Maybe your version called it a
computed or maybe wanted you to use
$: label. Did you ever ask yourself the value of creating that computation here? What if we just(notice we removed
createMemo):
const [user, setUser] = createState({ firstName: "Jo", lastName: "Momma" }); const fullName = () => `${user.firstName} ${user.lastName}`; return <div>Hello {fullName}</div>;
You guessed it. Effectively the same thing and we have one less computation. Now a computation means we don't re-create the string
fullName unless
firstName or
lastName change but unless used elsewhere in another computation that has other dependencies it won't run again anyway. And even so, is creating that string that expensive? No.
So the key to remember with Solid is it doesn't need to be a signal or computed you are binding. As long as that function at some point wraps a signal or state access you will be tracking it. We don't need a bunch of computations in the middle unless we are trying to cache values. No hangups around
state.value or
boxed.get. It's always the same a function call whether directly on a signal, masked behind a proxy, or wrapped in 6 levels of function transformations.
5. Optimize reactivity for creation
I studied a lot of different reactive libraries the crux of their bottlenecks around creation came down to the data-structures they use to manage their subscriptions. Signals hold the list of subscribers so that they can notify them when they update. The problem is that the way computations reset subscriptions on each run, requires them to remove themselves from all their observed signals. That means keeping a list on both sides. Where on the signal side where we iterate on update this is pretty simple, on the computation side we need to do a lookup to handle that removal. Similarly to prevent duplicate subscriptions we'd need to do a lookup every time we access a signal. Naive approaches in the past used arrays and
indexOf searches which are painfully slow along with
splice to remove the entry. More recently we've seen libraries use Sets. This is generally better but sets are expensive at creation time. The solution interestingly enough was to use 2 arrays on each side, one to hold the item, and one to hold the reverse index on its counterpart, and at creation time don't initialize them. Only create them as needed. We can avoid
indexOf lookups and instead of
splice we can just replace the node at the removed index with the item at the end of the list. Because of push/pull evaluation and the concept of execution clock we can still ensure in order updates. But what we've done is prevent immature memory allocations and remove lengthy lookups on initial creation.
Reactive Components
We have come to love the adaptability that comes from the modularity of Components. But not all Components are equal. In a Virtual DOM library, they are little more than an abstraction for a type of VDOM node. Something that can serve as an ancestor for its own tree and but ultimately a link in the data structure. In reactive libraries, they have served a slightly different role.
The classic problem with the observer pattern (the one used by these libraries) is handling the disposal of subscriptions no longer needed. If that which is observed outlives the computation(observer) tracking it, the observed still holds a reference in its subscription list to the observer and tries to call it on updates. One way to solve it is to manage the whole cycle using Components. They provide a defined boundary for managing lifecycle and as mentioned previously you don't take much of a hit for loosening granularity. Svelte uses this approach and takes it a step further not even maintaining a subscription list and just having any update trigger the update portion of the generated code.
But there is a problem here. The lifecycle of reactivity is fully bound here, fully localized. How do we communicate values out reactively? Essentially synchronization through that computation. We resolve values only to wrap them all over again. This super common pattern in reactive libraries and infinitely more costly than its Virtual DOM counterpart. This approach will always hit a performance wall. So let's "get rid of it".
The Reactive Graph
This is the only thing that needs to be there. What if we piggyback off of it? This graph is comprised of signals and computations linked together through subscriptions. Signals can have multiple subscriptions and computations can subscribe to multiple signals. Some computations like
createMemo can have subscriptions themselves. So far a graph is the wrong term here as there is no guarantee all nodes are connected. We just have these groupings of reactive nodes and subscriptions that look something like this:
But how does this compose? If nothing was dynamic this would be most of the story. However, if there is conditional rendering or loops somewhere effectively you will:
createEffect(() => show() && insert(parentEl, <Component />))
The first thing you should notice is that Component is being created under another computation. And it will be creating its own computations underneath. This works because we push the reactive context on to a stack and only the immediate computation tracks. This nesting happens throughout the view code. In fact, other than top-level all computations are created under other computations. As we know from our reactive basics, whenever a computation re-evaluates it releases all subscriptions and executes again. We also know stranded computations cannot release themselves. The solution is just to have the computations register with their parent computation and for clean up the same way we do subscriptions whenever that parent re-evaluates. So if we wrap the top level with a root computation (something inert, not tracking) then we get automatic disposal for our whole reactive system without introducing any new constructs.
Components?
As you can see we don't really need Components to do anything to manage lifecycles. A Component will always exist as long as the computation that houses it does, so tying into that computations disposal cycle is as effective as having its own method. In Solid, we register
onCleanup methods that can work in any computation whether it's to release an event handler, stop a timer, or cancel an asynchronous request. Since initial render or any reactive triggered update executes from within a computation you can place these methods anywhere to cleanup at the granularity that is needed. In summary, a Component in Solid is just a function call.
If a Component is just a function call then how does it maintain its own state? The same way functions do. Closures. It isn't the closure of a single component function. It's the closures in each computation wrapper. Each
createEffect or binding in your JSX. At runtime Solid has no concept of Component. As it turns out this is incredibly lightweight and efficient. You are only paying for the cost of setting up the reactive nodes, no other overhead.
The only other consideration is how do you handle reactive props if there is nothing to bind them to. The answer there is simple too. Wrap them in a function like we did in #4 above. The compiler can see that a prop could be dynamic and just wraps it in a function, and then using a simple object getter provides a unified props object API for the Component to use. No matter where the underlying signal is coming from and passed down through all the components in a render tree we only need a computation at the very end where it is being used to update the DOM or be part of some user computation. Because we need dependency access to be in the consuming computation all props are lazily evaluated, including children.
This is a very powerful pattern for composition as it is an inversion of control as the deepest leaves control the access, while the render tree composes the behavior. It's also incredibly efficient as there is no intermediary. We effectively flatten the subscription graph maintaining the granularity we desire on updates.
Conclusion
So in summary, SolidJS' performance comes from appropriately scaled granularity through compilation, the most effective DOM creation methods, a reactive system not limited to local optimization and optimized for creation, and an API that does not require unnecessary reactive wrappers. But what I want you to think about is, how many of those are actually architectural rather than implementation details? A decent number. Most performant non-VDOM libraries do portions of these things but not all. And it would not be easy for them to do so. Like React's move to React Fiber has not been as easy for other VDOM libraries to replicate. Can Svelte the way it is written now disappear Components along with the Framework? Probably not. Can lit-html reactively handle nested updates as effectively? Unlikely.
So yes there is a lot of content here. And I feel like I've shared a lot of my secrets. Although to be fair, it's already out there in the source code. I'm still learning stuff every day and I expect this to continue to evolve. All these decisions come with tradeoffs. However, this is the way that I've put together what I believe to be the most effective way to render the DOM.
solidjs
/
solid
A declarative, efficient, and flexible JavaScript library for building user interfaces.
Website • API Docs • Features Tutorial • Playground • Discord
Solid is a declarative JavaScript library for creating user interfaces. Instead of using a Virtual DOM, it compiles its templates to real DOM nodes and updates them with fine-grained reactions. Declare your state and use it throughout your app, and when a piece of state changes, only the code that depends on it will rerun. Check out our intro video or read on!
Key Features
- Fine-grained updates to the real DOM
- Declarative data: model your state as a system with reactive primitives
- Render-once mental model: your components are regular JavaScript functions that run once to set up your view
- Automatic dependency tracking: accessing your reactive state subscribes to it
- Small and fast
- Simple: learn a few powerful concepts that can be reused, combined, and built on top of
- Provides modern framework features like JSX, fragments, Context, Portals, Suspense, streaming…
Discussion (3)
Absolutely brilliant. I was thinking about something similar but I was missing the array on the counterpart. Thanks for the idea!
Hi Ryan, you are clearly a JavaScript master. Thanks for the write-up and It is good that you're setting the performance bar so high.
Thank you for writing a response. I acknowledge the content here gets pretty deep. I'm still figuring out how to best explain this stuff without getting so detailed. I've put this off for a long time as I felt even if people asked the question they don't "really" want to know. But I just felt the need to get it all out there for start. Each section here could probably be its own article (albeit I think pretty boring ones without seeing the big picture), but its something. | https://dev.to/ryansolid/thinking-granular-how-is-solidjs-so-performant-4g37 | CC-MAIN-2022-33 | refinedweb | 3,423 | 64.41 |
Literate programming with python doctests
Posted May 17, 2018 at 04:41 PM | categories: noweb, orgmode, python | tags: | View Comments
Updated May 18, 2018 at 03:07 PM
Table of Contents
On the org-mode mailing list we had a nice discussion about using noweb and org-mode in literate programming. The results of that discussion were blogged about here. I thought of a different application of this for making doctests in Python functions. I have to confess I have never liked these because I have always thought they were a pain to write since you basically have to put code and results into a docstring. The ideas developed in the discussion above led me to think of a new way to write these that seems totally reasonable.
The idea is just to put noweb placeholders in the function docstring for the doctests. The placeholders will be expanded when you tangle the file, and they will get their contents from other src-blocks where you have written and run examples to test them.
This video might make the rest of this post easier to follow:
I will illustrate the idea using org-mode and the ob-ipython I have in scimax. The defaults of my ob-ipython setup are not useful for this example because it puts the execution count and mime types of output in the output. These are not observed in a REPL, and so we turn this off by setting these variables.
(setq ob-ipython-suppress-execution-count t ob-ipython-show-mime-types nil)
Now, we make an example function that takes a single argument and returns one divided by that argument. This block is runnable, and the function is then defined in the jupyter kernel. The docstring contains several noweb references to doctest blocks we define later. For now, they don't do anything. See The noweb doctest block section for the block that is used to expand these. This block also has a tangle header which indicates the file to tangle the results to. When I run this block, it is sent to a Jupyter kernel and saved in memory for use in subsequent blocks.
Here is the block with no noweb expansion. Note that this is easier to read in the original org source than it is to read in the published blog format.
def func(a): """A function to divide one by a. <<doctest("doctest-1")>> <<doctest("doctest-2")>> <<doctest("doctest-3")>> Returns: 1 / a. """ return 1 / a
Now, we can write a series of named blocks that define various tests we might want to use as doctests. You can run these blocks here, and verify they are correct. Later, when we tangle the document, these will be incorporated into the tangled file in the docstring we defined above.
func(5) == 0.2
True
This next test will raise an Exception, and we just run it to make sure it does.
func(0)
ZeroDivisionErrorTraceback (most recent call last) <ipython-input-6-ba0cd5a88f0a> in <module>() ----> 1 func(0) <ipython-input-1-eafd354a3163> in func(a) 18 Returns: 1 / a. 19 """ ---> 20 return 1 / a ZeroDivisionError: division by zero
This is just a doctest with indentation to show how it is used.
for i in range(1, 4): print(func(i))
1.0 0.5 0.3333333333333333
That concludes the examples I want incorporated into the doctests. Each one of these blocks has a name, which is used as an argument to the noweb references in the function docstring.
1 Add a way to run the tests
This is a common idiom to enable easy running of the doctests. This will get tangled out to the file.
if __name__ == "__main__": import doctest doctest.testmod()
2 Tangle the file
So far, the Python code we have written only exists in the org-file, and in memory. Tangling is the extraction of the code into a code file.
We run this command, which extracts the code blocks marked for tangling, and expands the noweb references in them.
(org-babel-tangle)
Here is what we get:
def func(a): """A function to divide one by a. >>> func(5) == 0.2 True >>> func(0) Traceback (most recent call last): ZeroDivisionError: division by zero >>> for i in range(1, 4): ... print(func(i)) 1.0 0.5 0.3333333333333333 Returns: 1 / a. """ return 1 / a if __name__ == "__main__": import doctest doctest.testmod()
That looks like a reasonable python file. You can see the doctest blocks have been inserted into the docstring, as desired. The proof of course is that we can run these doctests, and use the python module. We show that next.
3 Run the tests
Now, we can check if the tests pass in a fresh run (i.e. not using the version stored in the jupyter kernel.) The standard way to run the doctests is like this:
python test.py -v
Well, that's it! It worked fine. Now we have a python file we can import and reuse, with some doctests that show how it works. For example, here it is in a small Python script.
from test import func print(func(3))
0.3333333333333333
There are surely some caveats to keep in mind here. This was just a simple proof of concept idea that isn't tested beyond this example. I don't know how many complexities would arise from more complex doctests. But, it seems like a good idea to continue pursuing if you like using doctests, and like using org-mode and interactive/literate programming techniques.
It is definitely an interesting way to use noweb to build up better code files in my opinion.
4 The noweb doctest block
These blocks are used in the noweb expansions. Each block takes a variable which is the name of a block. This block grabs the body of the named src block and formats it as if it was in a REPL.
We also grab the results of the named block and format it for the doctest. We use a heuristic to detect Tracebacks and modify the output to be consistent with it. In that case we assume the relevant Traceback is on the last line.
Admittedly, this does some fragile feeling things, like trimming whitespace here and there to remove blank lines, and quoting quotes (which was not actually used in this example), and removing the ": " pieces of ob-ipython results. Probably other ways of running the src-blocks would not be that suitable for this.
(org-babel-goto-named-src-block name) (let* ((src (s-trim-right (org-element-property :value (org-element-context)))) (src-lines (split-string src "\n")) body result) (setq body (s-trim-right (s-concat ">>> " (car src-lines) "\n" (s-join "\n" (mapcar (lambda (s) (concat "... " s)) (cdr src-lines)))))) ;; now the results (org-babel-goto-named-result name) (let ((result (org-element-context))) (setq result (thread-last (buffer-substring (org-element-property :contents-begin result) (org-element-property :contents-end result)) (s-trim) ;; remove ": " from beginning of lines (replace-regexp-in-string "^: *" "") ;; quote quotes (replace-regexp-in-string "\\\"" "\\\\\""))) (when (string-match "Traceback" result) (setq result (format "Traceback (most recent call last):\n%s" (car (last (split-string result "\n")))))) (concat body "\n" result)))
Copyright (C) 2018 by John Kitchin. See the License for information about copying.
Org-mode version = 9.1.13 | http://kitchingroup.cheme.cmu.edu/blog/category/noweb/ | CC-MAIN-2020-05 | refinedweb | 1,224 | 72.05 |
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LoPy Nano-Gateway
**NOTE: THIS EXAMPLE HAS BEEN UPDATED AND I RECOMMEND USING THE NEW CODE THAT CONTAINS SEVERAL IMPROVEMENTS
GO TO
Here are some code samples to put the LoPy in nano-gateway mode. This is just a code demo and you will need to change it to meet your needs.
For this demo we are connecting 2 LoPys (nodes) to 1 LoPy in Nano-Gateway mode
nano_gateway.py
import socket import struct from network import LoRa # A basic package header, B: 1 byte for the deviceId, B: 1 byte for the pkg size, %ds: Formated string for string _LORA_PKG_FORMAT = "!BB%ds" # A basic ack package, B: 1 byte for the deviceId, B: 1 bytes for the pkg size, B: 1 byte for the Ok (200) or error messages _LORA_PKG_ACK_FORMAT = "BBB" # Open a LoRa Socket, use rx_iq to avoid listening to our own messages lora = LoRa(mode=LoRa.LORA, rx_iq=True) lora_sock = socket.socket(socket.AF_LORA, socket.SOCK_RAW) lora_sock.setblocking(False) while (True): recv_pkg = lora_sock.recv(512) if (len(recv_pkg) > 2): recv_pkg_len = recv_pkg[1] device_id, pkg_len, msg = struct.unpack(_LORA_PKG_FORMAT % recv_pkg_len, recv_pkg) # If the uart = machine.UART(0, 115200) and os.dupterm(uart) are set in the boot.py this print should appear in the serial port print('Device: %d - Pkg: %s' % (device_id, msg)) ack_pkg = struct.pack(_LORA_PKG_ACK_FORMAT, device_id, 1, 200) lora_sock.send(ack_pkg)
The _LORA_PKG_FORMAT is used to have a way of identifying the different devices in our network
The _LORA_PKG_ACK_FORMAT is a simple ack package as response to the nodes package
node_1.py
import os import socket import time import struct from network import LoRa # A basic package header, B: 1 byte for the deviceId, B: 1 bytes for the pkg size _LORA_PKG_FORMAT = "!BB%ds" _LORA_PKG_ACK_FORMAT = "BBB" DEVICE_ID = 0x01 # Open a Lora Socket, use tx_iq to avoid listening to our own messages lora = LoRa(mode=LoRa.LORA, tx_iq=True) lora_sock = socket.socket(socket.AF_LORA, socket.SOCK_RAW) lora_sock.setblocking(False) while(True): # Package send containing a simple string msg = "Device 1 Here" pkg = struct.pack(_LORA_PKG_FORMAT % len(msg), DEVICE_ID, len(msg), msg) lora_sock.send(pkg) # Wait for the response from the gateway. NOTE: For this demo the device does an infinite loop for while waiting the response. Introduce a max_time_waiting for you application)
The node is always sending packages and waiting for the ack from the gateway.
To adapt this code to your needs you might:
- Put a max waiting time for the ack to arrive and resend the package or mark it as invalid
- Increase the package size changing the _LORA_PKG_FORMAT to "BH%ds" the H will allow to keep 2 bytes for size (for more information about struct format go here)
- Reduce the package size with bitwise manipulation
- Reduce the message size (for this demo a string) to something more useful for you development
@colateral Hi, i am using 1 gateway that only with pymaker opened while the node i using the power bank to power up. I have try both in vice versa yet no result showing out.
Hi there, i am still new to lopy. I have try the example of the Lora.nanogateway code () with only 1 lopy as gateway and 1 lopy as node. There is no response between both of them after i have coded it. What happen to this? Thank you.
Hi @Roberto I tried to modify your code because I need to send a payload that contains the current time with a header containing mac address of the node and the length of the payload. Everything went well on the node side but rated nano gateway I have an Index Error: bytes index out of rang. it is because the adresse mac ? knowing that lora.mac() give : b'p\xb3\xd5I\x95kA\xf3' with length=8 but i don't understand what does mean the : b'p......' and how the length is 8 !!
thanks
node
# LoRa node SRC_ADR_MAC=lora.mac() #compteur packets PACKETs_Cnt=5 while(PACKETs_Cnt>0): # Package send containing a simple string msg=time.time() msg_len=len(str(msg)) pkg = struct.pack('!%dsBi' % len(SRC_ADR_MAC), SRC_ADR_MAC, msg_len, msg) lora_sock.send(pkg) PACKETs_Cnt=PACKETs_Cnt-1 time.sleep(5)
nano GW
# LoRa GW while (True): recv_pkg = lora_sock.recv(255) if (len(recv_pkg) > 2): device_adr_mac, msg_len, msg = struct.unpack('!%dsBi' %8 , recv_pkg) # %8 because len(lora.mac())=8 print('Device: %s - Pkg: %s' % (device_adr_mac, msg)) time.sleep(5)
@assia said in LoPy Nano-Gateway:
@Colateral said in LoPy Nano-Gateway:
Hi @Roberto i am bbegginer in LoRa and i don't understand the use of rx_iq and tx_iq.!
It's easy. A LoRaWAN network is not a peer to peer network. There is a master (the gateway) that communicates with the nodes, but there is no node to node communication.
Imagine that one of your nodes has the receiver active and another one transmits. The transmission is intended to be received by the gateway, of course (we said that there is no node-to-node communication) but the receiving node will get the packet anyway, if only to discard it.
That reception and discarding has an energy cost. How do you avoid it? By having the nodes transmit in a mode that a node can't understand, only the gateway.
Now, imagine this scenario: you make the nodes use tx_iq inversion (which is a sort of signal inversion) and the gateway use rx_iq inversion.
In this case, a signal transmitted by a node will be inverted, and the gateway will successfully decode it. But other nodes, expecting a non inverted signal, won't detect the inverted signal. So you have just avoided the unintended packet reception problem.
@Colateral said in LoPy Nano-Gateway:
Hi @Roberto i am bbegginer in LoRa and i don't understand the use of rx_iq and tx_iq.!
thanks
@Colateral
Thanks for the quick response, i'll try a blocking approach to see if i can reproduce the error and check whats the root of it.
@Roberto HI Roberto. Thanks. I ran the last script and is running fine. Regarding the memory leak, I believe is related with socket blocking approach. If we change the script and move to non blocking (as your script does) everything works fine.
Hi @Colateral
As i wrote in my last message, there is a new example of the nano-gateway with a non-blocking loop approach.
Regarding the memory issues we will look into this. I left the code on the other post running for 3 hours without any problems. I will leave it running today on a test bench for 24+ h to see if there are any problems and monitor the memory while it transmits. Will let you know the results.
The link to the new code is
@Roberto Your example it is a good start but looping and blocking might not be a good approach.
We built another script that is using threads with blocking socket ... and run the script on a minimal Lora "star" network: one GW and 2 NODES. For each device you have to configure tx,rx and device id in cfg file . and upload the script and cfg file on it and run the script in Putty (not Pymakr). We didn't faced with this script clashing issues.. but we faced other issues.
You will see that after awhile on GW, the script is ending with a memory leak... but this is never happening on the nodes.
If you run the script from 3 Pymakr instances ... sometimes is working for hours and after that the GW is stop sending.
We conclude that is something wrong on the stack.
The issue might be related only to rx_iq configuration.
@Roberto I have successfully got a 2 node and 1 gateway setup working based on your code, thanks very much. One minor query, In the gateway you use
_LORA_PKG_FORMAT = "!BB%ds"
but in the node_1.py you miss off the
!, e.g.
_LORA_PKG_FORMAT = "BB%ds"
Shouldn't they be consistent?
Hi @Colateral,
Yes, i have noticed that sometimes some messages arrive malformed or with bytes missing. This could be due to LoRa message collision between devices. If two devices send at the same time in the same band this can happen.
There is a new blog here in the forum with a new code suggestion that includes.
- Message length check on the nano-gateway
- Message retry on the nodes
- Max timeout in the nodes
Number 3 will help with the fact that you have to have the nano-gateway on before you start the nodes. In this code, after sending a message the node waits in an infinite loop for the ack. The problem with this approach is that if no ack is received (the nano-gateway was not connected yet) the node will stay in that loop until reseted.
Keep in ming that both this and the new code are just examples for specific usages and they require adaptation depending on your needs.
The link for the new post is LoPy Nano-Gateway Extended (Timeout and Retry)
Best,
Roberto
@Roberto We setup a test bench with 3 LoPy following the idea of your code. We did the test with blocking socket and thread and non blocking sockets. The result is the same.
2 are the nodes configured as tx_iq and and one is the Gw (rx_iq).
The script is simple: each device (node and GW) is sending 29 bytes message size (_MSG_FORMAT = "!HHLBB%ds") each 2 seconds. In the msg data we are printing a counter (that varies from device). That counter is also in the header (see above)
We noticed that sometimes if you start the gw after the nodes... randomly some of the nodes are not receiving the data, despite the fact the GW is receiving the data from the nodes. And we observed also that sometimes when we start the node after the GW, the GW is not receiving the data from the nodes.
You need to reset the node or GW in order to get the broadcasted data from to the others... and this hazardous and not at all good in real deployment.
BUT THE MOST PROBLEMATIC is the fact that the 29bytes are partially received, sometimes you are getting 15bytes or whatever number less than 29bytes.
Have you experience this connection issue related with nodes/gw starting order?
Does LoPy stack is guarantee the receiving of msg in one chunk? ( if you send 29bytes you got 29bytes)
Here are some samples:
good msg receive
from: 800
to: 0
Id: 3058
Flags: 0
PayloadSize: 18
Payload: b'3058- 1234567890 '
<<< beat msgId 3066
bufferSize 29
pkgSize 28
data_size 18
remaining buffer 0
bad msg receive
from: 800
to: 0
Id: 3059
Flags: 0
PayloadSize: 18
Payload: b'3059- 1234567890 '
bufferSize 15
buffer too small <<< ustruct exception
- FelixDonkers last edited by
@gertjanvanhethof I'm also interrested to use LoPy as a LoRaWan gateway. Looking forward to a solution.
This post is deleted!
- microman7k last edited by
Hi,
On "Nano-Gateway" with the latest firmware 1.3.0.b1 i'm still getting "ValueError: buffer too small" after hour of two running posted sample code. Is this problem with the sample code or is it firmware problem? | https://forum.pycom.io/topic/236/lopy-nano-gateway/5 | CC-MAIN-2020-24 | refinedweb | 1,861 | 64.51 |
- Type:
Bug
- Status: Open
- Resolution: Unresolved
- Affects Version/s: 1.8
- Fix Version/s: None
- Component/s: SVG Viewer
- Labels:None
- Environment:Operating System: Windows Vista
Platform: PC
While participating in a batik-users thread [1], I discovered a set of (minor?) issues while playing with Batik Squiggle's DOM Viewer. I'm creating this bug in order to 1) act as a reminder to try better tracking them down whenever possible and 2) act like a list of known-issues in case someone else also happens to bump at something weird while using the DOM viewer.
Maybe this could/should be broken into several bugs (one per issue) but, given that these issues should be fairly to fix, managing multiple issues can become too much of a burden (as already discussed a couple of times in batik-dev).
1. Works with simple cases [1], seem to choke with more complex ones [2].
Nevertheless, in the second test case, I'm also seeing unresolved namespace weirdness (the "a0" hints towards that)which I thought it had already been fixed in trunk:
<a0:g xmlns:
<a0:path
</a0:g>
I still haven't figured out if this is due to:
- [3] being a more complex document;
- [3] making heavy use of cubic splines, which may be breaking the node finder/highlighting algorithm.
2. The DOM viewer doesn't maintain state: whenever the (DOM Viewer) window is closed and opened again, the previously highlighted items are disconnected. The simplest approach would be clearing the set of highlighted items prior to closing the window; another possibility would be maintaining state, for example by hiding the window instead of closing it (not sure about the performance implications of that).
Both issues were noticed in revision 892855, using Sun Java 1.6 update 17 on Windows Vista SP2.
[1]
[2]
[3] | https://issues.apache.org/jira/browse/BATIK-932 | CC-MAIN-2020-45 | refinedweb | 306 | 55.78 |
> After studying the working draft and much > experimentation, I am not able to get xsl:namespace to create a > namespace node in the result document using Xalan Java 2.6.0 or Xalan > Java 2.2.Dll. That's because Xalan doesn't implement XSLT 2.0. I would expect it to give you an error message when you use the xsl:namespace instruction. > > <xsl:template > <xsl:copy-of > <xsl:element > <!-- I expect to see a xmlns:test='...' in the > resulting xsl:stylesheet tag --> > <xsl:namespace > <xsl:apply-templates /> > </xsl:element> > </xsl:template> > > You mentioned that I would need to also use the > xsl:namespace-alias. Can > you explain more on this as I am not able to find any reference to how > xsl:namespace and xsl:namespace-alias work together? They don't work together. As I think I said, xsl:namespace-alias only affects the results of literal result elements. > For example, the following: > > <xsl:stylesheet > xmlns: xmlns: xmlns: xmlns: > > <xsl:namespace-alias > <xsl:template > <xsl:copy-of > <cxsl:stylesheet> > <xsl:namespace > <xsl:apply-templates /> > </cxsl:stylesheet> > </xsl:template> > </xsl:stylesheet> > > 1) The above copied all namespaces to the result document even though > I'm not using xmlns:test. > Why did xmlns:test show up? cxsl:stylesheet is a literal result element. When an LRE is evaluated, all its in-scope namespaces (other than those listed in exclude-result-prefixes) are copied to the result tree. > And why does the xsl:element not have the same behavior? Because that's the way it's specified. > > 2) I expected to see xmlns:google='...' in the cxsl:stylesheet node in > the result document. Of course, it is not there. > I'm wondering why? > My only surprise here is that Xalan doesn't error on this stylesheet. The rule is that an XSLT 1.0 processor, given a stylesheet that says version="2.0", should give a run-time error if you try to execute an instruction in the XSLT namespace that hasn't been defined in the XSLT 1.0 specification, unless it has an xsl:fallback child element. Michael Kay | https://www.oxygenxml.com/archives/xsl-list/200501/msg00377.html | CC-MAIN-2020-40 | refinedweb | 351 | 68.16 |
Foundations
The Data on the Web Best Practices, which became a Recommendation in January this year, forms the foundation. As I highlighted at the time, it sets out the steps anyone should take when sharing data on the Web, whether openly or not, encouraging the sharing of actual information, not just information about where a dataset can be downloaded. A domain-specific extension, the Spatial Data on the Web Best Practices, is now all-but complete. There again, the emphasis is on making data available directly on the Web so that, for example, search engines can make use of it directly and not just point to a landing page from where a dataset can be downloaded – what I call using the Web as a glorified USB stick.
Spatial Data
That specialized best practice document is just one output from the Spatial Data on the Web WG in which we have collaborated with our sister standards body, the Open Geospatial Consortium, to create joint standards. Plans are being laid for a long term continuation of that relationship which has exciting possibilities in VR/AR, Web of Things, Building Information Models, Earth Observations, and a best practices document looking at statistical data.
Research Data
Another area in which I very much hope W3C will work closely with others is in research data: life sciences, astronomy, oceanography, geology, crystallography and many more ‘ologies.’ Supported by the VRE4EIC project, the Dataset Exchange WG was born largely from this area and is leading to exciting conversations with organizations including the Research Data Alliance, CODATA, and even the UN. This is in addition to, not a replacement for, the interests of governments in the sharing of data. Both communities are strongly represented in the DXWG that will, if it fulfills its charter, make big improvements in interoperability across different domains and communities.
Linked Data
The use of Linked Data continues to grow; if we accept the Gartner Hype Cycle as a model then I believe that, following the Trough of Disillusionment, we are well onto the Slope of Enlightenment. I see it used particularly in environmental and life sciences, government master data and cultural heritage. That is, it’s used extensively as a means of sharing and consuming data across departments and disciplines. However, it would be silly to suggest that the majority of Web Developers are building their applications on SPARQL endpoints. Furthermore, it is true that if you make a full SPARQL endpoint available openly, then it’s relatively easy to write a query that will be so computationally expensive as to bring the system down. That’s why the BBC, OpenPHACTS and others don’t make their SPARQL endpoints publicly available. Would you make your SQL interface openly available? Instead, they provide a simple API that runs straightforward queries in the background that a developer never sees. In the case of the BBC, even their API is not public, but it powers a lot of the content on their Web site.
The upside of this approach is that through those APIs it’s easy to access high value, integrated data as developer-friendly JSON objects that are readily dealt with. From a publisher’s point of view, the API is more stable and reliable. The irritating downside is that people don’t see and therefore don’t recognize the Linked Data infrastructure behind the API allowing the continued questioning of the value of the technology.
Semantic Web, AI and Machine Learning
The main Semantic Web specs were updated at the beginning of 2014 and there are no plans to review the core RDF and OWL specs any time soon. However, that doesn’t mean that there aren’t still things to do.
One spec that might get an update soon is JSON-LD. The relevant Community Group has continued to develop the spec since it was formally published as a Rec and would now like to put those new specs through Rec Track. Meanwhile, the Shapes Constraint Language. SHACL, has been through something of a difficult journey but is now at Proposed Rec, attracting significant interest and implementation.
But, what I hear from the community is that the most pressing ‘next thing’ for the Semantic Web should be what I call ‘annotated triples.’ RDF is pretty bad at describing and reflecting change: someone changes job, a concert ticket is no longer valid, the global average temperature is now y not x and so on. Furthermore, not all ‘facts’ are asserted with equal confidence. Natural Language Processing, for example, might recognize a ‘fact’ within a text with only 75% certainty.
It’s perfectly possible to express these now using Named Graphs, however, in talks I’ve done recently where I’ve mentioned this, including to the team behind Amazon’s Alexa, there has been strong support for the idea of a syntax that would allow each tuple to be extended with ‘validFrom’, validTo and ‘probability’. Other possible annotations might relate to privacy, provenance and more. Such annotations may be semantically equivalent to creating and annotating a named graph, and RDF 1.1 goes a long way in this direction, but I’ve received a good deal of anecdotal evidence that a simple syntax might be a lot easier to process. This is very relevant to areas like AI, deep learning and statistical analysis.
These sorts of topics were discussed at ESWC recently and I very much hope that there will be a W3C workshop on it next year, perhaps leading to a new WG. A project proposal was submitted to the European Commission recently that would support this, and others interested in the topic should get in touch.
Other possible future work in the Semantic Web includes a common vocabulary for sharing the results of data analysis, natural language processing etc. The Natural Language Interchange Format, for example, could readily be put through Rec Track.
Vocabularies and schema.org
Common vocabularies, maintained by the communities they serve, are an essential part of interoperability. Whether it’s researchers, governments or businesses, better and easier maintenance of vocabularies and a more uniform approach to sharing mappings, crosswalks and linksets, must be a priority. Internally at least, we have recognized for years that W3C needs to be better at this. What’s not so widely known is that we can do a lot now. Community Groups are a great way to get a bunch of people together and work on your new schema and, if you want it, you can even have a namespace (either directly or via a redirect). Again, subject to an EU project proposal being funded, there should be money available to improve our tooling in this regard.
W3C will continue to support the development of schema.org which is transforming the amount of structured data embedded within Web pages. If you want to develop an extension for schema.org, a Community Group and a discussion on public-vocabs@w3.org is the place to start.
Summary
To summarize, my personal priorities for W3C in relation to data are:
- Continue and deepen the relationship with OGC for better interoperability between the Web and geospatial information systems.
- Develop a similarly deep relationship with the research data community.
- Explore the notion of annotating RDF triples for context, such as temporal and probabilistic factors.
- Be better at supporting vocabulary development and their agile maintenance.
- Continue to promote the Linked Data/Semantic Web approach to data integration that can sit behind high value and robust JSON-returning APIs.
I’ll be watching …
One thought on “Possible future directions for data on the Web”
Thanks for summarizing the information, very useful. | https://www.w3.org/blog/2017/06/possible-future-directions-for-data-on-the-web/ | CC-MAIN-2018-09 | refinedweb | 1,272 | 50.16 |
I wrote a VB program years ago. In an effort to learn a Java, I have rewritten it in Java. I have archival data that i would like to convert, so I can read it in my Java program.
I have been researching datatype representations to figure out some conversions, but have run into a brick wall mainly due to my newness to Java and time away from VB.
I have a field in VB that is single and is 69.7 (represented internally as x'66668A42'. For the life of me, I cannot figure out this internal representation. However, how do I convert this to something that Java can understand (double)?
0x66668A42 is the little endian representation of the float value 69.2
Its presumably little endian because thats the native x86 format. In contrast java defines everything as big endian, even if the underlying platform is not.
So to convert your VB single to a java float you have to shuffle the bytes into reverse order, then convert the int to float:
public class L2BFloat { public static void main(String[] argv) { int x = 0x66668A42; System.out.println(little2Big2Float(x)); } public static float little2Big2Float(int little) { // int endian conversion int big = (little & 0x000000FF) << 24 | (little & 0x0000FF00) << 8 | (little & 0x00FF0000) >>> 8 | (little & 0xFF000000) >>> 24; // convert to float return Float.intBitsToFloat(big); } } | https://codedump.io/share/zY7GRwtmUeEU/1/visual-basic-single-data-type-in-java | CC-MAIN-2016-44 | refinedweb | 221 | 63.49 |
Subject: [Boost-bugs] [Boost C++ Libraries] #10530: Attempting to define own lexical cast on solaris has to use deprected method
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2014-09-23 13:48:18
Keywords: |
-------------------------------------+--------------------------
In version 1.41 of boost, it was possible to do (eg this)
namespace boost
{
template <> bool lexical_cast(std::string const &s) { ... };
}
In 1.55 this stopped working on sun workshop compiler (Studio 12, version
5.12) saying 'can't find definition in namespace'.
I've had to revert to the deprecated pass-by-value declaration but I can't
find any documentation that indicates that this is necessary or why it
might have changed.
-- Ticket URL: <> Boost C++ Libraries <> Boost provides free peer-reviewed portable C++ source libraries.
This archive was generated by hypermail 2.1.7 : 2017-02-16 18:50:17 UTC | https://lists.boost.org/boost-bugs/2014/09/38034.php | CC-MAIN-2022-27 | refinedweb | 139 | 56.76 |
The point of this thread is to be a comprehensive summary of the available javascript libraries - but with a twist.
Most threads I've seen thus far with regards to libraries are:
Inevitably, responses to these threads are short "jQuery rulz" or "Prototype is too big" or "You can't forget Mootools" responses that end up falling short of what the OP is typically looking for.
Let's break out of the mold and make this thread different. Each response should contain a comprehensive summary of the poster's experiences with their favorite library. Try to include things like:
That should be a good list to work from, but is by no means complete. As the thread gets bigger, I'm certain we'll end up with a huge compendium of solid, real-world experiences for just about all of the libraries out there!
I'll post the first response to demonstrate what I mean. Hopefully this can become a good resource for people new to the world of javascript libraries and possibly point them in the right direction in making a choice.
I'm currently using Prototype for my project(s).
Before getting into the "why I chose prototype" section, let me provide a little bit of background for the project I'm working on.
My employer currently utilizes a CMS that they inherited from the late 90's. The system, although antiquated, does the job for which it was intended and has been doing so for awhile. "If it ain't broke, don't fix it", right? As the needs of our business has changed over time, so has the needs of the CMS. For many years, the Web 1.0 methods have worked fine:
Recently, however, the change requests from our business partners have become more and more complicated. Web 1.0 model wasn't going to work. We had to build several "Rich Interfaces" to enable some of the more complicated business requirements.
For example, the business needed a means to create ad-hoc surveys - with the ability to search for and reuse questions/answers from other surveys, the ability to copy questions/answers and edit them as 'new', and create new questions/answers on the fly. A Web 1.0 application to locate, assign, and save these surveys would have been too bulky and required way too many clicks to get around.
There were additional requirements such as the ability to create/read/update/delete various tree structures (and nest them) for navigation of certain learning materials.
Based on these requirements, we were faced with a couple of choices:
As most IT folks know, rolling your own is time consuming. In addition, the accounting folks NEVER want to pay for all that development time. Option 2 was our choice, so we did some research. There are many many other libraries out there that we looked at, but only a few were given a more thorough review (listed here in alphabetical order):
I'm not going to express in any great detail how each library "stacked up", but here's a very short list:
While the eye-candy was important, we really needed some heavy-hitting on the client-side to process a lot of data. For example. One feature in our survey tool was the ability to create/edit questions. We created a question 'class' and bound it to certain icons' click events:
var Question = Class.create();
Question.prototype = {
initialize:function(id,params) {
//some initialization stuff
Event.observe($('q_icon' + id),'click', this.clickFunction.bindAsEventListener(this));
},
clickFunction:function() {
//do stuff to this object's params
}
};
When a question was created, we did something like this:
var something = new Question(numericId,{
"txt":"What is your quest?",
"answers":[
"We seek the holy grail",
"To find a shrubbery",
"I want to be in grave danger",
"To discover huge tracts of land"
]
});
Anytime the 'edit' icon was clicked, for example, the closure to the question object would allow us to directly edit that object's parameters without having to search for it in the DOM or elsewhere in some 'master' object.
While prototype's Ajax.Request object isn't any more grand than the others, we do enjoy the Ruby-esque means to loop through the returned JSON from searches:
returnedArray.each(function(result) {
//do stuff to display results and build objects
});
Beyond the client-side processing of objects, we don't need any animation, so a simple $('elementName').hide() or .show() is sufficient.
For implementation, our first hurdle was the download. Prototype is pretty big. After we minified it and enabled gzip on the server, it was reduced to around 30KB; much more palatable and kept the bosses happy (we pay for bandwidth)
The second hurdle was the learning curve. Many developers would consider JavaScript to be a toy language meant for rollovers and alert boxes.
I think the biggest benefit to using prototype is now our code has some commonality. Everyone on our team knows how to use .each, $(), and just about every other method/extension that prototype provides. The common code base makes it a lot easier to read each others' code (especially if someone is on vacation) and there's no bickering over which library is better. While it's great that jQuery would do better for feature A and YUI has a better widget for feature B and mootools has a cool accordion; it's far less hassle when everything is based on a single library.
If you're trying to decide on a library, I recommend prototype for the following cases:
I've purposefully avoided bringing in Scriptaculous to this discussion because we've considered it more of a 'fringe benefit' to Prototype rather than an integral part of our needs.
There you have it - my reasons for (currently) using prototype.
It's called jQuery UI:. It's more than just graphical extensions, it's a library of widgets that allow you to rapidly build rich internet apps.
Hi there,
I am a huge fan of jQuery and Dojo. I am working a lot with Dojo right now.
One issue I have with prototype is that it rewrites some of the global namespace - such as array. When you use prototype you get their arry - not a plain old javascript array - and you have no choice.
One thing I like about Dojo and jQuery is that they respect the global namespace - for when you just want JavaScript, but both offer powerful features. As I'm working with Dojo's object oriented architecture to create some fairly robust apps - I am liking it more and more.
The coolest thing is Extjs.. i know it's a resource killer but they have there something amazing
The X Library.
I didn't consider any other libraries. X is my own library so I'm more comfortable with it than with someone else's. That's not to say that I don't make use of other people's open-source code - I do when the need arises. And of course, I do study the source code of other libraries .
Recently I developed a fully Ajax enabled "Dashboard" type application (think "google analytics") for my employer, and X has served me extremely well in this project. I didn't have any real problems in using X to do this but it did reveal some areas where X could be improved.
If you are looking for syntactic sugar or lots of UI objects or OOP support - then X is not for you. X is a straight-forward, function library. It is very small, extremely cross-browser, and robust (I've been developing it since 1999). The "core" DHTML functions provide a great foundation upon which to build your own objects. You don't have to include the entire library into your project - I provide a utility that searches your project files and creates a custom X library file containing only the functions used in your project.
BTW... if you are the copy-n-paste type, then X is definitely not for you
I absolutely love YUI, with all of the extensive documentation, and proper implementation of design patterns, and emphasis on OO and event driven approach to JavaScript. To me, YUI is a whole JavaScript resource and coding philosophy.
Now if you just want a really great collection of scripts that require less engineering prowess ... I'd go with JQuery, hands down. Different tools for different teams.
To me, YUI is for a serious engineering team and pairs great with a Java/MVC backend. JQuery will be a lot more reasonable to PHP and probably a lot of .Net developers as well, who are more scripters/coders than engineers per se.
I would generally avoid Dojo or Prototype, or Rico.
Best Library Ever.
A good overview of available JS libraries: JSDB.io | http://community.sitepoint.com/t/javascript-library-summary/3477 | CC-MAIN-2015-11 | refinedweb | 1,472 | 62.17 |
Poorly documented code department
I find it amazing sometimes how hard it is to figure out how to code something so seemingly simple. I am working with my developer to create a new setup wizard for the ASP.NET Quickstart samples that will automatically download, install, and configure SQL Server Express. The recommended way to check for SQL Express is to query WMI to find out if it is installed and running, etc.
Well it turns out that writing .NET code to interact with WMI was not as easy as I expected. I found the System.Management namespace documentation and sample code to be pretty poor and I had to email someone on the WMI team to figure out how to make it work for me.
The biggest problem that I found is that the SDK documentation does not provide any simple examples of how to query for a WMI object that exists outside of the default namespace, /root/cimv2. Since I’m looking for SQL Server Express I need to look for the \root\Microsoft\SQL Server\ComputerManagement\.
Here is the easy way to do.
ManagementObject SQLObj1 = new ManagementObject(
"\\root\\Microsoft\\SQLServer\\ComputerManagement",
"SInstance.InstanceName='SQLEXPRESS'",
null);
Console.WriteLine("'SInstance.Flags > {0}", SQLObj1["NumberOfFlags"]);
The first parameter to the ManagementObject constructor, ManagementObject (String, String, ObjectGetOptions) is the WMI namespace that I am looking for.
The second parameter is the used to find a particular class object in the namespace I specified.
Okay so it took me some time to get the first part working. I could do that without the help of the WMI team, but it wasn’t as straight forward as it should have been. I’ll file a bug and get a new snippet.
Now for the fun stuff:
What I really wanted to get was the SQL Express SqlService object from the \root\Microsoft\SQLServer\ComputerManagement namespace. When I look at that the SqlService class in CimStudio I find that it has two properties that define the primary key. That means I can’t use the same query as above. I had to email the WMI team to find out that in order to define a path to a multikey property with the .NET WMI provider you need to separate the key properties with a comma. So to get what I want I had to do write the following code.
ManagementObject SQLObj2 = new ManagementObject(
"\\root\\Microsoft\\SQLServer\\ComputerManagement",
"SqlService.ServiceName='MSSQL$SQLEXPRESS',SQLServiceType=1",
null);
Console.WriteLine("'SqlService.State > {0}", SQLObj2["State"]);
I’m going to try to get the docs updates to contain some details and code samples on this scenario incase anyone else can’t figure this out. In the mean time, this blog entry here to help out anyone else that is running into the same issue.
Now it’s time to do some more coding. I need to figure out how to use System.Management to get a list of the SqlService class objects so that I can sort through them and find the one that I am interested in. I hope that is easier to figure out. | http://blogs.msdn.com/b/jbower/archive/2004/08/03/207380.aspx | CC-MAIN-2015-32 | refinedweb | 517 | 64.71 |
Mennonite Church USA Archives. Modified by Opensource.com. CC BY-SA 4.0.
But a pet peeve of mine is copying and pasting. If you’re moving data from its source to a standardized template, you shouldn’t be copying and pasting either. It’s error-prone, and honestly, it’s not a good use of your time.
So for any piece of information I send out regularly which follows a common pattern, I tend to find some way to automate at least a chunk of it. Maybe that involves creating a few formulas in a spreadsheet, a quick shell script, or some other solution to autofill a template with information pulled from an outside source.
But lately, I’ve been exploring Python templating to do much of the work of creating reports and graphs from other datasets.
Python templating engines are hugely powerful. My use case of simplifying report creation only scratches the surface of what they can be put to work for. Many developers are making use of these tools to build full-fledged web applications and content management systems. But you don’t have to have a grand vision of a complicated web app to make use of Python templating tools.
Why templating?
Each templating tool is a little different, and you should read the documentation to understand the exact usage. But let’s create a hypothetical example. Let’s say I’d like to create a short page listing all of the Python topics I've written about recently. Something like this:
Simple enough to maintain when it’s just these three items. But what happens when I want to add a fourth, or fifth, or sixty-seventh? Rather than hand-coding this page, could I generate it from a CSV or other data file containing a list of all of my pages? Could I easily create duplicates of this for every topic I've written on? Could I programmatically change the text or title or heading on each one of those pages? That's where a templating engine can come into play.
There are many different options to choose from, and today I'll share with you three, in no particular order: Mako, Jinja2, and Genshi.
Mako
Mako is a Python templating tool released under the MIT license that is designed for fast performance (not unlike Jinja2). Mako has been used by Reddit to power their web pages, as well as being the default templating language for web frameworks like Pyramid and Pylons. It's also fairly simple and straightforward to use; you can design templates with just a couple of lines of code. Supporting both Python 2.x and 3.x, it's a powerful and feature-rich tool with good documentation, which I consider a must. Features include filters, inheritance, callable blocks, and a built-in caching system, which could be import for large or complex web projects.
Jinja2
Jinja2 is another speedy and full-featured option, available for both Python 2.x and 3.x under a BSD license. Jinja2 has a lot of overlap from a feature perspective with Mako, so for a newcomer, your choice between the two may come down to which formatting style you prefer. Jinja2 also compiles your templates to bytecode, and has features like HTML escaping, sandboxing, template inheritance, and the ability to sandbox portions of templates. Its users include Mozilla, SourceForge, NPR, Instagram, and others, and also features strong documentation. Unlike Mako, which uses Python inline for logic inside your templates, Jinja2 uses its own syntax.
Genshi
Genshi is the third option I'll mention. It's really an XML tool which has a strong templating component, so if the data you are working with is already in XML format, or you need to work with formatting beyond a web page, Genshi might be a good solution for you. HTML is basically a type of XML (well, not precisely, but that's beyond the scope of this article and a bit pedantic), so formatting them is quite similar. Since a lot of the data I work with commonly is in one flavor of XML or another, I appreciated working with a tool I could use for multiple things.
The release version currently only supports Python 2.x, although Python 3 support exists in trunk, I would caution you that it does not appear to be receiving active development. Genshi is made available under a BSD license.
Example
So in our hypothetical example above, rather than update the HTML file every time I write about a new topic, I can update it programmatically. I can create a template, which might look like this:
And then I can iterate across each topic with my templating library, in this case, Mako, like this:
from mako.template import Template
mytemplate = Template(filename='template.txt')
print(mytemplate.render(topics=("Python GUIs","Python IDEs","Python web scrapers")))
Of course, in a real-world usage, rather than listing the contents manually in a variable, I would likely pull them from an outside data source, like a database or an API.
These are not the only Python templating engines out there. If you’re starting down the path of creating a new project which will make heavy use of templates, you’ll want to consider more than just these three. Check out this much more comprehensive list on the Python wiki for more projects that are worth considering.
6 Comments | https://opensource.com/resources/python/template-libraries | CC-MAIN-2022-40 | refinedweb | 907 | 62.78 |
In article <CnE9H5.DnH@spk.hp.com>, Bill Baker <baker@spk.hp.com> wrote:
>
> Question: How does one single-step a python program (note: this is
> not how do you debug a python statement or group of
> statements but how is an entire program single-stepped)
>
>From pdb.doc:
| s(tep)
| Execute the current line, stop at the first possible occasion
| (either in a function that is called or in the current function).
|
| Continue execution until the next line in the current function
| is reached or it returns.
| (!))
Thus you can:
$ python
Python 1.0.1 (Mar 15 1994)
>>> import pdb
>>> pdb.run( 'import fin' )
> <string>(0)
(Pdb) s
> <string>(1)
(Pdb) s
> ./fin.py(0)
(Pdb) s
> ./fin.py(1): import sys
(Pdb) n
> ./fin.py(2): import rand
(Pdb) n
> ./fin.py(4): def func():
[ lines deleted ... Note the 2 occurances of 'def main' - one
is the function being defined, the other is displayed when
main() is actually executed. This is because the debugger gets
the source line from lineno in the source file. The one problem
with pdb is that if you define a function interactively, you
don't get the source line display - you just get "<stdin>" . ]
> ./fin.py(40): def main():
(Pdb) s
> ./fin.py(48): main()
(Pdb) s
> ./fin.py(40)main(): def main():
(Pdb) s
> ./fin.py(41)main(): for i in range(20):
(Pdb) s
> ./fin.py(41)main(): for i in range(20):
(Pdb) s
> ./fin.py(42)main(): try:
(Pdb) s
> ./fin.py(43)main(): test()
(Pdb) s
> ./fin.py(14)test(): def test():
(Pdb) s
> ./fin.py(15)test(): try:
(Pdb) s
> ./fin.py(16)test(): catch_type = "" # assume we catch nothing
(Pdb) !print catch_type # haven't stepped thru that line, so not yet defined
*** NameError: catch_type
(Pdb) s
> ./fin.py(17)test(): problem = 1 # presume an exception will take place
(Pdb) !print catch_type # now it's defined to be the null-string
(Pdb)
>I read the pdb.doc file and have tried several things but there doesn't seem
>to be as easy a method as perl's '-d' comand-line parameter to enter
>debugging mode. The only way I have found is to comment-out mainline code
>and:
>> python
>Python 1.0.1 (26 January 1994)
>>>> import pdb
>>>> pdb.run('import myprogram')
>> <string>(0)
>(Pdb)
>.
>.
>.
>
>This lets me re-enter the mainline through the keyboard but I _do_ miss
>being able to emulate cdb inside of a running perl program through '-d'.
>I _must_ be missing something!
>
But I'm not sure if you mean something else there. ( I'm not much of a
Perl hacker, and I've only used debug mode to force Perl to be
interactive, which is already the default for Python. )
If you just mean being able to do it from the command line, you can:
$ python -c 'import pdb; pdb.run( "import myprogram" )
I don't understand what you need to comment out - unless you are
referring to a difference in scope between
$ ./myprogram.py
where myprogram is executing within __main__ 's scope, and the previous
case, where myprogram has it's own scope.
[ If this is a problem, you can use a technique like I used in
"ImportModule" to coerce the default namespace. That function
was posted to the python-list mailing list - I'll probably
repost a newer version here when I get the chance. ]
Note: Python has a '-d' switch, but that is debugging for the
Python interpreter's parser. 'pdb', and some of the other debugging
modules are just normal user written modules. It might be a nice
idea to add another command line option to automatically put you into
the debugger, but we would need to add an environment variable option,
PYTHONDEBUGMODULE or PYTHONDEBUGGER, to indicate *which* debugger to
load. I think it's a nice feature to have a user extesible Python
debugger written IN Python.
- Steve Majewski (804-982-0831) <sdm7g@Virginia.EDU>
- UVA Department of Molecular Physiology and Biological Physics | http://www.python.org/search/hypermail/python-1994q1/0535.html | CC-MAIN-2013-48 | refinedweb | 666 | 75.91 |
Nicer Ansible output for Puppet tasks
04/16/15
In a previous post, I wrote about executing Puppet from within an Ansible playbook. But the output did not look very nice. In this post I take a closer look at how to change that.
Just as a reminder, the output of Puppet looks like this, when called from inside Ansible:
Ansible offers callback plugins. And according to this gist you can use them to change Ansible’s output. So, does this also work for the Puppet output?
As stated in the docs of Ansible, the parameter callback_plugins in
ansible.cfg tells Ansible where to find the plugins. On my system it is
/usr/share/ansible_plugins/callback_plugins. So I create
human_log.py in this directory. Calling Ansible, shows it does not work completely. It is not working for the debug task:
But do we really need the debug task? It is just a workaround to get the Puppet output when something changed or failed. With the new Ansible plugin it seems possible to realize this without the debug tasks.
Currently the plugin changes the output only for
runner_on_ok and
runner_on_failed. But we need it to only log for
runner_on_changed. I could not find a reference Ansible implements this inside callbacks, instead Ansible hides it inside the
res object. As shown in this gist, the status in
runner_on_ok can be ok or changed.
Let us change the human_log.py to just print the output when something changed:
def runner_on_ok(self, host, res): if res.pop('changed', False): human_log(res) else: pass
This little change fixes the output and makes it even possible to remove the Ansible debug task. The output now looks like this when something changed:
As you can see, the plugin also removes the unicode signes, which makes it even more readable. And this is the output when everything passes:
This Ansible callback plugin is the solution to our logging problem. With this callback plugin, we can change the Puppet output and also shorten our playbook. When you got question about this topic, do not hesitate to contact me or leave a comment.
Comment | https://blog.codecentric.de/en/2015/04/nicer-ansible-output-for-puppet-tasks/ | CC-MAIN-2017-43 | refinedweb | 354 | 66.64 |
Introduction to Web API
In this article we are going to focus on what is ASP.NET Web API(Application Programming Interface) and why it is needed. The Prerequisites required to learn Web API. Tools to test a Web API service. WEB API is used to create HTTP services.
In this article we are going to focus on what is ASP.NET Web API and how to use it. The Prerequisites to learn Web API.
What is ASP.NET Web API
It is a framework for creating web API s on top of .NET Framework. It makes creating HTTP service simple and easy and supports wide range of devices.
Why Web APIs
1.Using Web API, We can not only expose data but also create our own services
2. We can use it for a wide range of clients may be a Browser application or a Mobile Device or any Desktop applications.
3. Makes sending/receiving data over HTTP to a wide range of devices very easy.
4. The client can be a service from other language like ruby or python any xaml application or a JS client.
5.Supports data formats such as JSON / XML and allows clients to provide the required response data format. Provision to provide our own data formatting using MediaTypeFormatters.
6.Simple and clean urls to understand such as :
7.Since it is based on http protocol it also supports caching.
8.Easy to consume from Javascript.
9.It can be hosted in IIS or any exe file or asp.net or unit test project.
10. It uses routing similar to ASP.NET MVC.
Basic components of Web API
1.Controller:
It is the heart of the Web API application.
It exposes the actions or the resources that can be consumed by the client.
2.Handlers:
IT allows us to keep track of the incoming request or the outgoing response
Facilitate Authentication.
3.Filters:
To provide additional functionality on top of the basic functionality.
Installation Instructions:
It is already included with ASP.NET MVC 4.
Visual Studio 2010
Download and install sp1 for Visual Studio 2010.
Download and install MVC 4 Project from Microsoft site here
Visual Studio 2012
Already Built into it.
Prerequisites
Good to have knowledge in MVC architecture but not mandatory.
Good to have knowledge in WCF data services but not mandatory.
C# knowledge is required.
Knowledge in JSON/XML.
How to test Web API services
Fiddler is a great tool to test Web API services. It also provides the facility to tweak the request headers including the content format we expect from service.
Web API in action
Now we will see how to create a simple Web API application using Visual Studio 2012.
Here we will create a Web API that returns a list of students.
Step1: Launch Visual Studio 2012 -> File -> New -> Project -> On the Left Side of open dialog box Select Installed ->Templates -> Visual C# -> Web -> Then select ASP.NET MVC4 Web Application. Name it as "MyFirstWebAPIApp".
Step2: In the New ASP.NET MVC 4 Project window select Empty as shown below and click on ok:
Step3: Right click Models Folder and Add new class "Student".
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
namespace MyFirstWebAPIApp.Models
{
public class Student
{
public Student(){}
public Student(int id,string name,DateTime joiningDate,string cls)
{
this.StudentId = id;
this.StudentName = name;
this.JoiningDate = joiningDate;
this.Class = cls;
}
public int StudentId { get; set; }
public string StudentName { get; set; }
public DateTime JoiningDate { get; set; }
public string Class { get; set; }
}
}
Step 4:Right click Controllers folder and add a new class "StudentController" as shown below. This controller handles HTTP requests from the client.
namespace MyFirstWebAPIApp.Controllers
{
public class StudentController : ApiController
{
public List
{
List
lst.Add(new Student(1, "john", new DateTime(2014, 1, 1), "B.Tech I year"));
lst.Add(new Student(1, "robert", new DateTime(2014, 2, 1), "B.Tech I year"));
lst.Add(new Student(1, "tina", new DateTime(2014, 1, 4), "B.Tech I year"));
return lst;
}
}
}
Please note that the controller class inherits from the ApiController class which defines the methods and properties for the web api controller.
The configuration settings for the Web API are stored in the GlobalConfiguration object which inturn contains the Httpconfiguration object.
In the App_Start folder there is a WebApiConfig class which is used for Web API configuration.
In the Global.asax file, In the Application_Start event,Register method of the WebApiConfig class is used to configure the Web API. It is used to add the default WebAPI route.
In the register method, by default it contains the code to route the requests to appropriate controller.
Step 5:Build the project and Press Ctrl +F5 to run the project.
Now the browser window opens. Copy the url.
Step 6:Launch the Fiddler tool. If Fiddler is not already installed. Download and install it from this url
In the Fiddler Web Debugger window, click on Composer and paste the url() as shown below. The port number may vary based on the availability of the port.
Step 7: Click on the execute tab. Once the request is executed and response is received. Double click on the left hand side window which says URL:/api/Student. This displays the result in JSON format as shown below:
Step 8:To view the output in xml format, We need to update the accept header saying we want the result in xml format by specifying:Accept: application/xml in the Request Header as shown below:
Now click on execute button again and see that the result is now displayed in xml format as shown below:
Get() lst = new List (); | http://www.dotnetspider.com/resources/45573-Introduction-to-Web-API.aspx | CC-MAIN-2017-13 | refinedweb | 941 | 68.77 |
I need some small help hopefully. I thought i could figure this out on my own but obviously since i am posting to this board for the first time, well you know.
I am trying to get this program to calculate change tendered by breaking it down by dollars, half-dollars, quarters, dimes, nickels, and pennies. Reliaze this is just the beginning of the class so not allowed to use loops, modulus, etc.. this is why i am stuck.
Code:#include <iostream>// cin, cout, <<, >> using namespace std; int main() { cout << "Enter the amount of purchase" <<"\n"; double purchaseAmt; cin >> purchaseAmt; cout << "Enter your payment amount given" <<"\n"; double paymentAmt; cin >> paymentAmt; double changeAmt = paymentAmt - purchaseAmt; cout << "\nYour change back is: " << changeAmt << "\n"; double halfDollar = changeAmt / .50; double quarters = changeAmt / .25; double dimes = changeAmt / .10; double nickels = changeAmt / .5; double pennies = changeAmt; cout << "\nhalfDollar back: " << halfDollar << "\n"; cout << "\nQuarters back: " << quarters << "\n"; cout << "\nDimes back: " << dimes << "\n"; cout << "\nNickels back: " << nickels << "\n"; return 0; } | http://cboard.cprogramming.com/cplusplus-programming/79250-calculating-change-basic-commands.html | CC-MAIN-2015-27 | refinedweb | 163 | 72.05 |
Introduction: Makey Makey Quiz Engine
For those of you who have not used a Makey Makey before, they are essentially PIC boards with some additional clever really sensitive electronics which can detect a short circuit, even when conducting through a person (or their typical example some fruit). They natively interface with the computer as a keyboard and mouse, so it is really easy to interface it with existing applications.
Knowing this, I thought I would write a custom Qt application as my Quiz interface, and use the Makey Makey to interact with each of my players. Essentially, when one of the players hits their button, it will bring up a message and lock out all other player from pressing their button. That way you will know who pressed their button first so you know who gets to answer the question first.
Step 1: Each Player
Each of the players needs 2 wires, one wire carrying the button that they are pressing and one with the ground (labelled EARTH on the Makey Makey board).
I found some two core wire, which I stripped back on both ends, then carefully using wire stripper also stripped the inner cores revealing the copper.
Step 2: Wiring to the Makey Makey
As all users need a button wire and a ground wire, I decided that blue would be my ground and twisted them all together. I then soldered and trimmed down all of the wires ready for putting onto the board. Fortunately the Makey Makey has nice big pads to solder to, so it was really easy to solder it all together. The blue when to the bottom of the board and all the red wires to the up, down, left & right button. I ran all the wires to the left of the board, so that they could be neatly taped together.
Step 3: Creating the Buttons
So that each user can press their buttons as hard as they like I decided to tape a few bits of copper tape down to the table. Now essentially each user can hit the table (ideally centrally over the tape) to activate themselves in the Quiz engine on the computer. Unlike conventional buttons (which I have used in the past for these sorts of thing) it does not matter how hard you hit the table, so long as you don't break the table or tug on the wires. This means when people get a bit too enthusiastic when they have the answer they are not going to break my buttons again.
I just used a bit of masking tape and a sticker over the soldered ends so that the wire does not put too much strain on the tape.
Step 4: Round Reset
To reset between rounds I inserted a conventional button to the space bar. Now you can either hit the space key on the computer, or you can toggle the switch on the Makey Makey to reset who the winner is.
Step 5: The Qt Quiz Software
I created the Quiz Engine with Qt Creator (community edition) which is a quick and easy way to create C++ GUI applications in Windows, but also works well on Mac and Linux.
The code essentially saves the string of the winner into a gameWinner QString (so everyone's name needs to be unique). As soon as that is set, no other user can overwrite that QString until the system is reset with the space key. I have attached a zip of all the source code, but just so you can glance through I have included the mainWindow header and C++ source files below.
The GUI is currently very basic, but I intend to eventually add the ability for player's names to be adjusted and also include the photo of the Winner of that round. Another improvement would also be to have a runner up show, in case the Winner answers the question incorrectly.mainwindow.h
#ifndef MAINWINDOW_H #define MAINWINDOW_H #include #include namespace Ui { class MainWindow; } class MainWindow : public QMainWindow { Q_OBJECT public: explicit MainWindow(QWidget *parent = 0); ~MainWindow(); protected: void keyPressEvent(QKeyEvent *event); private slots: void on_reset_clicked(); private: Ui::MainWindow *ui; QString gameWinner; }; #endif // MAINWINDOW_Hmainwindow.cpp
#include "mainwindow.h" #include "ui_mainwindow.h" #include #define PLAYER1 "Dan" #define PLAYER2 "Divya" #define PLAYER3 "Diana" #define PLAYER4 "Jack" MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow) { ui->setupUi(this); this->setFocusPolicy(Qt::StrongFocus); qDebug() << "Launching SpyClub Quiz Engine"; gameWinner = ""; } MainWindow::~MainWindow() { delete ui; } void MainWindow::keyPressEvent(QKeyEvent *event) { if(((event->key() == Qt::Key_Up) || (event->key() == Qt::Key_Right) || (event->key() == Qt::Key_Down) || (event->key() == Qt::Key_Left)) && (gameWinner == "")) gameWinner = "TBC"; switch(event->key()) { case Qt::Key_Up: qDebug() << PLAYER1; if(gameWinner == "TBC") gameWinner = PLAYER1; break; case Qt::Key_Right: qDebug() << PLAYER2; if(gameWinner == "TBC") gameWinner = PLAYER2; break; case Qt::Key_Down: qDebug() << PLAYER3; if(gameWinner == "TBC") gameWinner = PLAYER3; break; case Qt::Key_Left: qDebug() << PLAYER4; if(gameWinner == "TBC") gameWinner = PLAYER4; break; case Qt::Key_Space: qDebug() << "Game Reset!"; gameWinner = ""; break; } if(gameWinner != "") ui->status->setText(gameWinner); else ui->status->setText("No Winner Yet..."); } void MainWindow::on_reset_clicked() { qDebug() << "Game Reset!"; gameWinner = ""; ui->status->setText("No Winner Yet..."); }
Step 6: Finished System
So here it is, everyone sits at one end of the table with the Quiz master on the other with the laptop. The Makey Makey is intentionally left visible, so that when people press their button an LED light's up to show that their button press has been acknowledged. Hope you enjoyed version 0.1 of my quiz system, I am sure it will be improved upon but I'm off to go have a quiz night :D
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4 years ago on Introduction
Thank you very much for posting this. I'm making somethinig very similar and needed the runner up. I've forked your code at added the needed bits for "runner up". It's not pretty, but it works enough... | https://www.instructables.com/id/Makey-Makey-Quiz-Engine/ | CC-MAIN-2020-29 | refinedweb | 991 | 56.29 |
lyn: “convert” .elf object files to EA events
(If you don’t get it yet keep reading it gets interesting)
(Actually if you never got into asm you can stop now but otherwise bear with me)
Usage: lyn [-nolink/-linkabs/-linkall] [-longcalls] [-raw] [-printtemp] [-autohook] <elf...>
Note: this is still fairly WIP: not a lot of testing have been done, and it will get at least a few extra updates to include extra functionnalities (see end of post for planned features list).
This tool is fairly simple at first glance: it takes an elf file as argument, and outputs EA code to stdout. But there’s a few things it does that will (hopefully) really change the way we’d go about asm hacking with EA.
But first, let’s clarify a few things:
What’s an elf?
ELF (Executable and Linkable Format) files are what your assembler or compiler will spit out, and what linkers will take to form executables. It contains various useful information, such as of course the compiled asm, but also a bunch more such as symbols and relocations that are specifically useful for linking.
The “old” method of inserting asm into the ROM with EA was simply to extract from that elf the assembled binary part and
#incbining it. While this worked, it also invoked the need to write a bunch of other instructions around that to properly link the asm to the rest of the hack/game (labels, post-asm literals, etc), and also was somehow limited (only one routine per file, cannot use relative jumps between files (such as
bls), etc).
What
lyn tries to do is to bring the functionalities of a proper linker to EA. That is (for now): defining elf global symbols as labels, and “converting” relocations (for example, a BL to
SomeSymbol) to EA code (same example:
BL(SomeSymbol)).
Why “lyn”?
linker>link>lin>lyn? Since Lyn a FE character & EA is a FE hacking tool it felt somewhat fitting. I probably wanted to it to be a special snowflake and not to be named
elf2ea or something like every other tool ¯\_(ツ)_/¯
How2use???
On its own
You can in theory just drop your elf file onto the
lyn executable, but what that will do is just write the output to a console and immediately close said console. What you can do is write a bat file that will call
lyn for the argument file, and output the whole thing to another file (probably using redirections). Here’s an example windows batch file (assumes
lyn is in the same folder):
@echo off "%~dp0lyn" "%~1" > "%~n1.event" pause
Save that as a .bat file (again, in a folder with
lyn in it) and drop an elf onto it to generate a corresponding .event file.
Using EA inctext
Quick reminder: what
#inctext does is include the result of the invoked command as EA code (as opposed to
#incext that includes it as raw binary data).
First we want to have the
lyn executable in the
<Event Assembler>/Tools folder, alongside the other tools like Png2Dmp, ParseFile, PFinder, etc.
Then we can simply in any event code use the following code to include the EA-ified elf file:
#inctext lyn "relative/path/to/some/file.elf"
Example of small asm hack that uses lyn
Ok so here I will walk us through remaking my “LolStats” hack by using
lyn (“LolStats” was a quick experiment hack that changes the way stat increase/growth work)
First, here’s the asm code I used (it’s a straight replacement for the routine at 0x02B9A0, that I labelled “GetStatIncrease”)
ASM
.thumb .set NextRN_100, 0x08000C64 @ Arguments: r0 = Growth @ Returns: r0 = Stat Increase GetStatIncrease: push {r4-r5, lr} mov r4, r0 mov r5, #0 Continue: ldr r3, =NextRN_100 mov lr, r3 .short 0xF800 sub r4, r0 @ r4 = (r4 - RN100) blt End @ if (r4 < 0) goto End; add r5, #1 @ stat++ b Continue End: mov r0, r5 pop {r4-r5} pop {r1} bx r1
Contains some labels, standard push/pop, a blh to a vanilla routine, etc… Fairly standard. Next, here’s the event file I used up until now:
Events
#include "Extensions/Hack Installation.txt" { PUSH; ORG 0x2B9A0 replaceWithHack(GetStatIncrease) POP ALIGN 4 GetStatIncrease: #incbin "asm/GetStatIncrease.bin" }
The first thing we are going to do is replace the whole
Label: #incbin stuff by a
#inctext to lyn:
Events but now with lyn
#include "Extensions/Hack Installation.txt" { PUSH; ORG 0x2B9A0 replaceWithHack(GetStatIncrease) POP ALIGN 4 #inctext lyn "asm/GetStatIncrease.elf" }
Note: Hack Installation is required for lyn to work too! This may change in the future tho
BUT if you only do that, you’ll get an error from EA saying that GetStatIncrease isn’t in scope, which is normal, since we need to tell our assembler to “expose” the label. So back to our asm source, and add the following:
.global GetStatIncrease .type GetStatIncrease, %function
Whereever you put it, it doesn’t really matter. What it does is that is tells the symbol
GetStatIncrease is
global and is of type “
function”. This is required information for lyn (and any proper linker really) to know which symbol to expose (make as label) and in what way.
If you add that, assemble to elf, and assemble the events, and it should have worked! You could use the
GetStatIncrease label defined in the asm source from EA! Of course that’s not all lyn does, since it also applies relocations: that means is that if you used in another asm source included through lyn the operation
bl GetStatIncrease, it would have worked!
And… what if I told you that using lyn would also allow use to make use of elf files generated by something that’s not a straight assembler with way more ease… Anyway that’s probably a story for another time.
Here is the final & complete version of my “lyn-ified” LolStats hack.
See next post for follow-up guide stuff:
BONUS: How to get an elf?
Here's your usual Assemble ARM.bat
@echo off SET startDir=%~p0\devkitARM\bin\ @rem Assemble into an elf SET as="%startDir%arm-none-eabi-as" %as% -g -mcpu=arm7tdmi -mthumb-interwork %1 -o "%~n1.elf" @rem Extract raw assembly binary (text section) from elf SET objcopy="%startDir%arm-none-eabi-objcopy" %objcopy% -S "%~n1.elf" -O binary "%~n1.dmp" echo y | del "%~n1.elf" pause
You can see there’s a specific part that generates an elf. Isolate that and you’re good! See:
There
@echo off SET startDir=%~p0\devkitARM\bin\ @rem Assemble into an elf SET as="%startDir%arm-none-eabi-as" %as% -g -mcpu=arm7tdmi -mthumb-interwork %1 -o "%~n1.elf" pause
Known Limitations
Because of how EA handles pointers & offsets, I cannot make
lyn relocate to anything that isn’t in the ROM (I’m mainly thinking RAM data), this is a problem that would probably be less of one once I add the ability for “anticipated linking” between elfs (we’d then just need to add an elf that contains absolute symbols pointing to said RAM data).
Planned features
- Bugfixes
- Support more relocations (such as ARM ones)
- More if ideas or suggestions come (feel free to suggest!)
As always, if you have any question, bug report or anything to ask/tell me, feel free to do so in this thread or on the FEU Discord!
Thanks to @MisakaMikoto and his thread of notes on asm calls for helping me understand some things faster and give me an idea of how to implement some extra functionalities later.
Other references used in coding the thing:
Have a great day! - StanH_ | https://feuniverse.us/t/ea-asm-tool-lyn-elf2ea-if-you-will/2986 | CC-MAIN-2021-39 | refinedweb | 1,276 | 65.66 |
Test Run
Test Harness Design Patterns
James McCaffrey and James Newkirk
Code download available at:TestRun0508.exe(147 KB)
Contents
The Six Basic Lightweight Test Harness Patterns
Flat Test Case Data
Hierarchical Test Case Data
Relational Test Case Data
The TDD Approach with the NUnit Framework
Conclusion
The Microsoft® .NET Framework provides you with many ways to write software test automation. But in conversations with my colleagues I discovered that most engineers tend to use only one or two of the many fundamental test harness design patterns available to them. Most often this is true because many developers and testers simply aren't aware that there are more possibilities.
Furthermore I discovered that there is some confusion and debate about when to use a lightweight test harness and when to use a more sophisticated test framework like the popular NUnit. In this month's column James Newkirk, the original author of NUnit, joins me to explain and demonstrate how to use fundamental lightweight test harness patterns and also show you their relation to the more powerful NUnit test framework.
The best way to show you where the two of us are headed is with three screen shots. Suppose you are developing a .NET-based application for Windows®. The screen shot in Figure 1 shows the fairly simplistic but representative example of a poker game. The poker application references a PokerLib.dll library that has classes to create and manipulate various poker objects. In particular there is a Hand constructor that accepts a string argument like "Ah Kh Qh Jh Th" (ace of hearts through 10 of hearts) and a Hand.GetHandType method that returns an enumerated type with a string representation like RoyalFlush.
Figure 1** System Under Test **
Now suppose you want to test the underlying PokerLib.dll methods for functional correctness. Manually testing the library would be time-consuming, inefficient, error-prone, and tedious. You have two better testing strategies. A first alternative to manual testing is to write a lightweight test harness that reads test case input and expected values from external storage, calls methods in the library, and compares the actual result with the expected result. When using this approach, you can employ one of several basic design patterns. Figure 2 shows a screen shot of a test run that uses the simplest of the design patterns. Notice that there are five test cases included in this run; four cases passed and one failed. The second alternative to manual testing is to use a test framework. Figure 3 shows a screen shot of a test run which uses the NUnit framework.
Figure 2** Lightweight Test Harness Run **
In the sections that follow, we will explain fundamental lightweight test harness design patterns, show you a basic NUnit test framework approach, give you guidance on when each technique is most appropriate, and describe how you can adapt each technique to meet your own needs. You'll learn the pros and cons of multiple test design patterns, and this information will be a valuable addition to your developer, tester, and manager skill sets.
Figure 3** NUnit Test Framework Run **
The Six Basic Lightweight Test Harness Patterns
It is useful to classify lightweight data-driven test harness design patterns into six categories based on type of test case storage and test case processing model. There are three fundamental types of test case storage: flat file, hierarchical, and relational. Additionally, there are two fundamental processing models: streaming and buffered. This categorization leads to six test harness design patterns, the cross-product of the storage types with the processing models.
Of course you can think of many other possibilities, but these six categories give you a practical way to think about structuring your lightweight test harnesses. Notice that this assumes that the test case storage is external to the test harness code. In general, external test case storage is better than embedding test case data with the harness code because external storage can be edited and shared more easily than embedded data. However, as we'll explain later, the test-driven approach is primarily a developer activity and typically uses embedded test case data which does have certain advantages over external data. Separately, NUnit can be used with external test case storage and can support both streaming and buffered processing models.
Flat Test Case Data
The most rudimentary type of test case data is flat data. The data in Figure 4 is the test case file used to generate the test run shown in Figure 2. Compared with hierarchical data and relational data, flat data is most appropriate when you have simple test case input and expected values, you are not in an XML-dominated environment, and you do not have a large test management structure.
Figure 4** Flat Test Case Data **
At a minimum every test case has an ID, one or more inputs, and one or more expected results. There is nothing profound about how to store test case data. Examples of flat data are text files, Excel worksheets, and individual tables in a database. Examples of hierarchical data stores are XML files and some .ini files. SQL Server™ databases and Access databases are examples of relational data stores when multiple tables are used in conjunction through relationships. Here you can see we're using a simple text file with a test case ID field, a single input field, and a single expected result field—simple and effective. We will discuss the pros and cons of each of the three storage types later in this column.
This pseudocode shows the basic streaming processing model:
open test case data store loop read a test case parse id, input, expected send input to system under test if actual result == expected result write pass result to external results file else write fail result to external results file end if end loop
The code in Figure 5 shows the main loop. The algorithm is implemented in Visual Basic® .NET, but any .NET-targeted language could be used. The complete source code for all examples is available in the code download that accompanies this column.
Figure 5 Streaming Flat Data Design
while ((line = sr.ReadLine()) != null) // main loop { tokens = line.Split(':'); // parse input caseid = tokens[0]; cards = tokens[1].Split(' '); expected = tokens[2]; Hand h = new Hand(cards[0],cards[1],cards[2],cards[3],cards[4]); // test actual = h.GetHandType().ToString(); Console.Write(caseid + " "); sw.Write(caseid + " "); if (actual == expected) // determine result { string rv = string.Format(" Pass {0} = {1}", h.ToShortString(), actual); Console.WriteLine(rv); sw.WriteLine(rv); } else { string rv = string.Format(" *FAIL* actual = {0} expected = {1}", actual, expected); Console.WriteLine(rv); sw.WriteLine(rv); } } //main loop
Notice that we echo test results to the command shell with a Console.WriteLine statement and write test results to an external text file with a call to StreamWriter.WriteLine. In general, it makes sense to save test case results to the same type of storage as your test case data, but this is considered to be more a matter of consistency than a technical issue.
We call the algorithm a streaming model because it resembles the .NET input-output streaming model; there is a continuous stream of test case input and test results. Now let's look at the buffered model. The pseudocode in Figure 6 is what we'll call the buffered processing model.
Figure 6 Buffered Algorithm
open test case data store loop read a test case from external storage save test data to in-memory data store end loop loop read a test case parse test case id, input, expected send input to system under test if actual result == expected result write pass result to in-memory data store else write fail result to in-memory data store end if end loop loop read test result from in-memory store write test result to external storage end loop
With the buffered test harness model we read all test case data into memory before executing any test cases. All test results are saved to an in-memory data store and then emitted to external storage after all test cases have been executed. In other words, test case input and results are buffered through the test system rather than streamed through the system. The code snippet in Figure 7 shows you how we implemented the buffered model using the test case data file that is shown in Figure 4.
Figure 7 Flat Data Buffered Design
// 1. read test case data into memory ArrayList cases = new ArrayList(); string line; while ((line = sr.ReadLine()) != null) cases.Add(line); // 2. main test processing loop ArrayList results = new ArrayList(); string caseid, expected, actual, result; string[] tokens, cards; for (int i = 0; i < cases.Count; ++i) { tokens = cases[i].ToString().Split(':'); // parse input caseid = tokens[0]; cards = tokens[1].Split(' '); expected = tokens[2]; Hand h = new Hand(cards[0],cards[1],cards[2],cards[3],cards[4]); actual = h.GetHandType().ToString(); result = caseid + " " + (actual == expected ? " Pass " + h.ToShortString() + " = " + actual : " *FAIL* actual = " + actual + " expected = " + expected); results.Add(result); // store result into memory } // 3. emit results to external storage for (int i = 0; i < results.Count; ++i) { Console.WriteLine(results[i].ToString()); sw.WriteLine(results[i]); }
If you compare the streaming processing model with the buffered model, it's pretty clear that the streaming model is both simpler and shorter. So why would you ever want to use the buffered model? There are two common testing scenarios where you should consider using the buffered processing model instead of the streaming model. First, if the aspect in the system under test involves file input/output, you often want to minimize the test harness file operations. This is especially true if you are monitoring performance. Second, if you need to perform some pre-processing of your test case input or post-processing of your test case results (for example aggregating various test case category results), it's almost always more convenient to have all results in memory where you can process them. The NUnit test framework is very flexible and can use external test case storage primarily with the buffered processing models. However, a complete discussion of how to use NUnit in these ways would require an entire article by itself and is outside the scope of this column.
Hierarchical Test Case Data
Hierarchical test case data, especially XML, has become very common. In this section we will show you the streaming and buffered lightweight test harness processing models when used in conjunction with XML test case data. Compared with flat test case data and relational data, hierarchical XML-based test case data is most appropriate when you have relatively complex test case input or expected results, or you are in an XML-based environment (your development and test effort infrastructure relies heavily on XML technologies). Here is a sample of XML-based test case data that corresponds to the flat file test case data in Figure 4:
<?xml version="1.0" ?> <TestCases> <case caseid="0001"> <input>Ah Kh Qh Jh Th</input> <expected>RoyalFlush</expected> </case> <case caseid="0002"> <input>Qh Qs 5h 5c 5d</input> <expected>FullHouseFivesOverQueens</expected> </case> ... </TestCases>
Because XML is so flexible there are many hierarchical structures we could have chosen. For example, the same test cases could have been stored as follows:
<?xml version="1.0" ?> <TestCases> <case caseid="0001" input="Ah Kh Qh Jh Th" expected="RoyalFlush" /> <case caseid="0002" input="Qh Qs 5h 5c 5d" expected=" FullHouseFivesOverQueens" /> ... </TestCases>
Just as with flat test case data, you can use a streaming processing model or a buffered model. In each case the algorithm is the same as shown in the basic streaming processing model algorithm and in the buffered algorithm that was shown in Figure 6. Interestingly though, the XML test case data model implementations are quite different from their flat data counterparts. Figure 8 shows key code from a C#-based streaming model implementation.
Figure 8 XML Data Streaming Design
xtw.WriteStartDocument(); xtw.WriteStartElement("TestResults"); while (!xtr.EOF) // main loop { if (xtr.Name == "TestCases" && !xtr.IsStartElement()) break; while (xtr.Name != "case" || !xtr.IsStartElement()) xtr.Read(); // advance to a <case> element if not there yet caseid = xtr.GetAttribute("caseid"); xtr.Read(); // advance to <input> input = xtr.ReadElementString("input"); // advance to <expected> expected = xtr.ReadElementString("expected"); // advance to </case> xtr.Read(); // advance to next <case> or </TestCases> cards = input.Split(' '); Hand h = new Hand(cards[0],cards[1],cards[2],cards[3],cards[4]); actual = h.GetHandType().ToString(); xtw.WriteStartElement("result"); xtw.WriteStartAttribute("caseid", null); xtw.WriteString(caseid); xtw.WriteEndAttribute(); xtw.WriteString(actual == expected ? " Pass " + h.ToShortString() + " = " + actual : " *FAIL* actual = " + actual + " expected = " + expected); xtw.WriteEndElement(); // </result> } // main loop
With a streaming model, we use an XmlTextReader object to read one XML node at a time. But because XML is hierarchical it is a bit tricky to keep track of exactly where we are within the file, especially when the nested becomes more extreme (in this particular example, the data is little more than a flat file, but it could be significantly more complex). We use an XmlTextWriter object to save test results in XML form. Now we'll show you a buffered approach for XML test case data. Figure 9 shows key code from a buffered processing model implementation.
Figure 9 XML Data Buffered Design
// 1. read test case data into memory XmlSerializer xds = new XmlSerializer(typeof(TestCases)); TestCases tc = (TestCases)xds.Deserialize(sr); // 2. processing loop string expected, actual; string[] cards; TestResults tr = new TestResults(tc.Items.Length); for (int i = 0; i < tc.Items.Length; ++i) // test loop { SingleResult res = new SingleResult(); res.caseid = tc.Items[i].caseid; cards = tc.Items[i].input.Split(' '); expected = tc.Items[i].expected; Hand h = new Hand(cards[0],cards[1],cards[2],cards[3],cards[4]); actual = h.GetHandType().ToString(); res.result = (actual == expected) ? // store results into memory "Pass " + h.ToShortString() + " = " + actual : "*FAIL* " + "actual = " + actual + " expected = " + expected; tr.Items[i] = res; } // 3. emit results to external storage XmlTextWriter xtw = new XmlTextWriter("..\\..\\TestResults.xml",System.Text.Encoding.UTF8); XmlSerializer xs = new XmlSerializer(typeof(TestResults)); xs.Serialize(xtw,tr);
We use an XmlSerializer object from the System.Xml.Serialization namespace to read the entire XML test case file into memory with a single line of code and also to write the entire XML result file with a single line of code. Of course, this requires us to prepare appropriate collection classes (TestCases and TestResults in the code) to hold the data.
Unlike flat test case data, with XML data the buffered model test harness code tends to be shorter and simpler. So when might you consider using a streaming model in conjunction with XML test case data? Most often you will want to use a streaming model when you have a lot of test cases to deal with. Reading a huge amount of test case data into memory all at once may not always be possible, especially if you are running stress tests under conditions of reduced internal memory.
Relational Test Case Data
In this section we'll describe the streaming and buffered lightweight test harness processing models when used in conjunction with SQL test case data. Compared with flat data and hierarchical data, relational SQL-based test case data is most appropriate when you have a very large number of test cases, or you are in a relatively long product cycle (because you will end up having to store lots of test results), or you are working in a relatively sophisticated development and test infrastructure (because you will have lots of test management tools). Figure 10 shows test case data thas has been stored in a SQL database.
Figure 10** SQL-based Test Case Data **
Just as with flat test case data and hierarchical data, you can use a streaming processing model or a buffered model. The basic streaming and buffered models described earlier will be the same.
The streaming model implementation is included in this column's download. If you examine the code you'll see that for a streaming model we like to use a SqlDataReader object and its Read method. For consistency we insert test results into a SQL table rather than save to a text file or XML file. We prefer to use two SQL connections—one to read test case data and one to insert test results. As with all the techniques in this column, there are many alternatives available to you.
The code for the buffered processing model can be downloaded from the MSDN Magazine Web site. Briefly, we connect to the test case database, fill a DataSet with all the test case data, iterate through each case, test, store all results into a second DataSet, and finally emit all results to a SQL table.
Using relational test case data in conjunction with ADO.NET provides you with many options. Assuming memory limits allow, we typically prefer to read all test case data into a DataSet object. Because all the test case data is in a single table, we could also have avoided the relatively expensive overhead of a DataSet by just using a DataTable object. However in situations where your test case data is contained in multiple tables, reading into a DataSet gives you an easy way to manipulate test case data using a DataRelation object. Similarly, to hold test case results we create a second DataSet object and a DataTable object. After running all the test cases we open a connection to the database that holds the results table (in this example it's the same database that holds the test case data) and write results using the SqlDataAdapter.Update method.
Recall that when using flat test case data, a streaming processing model tends to be simpler than a buffered model, but that when using hierarchical XML data, the opposite is usually true. When using test case data stored in a single table in SQL Server, a streaming processing model tends to be simpler than a buffered model and the technique of choice. When test case data spans multiple tables, you'll likely want to use a buffered processing model.
The TDD Approach with the NUnit Framework
In the previous sections you've seen six closely related lightweight test harness design patterns. A significantly different but complementary approach is to use an existing test framework. The best known framework for use in a .NET environment is the elegant NUnit framework as shown in Figure 3. See the MSDN®Magazine article by James Newkirk and Will Stott at Test-Driven C#: Improve the Design and Flexibility of Your Project with Extreme Programming Techniques for details. The code snippet in Figure 11 shows how you can use NUnit to create a DLL that can be used by NUnit's GUI interface. And the code snippet in Figure 12 shows how you can use NUnit with external XML test case data to create a DLL that can be used by NUnit's command-line interface.
Figure 12 NUnit Approach with External XML Test Cases
[Suite] public static TestSuite Suite { get { TestSuite testSuite = new TestSuite("XML Buffered Example"); using(StreamReader reader = new StreamReader("TestCases.xml")) { XmlSerializer xds = new XmlSerializer(typeof(TestCases)); TestCases testCases = (TestCases)xds.Deserialize(reader); foreach(Case testCase in testCases.cases) { string[] cards = testCase.input.Split(' '); HandType expectedHandType = (HandType)Enum.Parse( typeof(HandType), testCase.expected); Hand hand = new Hand(cards[0], cards[1], cards[2], cards[3], cards[4]); testSuite.Add(new HandTypeFixture( testCase.id, expectedHandType, hand.GetHandType())); } } return testSuite; } }
Figure 11 NUnit Approach with Embedded Test Cases
using NUnit.Framework; using PokerLib; [TestFixture] public class HandFixture { [Test] public void RoyalFlush() { Hand hand = new Hand("Ah", "Kh", "Qh", "Jh", "Th"); Assert.AreEqual(HandType.RoyalFlush, hand.GetHandType()); } ... // other tests here }
You may be wondering whether it's better to use NUnit or to write a custom test harness. The best answer is that it really depends on your scenarios and environment, but using both test techniques together ensures a thorough test effort. The NUnit framework and lightweight test harnesses are designed for different testing situations. NUnit was specifically designed to perform unit testing in a test-driven development (TDD) environment, and it is a very powerful tool. A lightweight test harness is useful in a wide range of situations, such as when integrated into the build process, and is more traditional than the NUnit framework in the sense that a custom harness assumes a conventional spiral-type software development process (code, test, fix).
A consequence of NUnit's TDD philosophy is that test case data is typically embedded with the code under test. Although embedded test case data cannot easily be shared (for example when you want to test across different system configurations), embedded data has the advantage of being tightly coupled with the code it's designed to test, which makes your test management process easier. Test-driven development with NUnit helps you write code and test it. This is why embedded tests with NUnit are acceptable—you change your tests as you change your code. Now this is not to say that the two test approaches are mutually exclusive; in particular NUnit works nicely in a code-first, test-later environment, and can utilize an external test case data source. And a lightweight test harness can be used in conjunction with a TDD philosophy.
The NUnit framework and custom lightweight test harnesses have different strengths and weaknesses. Some of NUnit's strengths are that it is a solid, stable tool, it is a nearly a de-facto standard because of widespread use, and it has lots of features. The strengths of custom test harnesses are that they are very flexible, allowing you to use internal or external storage in a variety of environments, test for functionality as well as performance, stress, security and other types of testing, and execute sets of individual test cases or multiple state change test scenarios.
Conclusion
Let's briefly summarize. When writing a data-driven lightweight test harness in a .NET environment you can choose one of three types of external test case data storage: flat data (typically a text file), hierarchical data (typically an XML file), or relational data (typically a SQL Server database). Often you will have no choice about the type of data store to use because you will be working in an already existing development environment. Flat data is good for simple test case scenarios, hierarchical data works very well for technically complex test case scenarios, and relational data is best for large test efforts.
When writing a lightweight test harness you can employ either a streaming processing model or you can choose a buffered processing model. A streaming processing model is usually simpler except when used with truly hierarchical or relational data, in which case the opposite is true. A streaming model is useful when you have a very large number of test cases, and a buffered model is most appropriate when you are testing for performance or when you need to process test cases and results. Using a test framework like NUnit is particularly powerful for unit testing when you are employing a TDD philosophy.
With the .NET environment and powerful .NET-based tools like NUnit, it's possible to write great test automation quickly and efficiently. The release of Visual Studio® 2005 will only enhance your ability to write test automation and the Team System version in Visual Studio 2005 will have many NUnit-like features. With software systems increasing in complexity, testing is more important than ever. Knowledge of these test harness patterns as well as of frameworks like NUnit will help you test better and produce better software systems..
James Newkirk is the development lead for the Microsoft Platform Architecture Guidance team, building guidance and reusable assets for enterprise customers through the patterns & practices series. He is the coauthor of Test Driven Development in Microsoft .NET (Microsoft Press, March 2004). | https://docs.microsoft.com/en-us/archive/msdn-magazine/2005/august/test-run-test-harness-design-patterns | CC-MAIN-2019-51 | refinedweb | 3,980 | 53.61 |
Code splitting. Code splitting is everywhere. However, why? Just because there is too much of javascript nowadays, and not all are in use at the same point in time.
JS is a very heavy thing. Not for your iPhone Xs or brand new i9 laptop, but for millions(probably billions) of slower devices owners. Or, at least, for your watches.
So - JS is bad, but what would happen if we just disable it - the problem would be gone... for some sites, and be gone "with sites" for the React-based ones. But anyway - there are sites, which could work without JS... and there is something we should learn from them...
Code splitting
Today we have two ways to go, two ways to make it better, or to not make it worse:
1. Write less code
That's the best thing you can do. While
React Hooks are letting you ship a bit less code, and solutions like
Svelte let you generate just less code than usual, that's not so easy to do.
It's not only about the code, but also about functionality - to keep code "compact" you have to keep it "compact". There is no way to keep application bundle small if it's doing so many things (and got shipped in 20 languages).
There are ways to write short and sound code, and there are ways to write the opposite implementation - the bloody enterprise. And, you know, both are legit.
But the main issue - the code itself. A simple react application could easily bypass "recommended" 250kb. And you might spend a month optimizing it and make it smaller. "Small" optimizations are well documented and quite useful - just get
bundle-analyzer with
size-limit and get back in shape.
There are many libraries, which fight for every byte, trying to keep you in your limits - preact and storeon, to name a few.
But our application is a bit beyond 200kb. It's closer to 100Mb. Removing kilobytes makes no sense. Even removing megabytes makes no sense.
After some moment it's impossible to keep your application small. It will grow bigger in time.
2. Ship less code
Alternatively,
code split. In other words - surrender. Take your 100mb bundle, and make twenty 5mb bundles from it. Honestly - that's the only possible way to handle your application if it got big - create a pack of smaller apps from it.
As long as we're discussing it, you may want to make sure you're up on the latest and greatest when it comes to React code-splitting in 2019. Or just read about some implementation details.
💡 React Code Splitting in 2019
Anton Korzunov ・ Mar 19 ・ 7 min read
But there is one thing you should know right now: whatever option you choose, it's an implementation detail, while we are looking for something more reliable.
The Truth about Code Splitting
The truth about code splitting is that it's nature is TIME SEPARATION. You are not just splitting your code, you are splitting it in a way where you will use as little as possible in a single point of time.
Just don't ship the code you don't need right now. Get rid of it.
Easy to say, hard to do. I have a few heavy, but not adequately split applications, where any page loads like 50% of everything. Sometimes
code splitting becomes
code separation, I mean - you may move the code to the different chunks, but still, use it all. Recall that "Just don't ship the code you don't need right now",– I needed 50% of the code, and that was the real problem.
Sometimes just adding
importhere and there is not enough. Till it is not time separation, but only space separation - it does not matter at all.
There are 3 common ways to code split:
- Just dynamic
import. Barely used alone these days. It's more about issues with tracking a state.
LazyComponent, when you might postpone rendering and loading of a React Component. Probably 90% of "react code splitting" these days.
- Lazy
Library, which is actually
.1, but you will be given a library code via React render props. Implemented in react-imported-component and loadable-components. Quite useful, but not well known.
Component Level Code Splitting
This one is the most popular. As a per-route code splitting, or per-component code splitting. It's not so easy to do it and maintain good perceptual results as a result. It's death from
Flash of Loading Content.
The good techniques are:
- load
js chunkand
datafor a route in parallel.
- use a
skeletonto display something similar to the page before the page load (like Facebook).
prefetchchunks, you may even use guess-js for a better prediction.
- use some delays, loading indicators,
animationsand
Suspense(in the future) to soften transitions.
And, you know, that's all about perceptual performance.
Image from Improved UX with Ghost Elements
That doesn't sound good
You know, I could call myself an expert in code splitting - but I have my own failures.
Sometimes I could fail to reduce the bundle size. Sometimes I could fail to improve resulting performance, as long as
the _more_ code-splitting you are introducing - the more you spatially split your page - the more time you need to _reassemble_ your page back*. It's called a loading waves.
- without SSR or pre-rendering. Proper SSR is a game-changer at this moment.
Last week I got two failures:
- I've lost in one library comparison, as long as my library was better 😉, but MUCH bigger than another one. I have failed to "1. Write less code".
- optimize a small site, made in React by my wife. It was using route-based component splitting, but the
headerand
footerwere kept in the main bundle to make transitions more "acceptable". Just a few things, tightly coupled with each other skyrocketed bundle side up to 320kb(before gzip). There was nothing important, and nothing I could really remove. A death by a thousand cuts. I have failed to Ship less code.
React-Domwas 20%,
core-jswas 10%,
react-router,
jsLingui,
react-powerplug... 20% of own code... We are already done.
The solution
I've started to think about how to solve my problem, and why common solutions are not working properly for my use case.
What did I do? I've listed all crucial location, without which application would not work at all, and tried to understand why I have the rest.
It was a surprise me - the problem was in CSS. In vanilla CSS transition I've used for a smoother UI, and the way I implemented it. Long story short - an underlying DOM node has to exist before transition animation.
Here is the code
- a control variable -
componentControl, eventually would be set to something
DisplayDatashould display.
- once value is set -
DisplayDatabecome visible, changing
className, thus triggering fancy transition. Simultaneusly
FocusLockbecome active making
DisplayDataa modal.
<FocusLock enabled={componentControl.value} // ^ initially it's "disabled". And when it's disabled - it's dead. > {componentControl.value && <PageTitle title={componentControl.value.title}/>} // ^ it's does not exists. Dead-dead <DisplayData data={componentControl.value} visible={componentControl.value !== null} // ^ would change a className basing on visible state /> // ^ that is just not visible, but EXISTS </FocusLock>
I would like to code split this piece as a whole, but this is something I cannot do, due to two reasons:
- the information should be visible immediately, once required, without any delay. A business requirement. So it's better not to code split information.
- the information "skeleton" should exist before, to property handle CSS transition.
This problem could be partially solved using CSSTransitionGroup or recondition - first create hidden, then apply a visible classname - but, you know, fixing one code adding another code sounds weird, even if actually enought. I mean adding more code could help in removing even more code. But... but...
There should be a better way!
TL;DR - there are two key points here:
DisplayDatahas to be mounted, and exists in the DOM prior.
FocusLockshould also exist prior, to contain
DisplayData, but it's brains are not needed in the beginning.
So let's change our mental model
Batman and Robin
Let assume that our code is Batman and Robin. Batman can handle most the bad guys, but when he can't, his sidekick Robin comes to the rescue..
Once again Batman would engage the battle, Robin will arrive later.
This is Batman:
+<FocusLock - enabled={componentControl.value} +> - {componentControl.value && <PageTitle title={componentControl.value.title}/>} + <DisplayData + data={componentControl.value} + visible={componentControl.value !== null} + /> +</FocusLock>
This is his sidekick, Robin::
-<FocusLock + enabled={componentControl.value} -> + {componentControl.value && <PageTitle title={componentControl.value.title}/>} - <DisplayData - data={componentControl.value} - visible={componentControl.value !== null} - /> -</FocusLock>
Batman and Robin could form a TEAM, but they actually, are two different persons.
And don't forget - we are still talking about code splitting. And, in terms of code splitting, where is the sidekick? Where is Robin?
in a sidecar. Robin is waiting in a sidecar chunk.
Sidecar
Batmanhere is all visual stuff your customer must see as soon as possible. Ideally instantly.
Robinhere is all logic, and fancy interactive features, which may be available a second after, but not in the very beginning.
It would be better to call this a vertical code splitting where code branches exist in a parallel, in opposite to a common horizontal code splitting where code branches are cut.
- in some lands, this trio was known as
replace reduceror other ways to lazy load redux logic and side effects as they needed.
- in some other lands, it is known as
"3 Phased" code splitting.
It's just another separation of concerns, applicable only to cases, where you can defer loading some part of a component, but not another part.
image from Building the New facebook.com with React, GraphQL and Relay, where
importForInteractions, or
importAfterare the
sidecar.
And there is an interesting observation - while
Batman is more valuable for a customer, as long as it's something customer might see, he is always in shape (and has a secret abs)... While
Robin, you know, he might be a bit overweight, and require much more bytes for living.
As a result - Batman alone is something much be bearable for a customer - he provides more value at a lower cost. You are my hero Bat!
What could be moved to a sidecar:
- majority of
useEffect,
componentDidMountand friends.
- like all Modal effects. Ie
focusand
scrolllocks. You might first display a modal, and only then make Modal modal, ie "lock" customer's attention.
- Custom
Selects- they are naturally split into Batman(Input) and Robin(Dropdrown). Custom
Calendarsor any other UI component with displays another (the biggest and most complex) part or click/hover - are the same.
- Forms. Move all logic and validations to a sidecar, and block form submission until that logic is loaded. The customer could start filling the form, not knowing that it's only
Batman.
- Some animations. A whole
react-springin my case.
- Some visual stuff. Like Custom scrollbars, which might display fancy scroll-bars a second later. 🤷♂️ Designers 🤷♂️
Also, don't forget - Every piece of code, offloaded to a sidecar, also offload things like core-js poly- and ponyfills, used by the removed code.
Code Splitting can be smarter than it is in our apps today. We must realize there is 2 kinds of code to split: 1) visual aspects 2) interactive aspects. The latter can come a few moments later.
Sidecar makes it seamless to split the two tasks, giving the perception that everything loaded faster. And it will.
The oldest way to code split
While it may still not be quite clear when and what a
sidecar is, I'll give a simple explanation:
Sidecaris ALL YOUR SCRIPTS. Sidecar is the way we codesplit before all that frontend stuff we got today.
I am talking about Server Side Rendering(SSR), or just plain HTML, we all were used to just yesterday.
Sidecar makes things as easy as they used to be when pages contained HTML and logic lived separately in embeddable external scripts (separation of concerns).
We had HTML, plus CSS, plus some scripts inlined, plus the rest of the scripts extracted to a
.js files.
HTML+
CSS+
inlined-js was
Batman, while external scripts were
Robin, and the site was able to function without Robin, and, honestly, partially without Batman (he will continue the fight with both legs(inlined scripts) broken). That was just yesterday, and many "non modern and cool" sites are the same today.
If your application supports SSR - try to disable js and make it work without it. Then it would be clear what could be moved to a sidecar.
If your application is a client-side only SPA - try to imagine how it would work, if SSR existed.
For example - theurge.com, written in React, is fully functional without any js enabled.
There is a lot of things you may offload to a sidecar. For example:
displaycomments, but not
answer, as long as it might require more code(including WYSIWYG editor), which is not required initially. It's better to delay a commenting box, or even just hide code loading behind animation, than delay a whole page.
- video player. Ship "video" without "controls". Load them a second later, the customer might try to interact with it.
- image gallery, like
slick. It's not a big deal to draw it, but much harder to animate and manage. It's clear what could be moved to a sidecar.
Just think what is essential for your application, and what is not quite...
Implementation details
(DI) Component code splitting
The simplest form of
sidecar is easy to implement - just move everything to a sub-component, you may code split using an "old" ways. It's almost a separation between Smart and Dumb components, but this time Smart is not contaniting a Dumb one - it's opposite.
const SmartComponent = React.lazy( () => import('./SmartComponent')); class DumbComponent extends React.Component { render() { return ( <React.Fragment> <SmartComponent ref={this} /> // <-- move smart one inside <TheActualMarkup /> // <-- the "real" stuff is here </React.Fragment> } }
That also requires moving initialization code to a Dumb one, but you are still able to code-split the heaviest part of a code.
Can you see a
parallelor
verticalcode-splitting pattern now?
useSidecar
Building the New facebook.com with React, GraphQL and Relay, I've already mentioned here, had a concept of
loadAfter or
importForInteractivity, which is quite alike sidecar concept.
In the same time, I would not recommend creating something like
useSidecar as long you might intentionally try to use
hooks inside, but code splitting in this form would break rule of hooks.
Please prefer a more declarative component way. And you might use
hooks inside
SideCar component.
const Controller = React.lazy( () => import('./Controller')); const DumbComponent = () => { const ref = useRef(); const state = useState(); return ( <> <Controller componentRef={ref} state={state} /> <TheRealStuff ref={ref} state={state[0]} /> </> ) }
Prefetching
Dont forget - you might use loading priority hinting to preload or prefetch
sidecar and make it shipping more transparent and invisible.
Important stuff - prefetching scripts would load it via network, but not execute (and spend CPU) unless it actually required.
SSR
Unlike normal code-splitting, no special action is required for SSR.
Sidecar might not be a part of the SSR process and not required before
hydration step. It's could be postponed "by design".
Thus - feel free to use
React.lazy(ideally something without
Suspense, you don't need any failback(loading) indicators here), or any other library, with, but better without SSR support to skip sidecar chunks during SSR process.
The bad parts
But there are a few bad parts of this idea
Batman is not a production name
While
Batman/
Robin might be a good mind concept, and
sidecar is a perfect match for the technology itself - there is no "good" name for the
maincar. There is no such thing as a
maincar, and obviously
Batman,
Lonely Wolf,
Solitude,
Driver and
Solo shall not be used to name a non-a-sidecar part.
Facebook have used
display and
interactivity, and that might be the best option for all of us.
If you have a good name for me - leave it in the comments
Tree shaking
It's more about the separation of concerns from bundler point of view. Let's imagine you have
Batman and
Robin. And
stuff.js
export * from `./batman.js` export * from `./robin.js`
Then you might try component based code splitting to implement a sidecar
//main.js import {batman} from './stuff.js' const Robin = React.lazy( () => import('./sidecar.js')); export const Component = () => ( <> <Robin /> // sidecar <Batman /> // main content </> ) // and sidecar.js... that's another chunk as long as we `import` it import {robin} from './stuff.js' .....
In short - the code above would work, but will not do "the job".
- if you are using only
batmanfrom
stuff.js- tree shaking would keep only it.
- if you are using only
robinfrom
stuff.js- tree shaking would keep only it.
- but if you are using both, even in different chunks - both will be bundled in a first occurrence of
stuff.js, ie the main bundle.
Tree shaking is not code-splitting friendly. You have to separate concerns by files.
Un-import
Another thing, forgotten by everybody, is the cost of javascript. It was quite common in the jQuery era, the era of
jsonp payload to load the script(with
json payload), get the payload, and remove the script.
Nowadays we all
importscript, and it will be forever imported, even if no longer needed.
As I said before - there is too much JS, and sooner or later, with continuous navigation you will load all of it. We should find a way to un-import no longer need chunk, clearing all internal caches and freeing memory to make web more reliable, and not to crush application with out of memory exceptions.
Probably the ability to
un-import (webpack could do it) is one of the reasons we should stick with component-based API, as long as it gives us an ability to handle
unmount.
So far - ESM modules standards have nothing about stuff like this - nor about cache control, nor about reversing import action.
Creating a sidecar-enabled Library
By today there is only one way to create a
sidecar-enabled library:
- split your component into parts
- expose a
mainpart and
connectedpart(not to break API) via
index
- expose a
sidecarvia a separated entry point.
- in the target code - import the
mainpart and the
sidecar- tree shaking should cut a
connectedpart.
This time tree shaking should work properly, and the only problem - is how to name the
main part.
//main.js export const Main = ({sidecar, ...props}) => ( <div> {sidecar} .... </div> ); // connected.js import Main from './Component'; import Sidecar from './Sidecar'; export const Connected = props => ( <Main sidecar={<Sidecar />} {...props} /> ); //index.js export * from './Main'; export * from './Connected'; //sidecar.js import * from './Sidecar'; // ------------------------- //your app BEFORE import {Connected} from 'library'; // // ------------------------- //your app AFTER, compare to `connected.js` import {Main} from 'library'; const Sidecar = React.lazy(import( () => import('library/sidecar'))); // ^ all the difference ^ export SideConnected = props => ( <Main sidecar={<Sidecar />} {...props} /> ); // ^ you will load only Main, Sidecar will arrive later.
Theoretically
dynamic import could be used inside node_modules, making assemble process more transparent.
Anyway - it's nothing more than
children/
slotpattern, so common in React.
The Final Form
With all the principles listed above the final
sidecar form is:
import {Main} from 'library'; const Sidecar = React.lazy(import(/* webpackPrefetch: true */ () => import('library/sidecar'))); export SideConnected = ({enabled, props}) => ( <Main sidecar={enabled && <Sidecar />} {...props} /> );
It prefetches sidecar chunk and uses not when component just "used", but when it used in a "active" form (if that form exists).
Without extraction of "active form" sidecar would improve Time-To-Render, separating it from Time-To-Interactive, keeping the second a bit delayed as long as "interactivity" would be loaded by
the main bundle itself.
This "a bit" could be a whole time required to load main chunk and render your application for the first time.
Keep in mind - extracting small "cars", required just after initial rendering could be not the best idea. In my case I was able to "extract" almost 70% of the code greatly improving Time-To-Render.
The future
Right now it requires some code changes to be applied to your codebase. It requires a more explicit separation of concerns to actually separate them, and let of codesplit not horizontally, but vertically, shipping lesser code for a bigger user experience.
Sidecar, probably, is the only way, except old school SSR, to handle BIG code bases. Last chance to ship a minimal amount of code, when you have a lot of it.
It could make a BIG application smaller, and a SMALL application even smaller.
10 years ago the medium website was "ready" in 300ms, and was really ready a few milliseconds after. Today seconds and even more than 10 seconds are the common numbers. What a shame.
Let's take a pause, and think - how we could solve the problem, and make UX great again...
Overall
sidecar provides time and/or space separation. You can
import all scripts you need a bit later... a bit later using dynamic import, or you can
require them, when you need them. In the second time you will make things simpler, and more synchornios but still be able to save some initial bundle starting time, deferring modules evaluation example.
// time and space separation const ImportSidecar = sidecar( () => import("./sidecar")); export function ComponentCombination(props) { return ( <ComponentUI {...props} sideCar={RequireSideCar} /> ); } // only time separation const RequireSideCar = (props: any) => { const SideCar = require('./sidecar').default; return <SideCar {...props} />; }; export function ComponentCombination(props) { return ( <ComponentUI {...props} sideCar={RequireSideCar} /> ); }
- 1. Component code splitting is a most powerful tool, giving you the ability to completely split something, but it comes with a cost - you might not display anything except a blank page, or a skeleton for a while. That's a horizontal separation.
- 2. Library code-splitting could help when component splitting would not. That's a horizontal separation.
- 3. Code, offloaded to a sidecar would complete the picture, and may let you provide a far better user experience. But would also require some engineering effort. That's a vertical separation.
Let's have a conversation about this.
Stop! So what about the problems you tried to solve?
react-focus-lock, react-focus-on and react-remove-scroll have implemeneted this pattern.
Well, that was only the first part. We are in the endgame now, it would take a few more weeks to write down the second part of this proposal. Meanwhile...
Discussion
In your last example why do you load
library/sidecarlazily but in your library use it as a static import?
Not really fully on that boat yet, great article by the way. Love reading your articles since every concept has a well-defined example attached to it.
It was more about:
Thingfrom your library
thingto
Mainand
Sidecar
Main, just the one part, and the old
Thingassembled back from new pieces. Library public API is not changed. This is no more than a minor bump.
Sidecarvia another endpoint
Thingin a user space from
Mainand lazy
Sidecar.
Technically you may keep
importin a library code, but you will loose control on chunk name and prefetching.
As I said - this is a subject to complete and argue about.
Amazing read! 👏 Thanks Anton! 💯 | https://dev.to/thekashey/sidecar-for-a-code-splitting-1o8g | CC-MAIN-2020-50 | refinedweb | 3,892 | 66.64 |
Thu, 05/10/2007 - 17:35
Forums:
Hi
I am new to opencascade. I want to know how do create texture that has image display as background and another special thing i want to do is some pixel operation in current texture set.
I am want some pixel buffer in texture and update in some interval time...
Can anyone tell me how to do this stuff. ?
I have already done with OpenGL without OpenCasCade via glTexImage2D or glTexSubImage2D method.
Alex
Tue, 05/15/2007 - 22:43
Hi,
To set texture image as background in OpenCASCADE you simply need to call the method
myView->SetBackgroundImage("background.bmp", Aspect_FM_STRETCH, true);
where myView is Handle(V3d_View) and background.bmp is a bitmap image you want to display as background.
Can you please tell me how to display background image in OpenGL using texture? I want to use the technique to display gradient background in OpenGL. Please send the detailed code.
Regards
N. Sharjith
Thu, 05/17/2007 - 23:47
The secret to getting a gradient background seems to be two-fold. This is the outline of the solution.
First you need to have your own rendering context which you can draw onto. You need to "offer" this context to OCC as its rendering context. Next you need to register a call-back function for the viewer, which is called in the OCC render process just before the buffers are swapped. This is accomplished using the alternative SetWindow method, which enables you to set both an exising rendering context and call-back function.
In my case the first part is relatively easy (well it is on XP). My rendering context can be grabbed directly from the Qt QGLWidget. The real call-back function paintOCC()is hooked by a static member function to emulate the objects "this" pointer. The paintOCC() just issues OpenGL calls, and I've just set up a GL_QUAD with a gradient that I can paint at the far depth point by setting up glOrtho projection, but I guess it could run any open gl command, texture etc.. I do need a specific line of code in the normal #ifdef WNT code to get the HGLRC and I'm not able to test the Linux X11 equivalent.
The gotcha so far is that by default I paint a grid onto my widget on the privelege plane. When I have an AIS object on screen, this looks great with a nice gradient background, but with no object the background quad seems to cover the grid. It looks like the state of the blending function is different between these two conditions, and I have blended the backgound to see the grid, but the blending effect changes as soon as load the test bottle which isn't nice.
I'm going to have a hack around to see if I can see where the difference comes from i the OCC code, then I'll put up my code for you to see - its easier to read than explain. If anyone can live without this nicety, reply here and I'll make available anyway - the effect does look quite nice!
If anyone else has tried this method and come up with a solution, please tell me how.
Pete
Fri, 05/18/2007 - 19:11
Sorry Gues
I was not able to check messages...About Dolbey Please can post codes. ??
About OpenGL my code that does pixel operation is here but keep in mind these operation could be done in withthin begin scene and end scene (swap buffer)..
glEnable(GL_TEXTURE_2D);
glGenTextures(1, &video_texture);
glBindTexture(GL_TEXTURE_2D, video_texture);
BYTE* black_frame = (BYTE*)malloc(width*height*4*sizeof(BYTE));
memset(black_frame, 0, width*height*4*sizeof(BYTE));
glTexImage2D(GL_TEXTURE_2D, 0, 4, width, height, 0,
GL_BGRA_EXT, GL_UNSIGNED_BYTE, black_frame);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_CLAMP);
free(black_frame);
Fri, 05/18/2007 - 21:12
Hi
Sorry to trouble you again.But I didnot get what you said... "About OpenGL my code that does pixel operation is here but keep in mind these operation could be done in withthin begin scene and end scene (swap buffer).."
Can you please send me a sample code in opengl with gradient or texture background, as you have done it, to my mail id: sharjith@gmail.com
Thanks in anticipation.
Reards
N. Sharjith
Mon, 05/21/2007 - 16:21
They say give a man a fish and he will feed himself for a day; give him a fishing net and he'll feed himself for life.
I'm not just going to put my code on the web for download just yet for 2 reasons.
1. It doesn't work properly yet (as per my previous hastily written post).
2. It won't explain the basis of the solution.
Somewhere around OCC version 5, an alternate form of the SetWindow call was introduced into the API. Its documented in the Visual3d_View.cdl as
SetWindow ( me : mutable;
AWindow : Window from Aspect;
AContext: RenderingContext from Aspect;
ADisplayCB: GraphicCallbackProc from Aspect;
AClientData: Address from Standard
)
---Level: Public
---Purpose: Associates the window and context
-- to the view .
-- If is not NULL the graphic context is used
-- directly to draw something in this view.
-- Otherwise an internal context is created.
-- If is not NULL then a user display CB is
-- call at the end of the OCC graphic traversal and just
-- before the swap of buffers. The is pass
-- to this call back.
-- No new association if the window is already defined.
-- Category: Methods to modify the class definition
-- Warning: Raises ViewDefinitionError if it is impossible
-- to associate a view and a window.
-- (association already done or another problem)
-- Modifies the viewmapping of the associated view
-- when it calls the SetRatio method.
raises ViewDefinitionError from Visual3d is static;
---Purpose:
-- After this call, each view is mapped in an unique window.
In the Windows world, the Aspect_RenderingContex is a direct map to the HGLRC. This enables you re-use an existing OpenGL rendering context - but the function does execute another choosePixelFormat on Windows when called. In the Qt world this means you can actually re-use the OpenGL context within the QGLWidget. However you can provide the function with a zero value for AContext, in which case the viewer will construct its own rendering context as normal.
The function also enables you to register a callback procedure that will be called in the OCC rendering loop just before the final call to swapbuffers, irrespective of which rendering context you provide - the makeCurrent will already be called. For the interested, you can see the call back function being called in "call_togl_redraw" in opengl_togl_redraw.c.
The call back function itself need to math the prototype
int foo (Aspect_Drawable drawable, void* aPointer, Aspect_GraphicCallbackStruct* data)
This cannot be implemenented as a directly as class member function because it doesn't contain the magic "this" pointer. However it can be implemented a static class function, and we can implement the this pointer via the void* aPointer. The Aspect_Drawable contains some stuff that mignt be useful but for now I've just implemented it to provide the necessary padding.
The following segments are based on my QtOCC implementation (v0.6) but should be applicable to any presentation viewer framework.
First create 2 function prototypes in your header file - I've used the following in QtOCCViewWidget.h
static int CallBack (Aspect_Drawable, void*, Aspect_GraphicCallbackStruct*);
and
void paintOCC();
(Note I originally used paintGL() instead of paintOCC() but this resulted in both OCC and Qt calling the method)
To register the call back, I changed the initialize() method to read
#ifdef WNT
HGLRC rc = wglGetCurrentContext();
myWindow = new WNT_Window( Handle(Graphic3d_WNTGraphicDevice)
::DownCast(myContext->CurrentViewer()->Device() ), (int)hi, (int)lo);
myView->SetWindow( myWindow, rc , CallBack, this );
#else
myWindow = new Xw_Window( Handle(Graphic3d_GraphicDevice)
::DownCast(myContext->CurrentViewer()->Device() ), (int)hi, (int) lo,
Xw_WQ_SAMEQUALITY,
Quantity_NOC_BLACK);
myView->SetWindow( myWindow );
#endif // WNT
// Set my window (Hwnd) into the OCC view
// myView->SetWindow( myWindow );
Note that I'm only affecting the Windows (WNT) version here. If you just use HGLRC rc = 0 then OCC creates the rendering context but still registers the call back.
The line "myView->SetWindow( myWindow, rc , CallBack, this);" registers the Callback function and passes the objects "this" pointers as the Aspect_GraphicCallbackStruct*.
Next I implement the callback routine in the class implementation. This routine has access to all the class members and methods but is not bound to a specific object instance. Here's the implemenation
int QtOCCViewWidget::CallBack (Aspect_Drawable drawable,
void* aPointer,
Aspect_GraphicCallbackStruct* data)
{
QtOCCViewWidget *aWidget = (QtOCCViewWidget *) aPointer;
aWidget->paintOCC();
return 0;
}
Finally I implement the paintOCC() routine - this is where the OpenGL gurus can start practising their skills. By default objects you draw here will be placed in the current OCC world space. To get a gradient background however I remap the screen to a bi-unit cube with a glOrtho, clamping the depth buffer from z=1 to z=-1 and place a GL_QUAD with a greyish gradient. Here's my current implementation.
void QtOCCViewWidget::paintOCC()
{
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1.0, 1.0, -1.0, 1.0, 1.0, -1.0);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE) ;
glShadeModel(GL_SMOOTH);
//glDisable(GL_LIGHTING);
glBegin(GL_QUADS);
{
glColor4f(0.1, 0.1, 0.1, 1.0);
glVertex3d( -1.0, -1.0, 1.0);
glVertex3d( 1.0, -1.0, 1.0);
glColor4f(0.9, 0.9, 0.9, 1.0);
glVertex3d( 1.0, 1.0, 1.0);
glVertex3d( -1.0, 1.0, 1.0);
}
glEnd();
}
(Another note - still not sure whether my glOrtho is correct yet, but it works!)
That should be pretty much it, except (as you can see from the glBlendFunc) I'm finding a problem, probably in the alpha colour components where the state of the rendering context id different with and without a AIS_Shape being drawn thats affect rendering of my grids. I've enabled debugging in the OCC openGL code and I am wading through GLIntercept logs to see if I can identify a fix.
Hope this makes sense. Any comments are gratefully received.
Enjoy
Pete
Tue, 05/22/2007 - 11:48
Apart from the obvious typos (math should read match, mignt should read might and so on, the line "However it can be implemented a static class function, and we can implement the this pointer via the void* aPointer" should read "However it can be implemented a static class function, and we can implement the this pointer via the Aspect_GraphicCallbackStruct* data pointer). Oh, for an edit function.
Pete
Tue, 05/22/2007 - 12:39
Hi Pete,
first of all thanks for the post. It's a really nice functionality anebling to access the OpenGL layer. Once again - a big thanks!
I've implemented the rendering in my app and it seems to work fine. The only thing I had to modify was to use a static variable to use the HGLRC (I have an MDI app).
Greets
Pawel
Tue, 05/22/2007 - 12:51
I hope you mean "non-static" class member otherwise you'll only have one rc shared across all windows in the class.
Anyway, great news.
Pete
Tue, 05/22/2007 - 19:02
Hi Pete,
no I mean static. I'm not an OpenGL expert but I've googled a bit and found actually three possible ways of creating the rendering context:
1) in SDI applications - created during the initilization and then deleted with wglDeleteContext when the application closes ()
2) in OnPaint method ()
3) as static variable ()
Besides my application crashes if I create a separate rendering context for each of my document windows.
Pawel
Tue, 05/22/2007 - 22:00
Tue, 05/22/2007 - 22:09
Wed, 05/23/2007 - 12:18
Hi Pete,
this is my code:
//header
class OCCViewer
{
public:
private:
Handle_V3d_Viewer myViewer;
Handle_V3d_View myView;
Handle_AIS_InteractiveContext myAISContext;
Handle_Graphic3d_WNTGraphicDevice myGraphicDevice;
static HGLRC rc;
bool useDirectOpenGLRendering;
public:
static int CallBack (Aspect_Drawable ,void* ,Aspect_GraphicCallbackStruct*);
void PaintOCC();
static CCriticalSection g_cs;
...
}
//implementation
CCriticalSection OCCViewer::g_cs;
HGLRC OCCViewer::rc = wglGetCurrentContext();
/// OpenGL rendering function.
void OCCViewer::SetOpenGLRendering(bool directOpenGLRendering)
{
useDirectOpenGLRendering = directOpenGLRendering;
}
/// OpenGL rendering function.
void OCCViewer::PaintOCC()
{
if(useDirectOpenGLRendering == true)
{
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1.0, 1.0, -1.0, 1.0, 1.0, -1.0);
glEnable(GL_BLEND);
glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_COLOR);
glShadeModel(GL_SMOOTH);
glBegin(GL_QUADS);
{
glColor4f(0.0f, 0.0f, 0.0f, 0.8f);
glVertex3d( -1.0, -1.0, 1.0);
glVertex3d( 1.0, -1.0, 1.0);
glColor4f(0.7f, 0.7f, 0.7f, 0.8f);
glVertex3d( 1.0, 1.0, 1.0);
glVertex3d( -1.0, 1.0, 1.0);
}
glEnd();
}
}
/// User rendering callback function.
int OCCViewer::CallBack(Aspect_Drawable drawable,
void* aPointer,
Aspect_GraphicCallbackStruct* data)
{
g_cs.Lock();
OCCViewer *viewer = (OCCViewer *) aPointer;
if(viewer != NULL)
viewer->PaintOCC();
else
TraceWarning("OCCViewer Error. CallBack - viewer Null pointer.");
g_cs.Unlock();
return 0;
}
bool OCCViewer::InitViewer(void* wnd)
{
/*if ( myGraphicDevice.IsNull() )
{*/
try {
myGraphicDevice = new Graphic3d_WNTGraphicDevice();
} catch (Standard_Failure) {
return false;
}
/*}*/
TCollection_ExtendedString a3DName("Visu3D");
myViewer = new V3d_Viewer( myGraphicDevice, a3DName.ToExtString(),"", 1000.0,
V3d_XposYnegZpos, Quantity_NOC_BLACK,
V3d_ZBUFFER,V3d_GOURAUD,V3d_WAIT,
Standard_True, Standard_False);
myViewer->Init();
myViewer->SetDefaultLights();
myViewer->SetLightOn();
myView = myViewer->CreateView();
Handle(WNT_Window) aWNTWindow = new WNT_Window(myGraphicDevice, reinterpret_cast (wnd));
myView->SetWindow(aWNTWindow, rc, (&OCCViewer::CallBack), this);
//myView->SetWindow(aWNTWindow);
if (!aWNTWindow->IsMapped())
aWNTWindow->Map();
myAISContext = new AIS_InteractiveContext(myViewer);
myAISContext->UpdateCurrentViewer();
myView->Redraw();
myView->MustBeResized();
// TRIHEDRON
Handle(AIS_Trihedron) aTrihedron;
Handle(Geom_Axis2Placement) aTrihedronAxis=new Geom_Axis2Placement(gp::XOY());
aTrihedron=new AIS_Trihedron(aTrihedronAxis);
aTrihedron->UnsetSelectionMode();
myAISContext->Display(aTrihedron);
//static TRIHEDRON - not sizable, not movable
myView->TriedronDisplay(Aspect_TOTP_RIGHT_UPPER,Quantity_NOC_GREENYELLOW,0.05);
return true;
}
This code works fine. If I make HGLRC non-static and initialize it in OCCViewer::InitViewer the app generates exceptions after I've closed a viewer window (with multiple windows open).
I also tried to use the non-static HGLRC in an MFC MDI app, and make it current like this:
PaintOCC()
{
CDC* cdc = GetWindowDC();
HDC hdc = cdc->GetSafeHdc();
wglMakeCurrent(hdc, rc);
...
ReleaseDC(cdc);
}
The effects are similar to the ones described above (after I've closed the viewer created at first there's no rendering in the remaining ones).
Pawel
Wed, 05/23/2007 - 21:44
Sorry Pawel but thats a bit "screwy".
Your code line
HGLRC OCCViewer::rc = wglGetCurrentContext();
is being called as an intialisation even before you've hit the main/WinMain routine, abd certainly before you've created any windows, HWNDs or HDCs. Debugging it reveals that its effectively just acting like
HGLRC OCCViewer::rc = 0;
If your running in debug mode, just place a breakpoint on this line, or watch the value of the rc in your view constructor.
The reason your code works when you use a static variable is because when pass rc into setWindow, OCC uses the value of 0 to determine whether to create its own OpenGL rendering context or not. Actually, unless you want add the code to create the rc (choosePixelFormat etc) for some other reason, you might as well leave it this way and leave it up to OCC to create the context. The examples on Nehe's site give a statring pint for this. You can still exploit the callback routine this way. In my Qt code, the QGLWidget has already set up a rendering context and my reason for tying to re-use is to reduce the total number of system resources used.
If you want me to look at setting up a rendering context in MFC that can be shared by OCC, you might need to send me a simplifed version of your code + project files (peter @ dolbey dot freeserve dot co uk) - its been a long since I've coded OpenFL MFC progs, but I still have plenty of examples in the archives. However, in practice you might just as well remove all references to your static rc and just pass a constant zero value in setWindow - it looks like your "cheapest" option!
I'm also not convinced about having a global CriticalSection. I don't see anyway that your viewer will recieve multiple paint events from the single GUI thread - the paint events are inherently queued in the window message loop. You should be able to remove the g_cs lock/unlock as well as the rc - this is not needed anymore as a shared resource.
I see you've been having a play with the blending function - I'll see what this does in my own code.
However when the gradients running in the background, it does give a nice effect doesn't it - have you tried different colours on the quad's corners yet?
Cheers
Pete
Sat, 05/26/2007 - 14:16
Strange things happen with this gradient background technique if you don't display a Triedron i.e. you only get the gradient background if an object is selected under the mouse. This is of course totally "screwy" and to be honest I don't know how to fix it without taking the whole rendering engine apart.
So for now, you need to keep a Triedron displayed for the callback to work.
Pete
Mon, 05/28/2007 - 21:32
For anyone monitoring my attempts to get a "reliable" gradient background just using OpenGL calls, I have discovered solutions to both of my current problems.
The trihedron code was causing the lights to be turned off in all cases, whereas without the the trihedron being dispayed, the state of the lighting dependened on whether the shape was highlighed. A simple fix is to add a "glDisable (GL_LIGHTING);" int the callback routine.
void QtOCCViewWidget::paintOCC()
{
glDisable(GL_LIGHTING); //left on by trihedron
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glMatrixMode(GL_PROJECTION);
glLoadIdentity();();
}
Notice all the blending has now been removed. The original problem I had was down to OCC trying to optimize the depth buffers - i.e. it did not perform depth sorting unless there were some faces to sort. This "feature" has to be switched off - it can be done when the viewer is created in my QtOCCViewerContext() constructor
.
myViewer->Init();
myViewer->SetZBufferManagment(Standard_False);
myViewer->SetDefaultLights();
myViewer->SetLightOn();
.
- its the "myViewer->SetZBufferManagment(Standard_False);" that does the job.
This code is now probably stable enough to merit a new downloadable sample, but I will only do that if interest is shown on this thread as it takes up space from my web allowance.
Pete
Tue, 05/29/2007 - 11:55
Hi Pete,
I've looked at the code again and have some comments.
For some reason my HGLRC equals 0. I can't figure it out so for now I guess I'll leave creating the context to OC.
I used critical sections because I have can have access to my viewer from multiple threads - it's application specific. But I agree, maybe this should not be global. I'll look at that.
Your solution of the problem with the lights works well. However, removing the blending from the rendering function has a drawback. The color scale - myView->ColorScaleDisplay() - (if you have one) is not displayed anymore.
These are some observations I've made (unfortunately not many solutions :( )
Thanks again for your efforts.
Pawel
Tue, 05/29/2007 - 12:16
Pawel
These replies are getting awfully compressed to the right of the page .
I explained the reason for the HGLRC coming out as zero two posts up. You're basically initialising it before you've initialised OpenGL, or anything else come to that. As I said in that post, you might as well leave the context creation to OCC - but you've come to this conclusion on your own. From the thread perpespecive, both MFC and Qt use a single thread for their GUIs, and although there is some clever stuff around for multi-threading OpenGL but I didn't see that in your code.
I basically had a fun week-end drilling through rendering logs. If you're on a XP/Win32 platform grab a copy of GLintercept from
(and use a the patched OpenGL32.dll in a separate folder and don't overwrite the one in system32). I've found it an powerful tool for trying to understand the OCC rendering process. I managed to find to fixes for the background gradient, point markers, and rediscovered the flicker fix given in
that I had forgottent to apply to OCC 6.2. Obviously I haven't tried to fix a problem that I haven't experienced yet i.e. ColorScaleDisplay but my offer still stands - post a simplified version of your code that exhibits the problem to "peter at dolbey dot freeserve dot co dot uk" and I'll take a look at it - with no absolutely guarantee of success.
Pete
Tue, 05/29/2007 - 23:44
And squeezing into the corner...
I see what you mean about ColorScaleDisplay. Best results (near perfect) I've got so far are with
glBlendFunc(GL_ONE_MINUS_DST_ALPHA, GL_SRC_ALPHA);
There's another gotcha. If you use a grid echo, i.e. a immediate mode draw you need to glPushMatrix/glPopMatrix both projecttion and modelview matrices (as a "polite" routine should do anyway). Note that having both a ColorScaleDisplay and a grid echo don't work together with the background. Actually they don't workout the gradient either i.e. this an OCC bug.
Cheers
Pete
Wed, 05/30/2007 - 00:31
And looks something like this
And here's my latest callback routine - I think I'll stop here!
void QtOCCViewWidget::paintOCC()
{
glDisable(GL_LIGHTING);
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glEnable(GL_BLEND);
glBlendFunc(GL_ONE_MINUS_DST_ALPHA, GL_SRC_ALPHA);();
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
glPopMatrix();
}
Pete
Fri, 06/01/2007 - 11:58
I've finally found the reason for the crashes in my app. It is actually pretty simple.
The OpenGL context is not available during the viewer initialization and so:
HGLRC rc = wglGetCurrentContext()
returns NULL. However, when I use
myView->SetWindow(aWNTWindow, rc, (&OCCViewer::CallBack), this);
(no matter if rc is static or not) OC takes a reference. This leads to problems during the destruction. So I just took:
myView->SetWindow(aWNTWindow, 0, (&OCCViewer::CallBack), this);
and it works well.
Pawel
Tue, 11/11/2008 - 17:26
hi pawel,
i have used your code, but if the 3d scene objects display mode is set to AIS_Shaded, the gradient is lost -> background color is used.
have you any idea, where is the problem?
adrian
Tue, 11/11/2008 - 17:49
Hi Adrian,
it's been a while since I last looked at the thread... So, what is the code you used exactly? Are you sure you do not interfere somewhere else?
I never had the problem you describe.
I'm still using OC6.2.
Pawel
Wed, 11/12/2008 - 11:34
pawel,
hm, i am using 5.2. can it be a problem?
are you able to compile your code for 5.2, or would you send me a sample project?
adrian
Wed, 11/12/2008 - 11:41
Hello Adrian,
yes I can try compiling with 5.2, but probably not sooner than during the weekend...
Could you please post your e-mail?
Best regards
Pawel
Sat, 05/28/2016 - 11:08
Hello,
My name is Achilles Karfis - Rural and surveyor engineer. I want to use opencascade technology in order to create a cad system.
My question is how to build open cascade in windows and how can I create a simple 2d cad project.
For me its clear that Geom2d is recommended but how about Draw?
How to connect Draw with openGL | https://dev.opencascade.org/content/creating-texture-background-image | CC-MAIN-2021-17 | refinedweb | 3,863 | 53.92 |
IRC log of dawg on 2004-03-25
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agenda + convene, take role, review record, agenda, and misc actions
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agenda + Amsterdam meeting arrangements
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agenda + Use cases and Requirements
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argh, zakim always gets my name wrong
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15:31:01 [DanC]
Zakim, KendalC is KendallC
15:31:01 [Zakim]
+KendallC; got it
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15:33:15 [Zakim]
+??P20
15:33:31 [Zakim]
+Patrick
15:33:36 [DanC]
Zakim, ??P20 is DaveB
15:33:37 [Zakim]
+DaveB; got it
15:33:45 [AndyS]
zakim, ??P13 is AndyS
15:33:48 [alberto]
alberto has joined #dawg
15:33:49 [Zakim]
+AndyS; got it
15:33:55 [DanC]
Zakim, aaaa is RobS
15:33:55 [Zakim]
+RobS; got it
15:34:27 [Zakim]
+Pat_Hayes
15:34:35 [alberto]
alberto has joined #dawg
15:34:41 [DanC]
Zakim, who's on the phone?
15:34:41 [Zakim]
On the phone I see Tayeb, AndyS, RobS, KendallC, +1.317.151.aabb, EricP, [ASemantics], DanC, DanielK, DaveB, Patrick, Pat_Hayes
15:34:43 [Zakim]
[ASemantics] has DirkG
15:35:36 [alberto]
+39 is Alberto Reggiori - on the phone too
15:36:34 [dirkx]
list attendees
15:36:40 [dirkx]
zakim, list attendees
15:36:40 [Zakim]
As of this point the attendees have been Tayeb, +1.760.476.aaaa, +1.317.151.aabb, EricP, KendallC, DirkG, DanC, DanielK, Patrick, DaveB, AndyS, RobS, Pat_Hayes
15:37:09 [Zakim]
+JosD
15:37:32 [DanC]
Zakim, take up item 1
15:37:32 [Zakim]
agendum 1. "convene, take role, review record, agenda, and misc actions
" taken up [from DanC]
15:38:40 [DanC]
Zakim, next item
15:38:40 [Zakim]
agendum 2. "Amsterdam meeting arrangements" taken up [from DanC]
15:38:59 [alberto]
15:39:28 [dirkx]
Details
- will be adding more details as we get closer.
15:39:31 [alberto]
1st f2f meeting in AMS (Leiden actually) - 22-23 April
15:39:33 [ericP]
ACTION ericP: set up meeting registration
15:41:18 [DanC]
Zakim, next item
15:41:18 [Zakim]
agendum 3. "Use cases and Requirements" taken up [from DanC]
15:41:48 [dirkx]
Dirk will follow hotel sitation (please email me if you find them full) and will try to keep up adding additional ones (the current ones where verified on thursday/friday as still having rooms ).
15:41:58 [KendallC]
attendees: alberto asemantics, andyS, jean-francois inria, dank, kc,
15:41:58 [KendallC]
robs, patricks, dajobe, ericp, dancon, jos de roo, pat hayes
15:41:58 [KendallC]
1 april next meeting
15:41:58 [KendallC]
dajobe scribe volunteer
15:41:58 [KendallC]
minutes approved (no opposed, no abstens)
15:42:11 [KendallC]
danc reserved bridge
15:42:11 [KendallC]
amsterdam meeting arrangements, dirk gives us dawg.asemantics.com
15:42:11 [KendallC]
ericp take over registration for f2f
15:42:11 [KendallC]
discuss telcon participation @ f2f
15:42:11 [KendallC]
danc working on f2f agenda
15:42:43 [KendallC]
discuss use cases and requirements
15:43:55 [KendallC]
attendee: dirk asemantics
15:44:48 [KendallC]
m
15:47:16 [KendallC]
m
15:47:19 [KendallC]
argh, sorry
15:47:55 [DaveB]
also attendee, josD - came in during roll call
15:48:04 [DaveB]
oh you caught that, sorry
15:48:08 [KendallC]
thx
15:48:26 [DanC]
KendallC, no need to paste everything from emacs into this log. but if you could start taking notes here now, that might help.
15:49:50 [KendallC]
danc points out that our examples *are* the use cases (maybe clearer to call them user *stories* then?)
15:50:02 [DanC]
"story" is fine by me.
15:52:12 [alberto]
two possible applications/use-cases for "tell me about X": data/metadata browser, metadata crawler
15:52:56 [KendallC]
dirkx: split this use case (tell me about foo) into some specific domains. It's very genric.
15:52:59 [KendallC]
er, generic.
15:53:18 [KendallC]
the google harvesting case, follow the hierarchy case, tell me more case...
15:54:01 [KendallC]
use case: AndyS's "Find the email address of John Smith"
15:54:39 [KendallC]
robs: we should address precisely what the user wants to do with the results of this query.
15:54:55 [dirkx]
Making the use case more specific: "Browse" as in 'discover'; "Browse" as in selectively/interactively follow certain references; "Browse" as in 'discover' more information/refinements; "Browse" as in retrieve some alternative presentation to do something 'different' with.
15:55:12 [KendallC]
dirkx: thx
15:55:37 [KendallC]
andys: the use case *should* say, if it doesn't, that the query returns an email address, not some RDF.
15:55:43 [DanC]
(that's bryanT speaking?)
15:55:46 [dirkx]
I think andy meant that the Use case does -not- say that you get back RDF - rather some result. Such as an email. That is application specific. i read it that way.
15:55:48 [KendallC]
oh, sorry
15:55:53 [dirkx]
Sorry Andy - you just said that I think.
15:56:30 [KendallC]
andys: 2 revisions coming
15:57:11 [KendallC]
danc: does anyone think our tech won't solve this problem? No.
15:57:34 [dirkx]
DanC: it would not solve the whole problem - just be a key element/step in that process.
15:57:35 [rob]
that's white pages, not yellow...
15:57:52 [KendallC]
<strike>No.</strike> :>
15:58:42 [KendallC]
some hints of consensus forming around idea of solving this use case
15:59:05 [JosD]
JosD has joined #dawg
15:59:59 [KendallC]
use case: EricP's use case/action item
16:01:24 [dirkx]
Not sure if 'real-life' sizing our use cases are that useful. In actual reality 80% of any given 'solution' for such a case will have nothing to do with RDF and even less is DAWG scope concerned. So you are building use cases which are out of scope to whcih you may add a postfix listing just that part which is DAWG specific.
16:01:37 [DaveB]
EP-1 doesn't seem to do anything with ?context in the collect
16:01:49 [rob]
I think scope comes second. Use cases come first.
16:02:26 [DanC]
PatrickS tells a story of a vendor with complex parts... wants to put a catalog online...
16:03:26 [rob]
All these "tell me abouts" suddenly seem very interactive and less automated...
16:03:48 [KendallC]
most of our stories seem very human facing, which keeps surprising me
16:04:00 [dirkx]
rob: that is the result of a premisse; that it must be a story understandable to Aunt Mary.
16:04:16 [rob]
I feel that the open-ended "tell me about" is intrisically harder to deal with automatically.
16:05:50 [KendallC]
action item: patricks to write up his car-parts story
16:06:46 [KendallC]
(err, i assume that was a real action item, patrick. if not, lemme know.)
16:07:19 [KendallC]
use case: danc's geo story
16:07:37 [KendallC]
some liking of alberto's (?) proposed solution
16:07:39 [DanC]
"Re: Use case: tiger map/census data: have it your way"
and thread
16:07:46 [KendallC]
thx
16:08:26 [KendallC]
alberto: it can be seen as a case for a kind of extensibility requirement in the QL
16:08:45 [KendallC]
danc: didn't mean it as a story to motivate extensibility
16:09:04 [KendallC]
danc: rather, that some basic maths should be in the QL
16:10:58 [alberto]
exslt is a good example of that i.e. extend XSLT easly with namespace
16:12:08 [alberto]
library like for GIS "operators" for example - or something along those lines
16:12:57 [KendallC]
youch!
16:14:49 [KendallC]
Zakim, mute me
16:14:49 [Zakim]
KendallC should now be muted
16:16:46 [rob]
One of our technologies here at NI involves viewing relational databases as RDF data.
16:18:14 [KendallC]
there's some appeal for danc's geo story
16:18:32 [KendallC]
dajobe: speaks in support of EP1 (is that right?)
16:19:02 [DaveB]
16:20:46 [ericP]
EP-4 aka FatAnnotationQuery:
16:21:20 [alberto]
Andys - isn't that about Annotea and Amaya ?
16:21:20 [ericP]
AndyS, cool use case!
16:22:02 [ericP]
Annotea curently shows what annotaitons there are on the "current" document
16:22:20 [alberto]
ericP: ok one step further - cool
16:22:26 [Zakim]
- +1.317.151.aabb
16:22:28 [ericP]
AndyS's sounds like it shows usefule stuff when hovering
16:23:26 [alberto]
AndyS UC sounds like "inline metadata" case - attach some external metadata to a link/image - interesting
16:23:52 [AndyS]
alberto - I guess so! trying to be a UC, not tech :-)
16:24:03 [rob]
I can stick around.
16:24:07 [alberto]
AndyS - +1 ! :-)
16:24:21 [KendallC]
Zakim, unmute me
16:24:21 [Zakim]
KendallC should no longer be muted
16:25:20 [DanC]
Zakim, who'se here?
16:25:20 [Zakim]
I don't understand your question, DanC.
16:25:24 [DanC]
Zakim, who's here?
16:25:24 [Zakim]
On the phone I see Tayeb, AndyS, RobS, KendallC, EricP, [ASemantics], DanC, DanielK, DaveB, Patrick, Pat_Hayes, JosD
16:25:26 [Zakim]
[ASemantics] has DirkG
16:25:27 [Zakim]
On IRC I see JosD, alberto, DaveB, dirkx, RRSAgent, Zakim, DanC, KendallC, AndyS, eikeon, rob, ericP
16:25:48 [patH]
patH has joined #dawg
16:25:52 [KendallC]
danc straw polls: do you prefer more free-form discussion or a discussion based on an outline or document.
16:26:36 [KendallC]
(ouch, i may have identified some jos contributions as alberto. mea culpa!)
16:28:28 [DaveB]
16:29:00 [KendallC]
it led to rob s suggesting we remove protocol from the charter. -wink-
16:29:12 [AndyS]
I haven't seen one that does not assume a common protocol if not local access
16:29:20 [KendallC]
(well, sorta suggesting it anyway...)
16:29:27 [alberto]
new uses cases will fit into the overview document - UC discussion should not stop at the moment - there is still a lot to discuss
16:29:31 [KendallC]
rob: :>
16:29:58 [KendallC]
mine didn't assume local access, but i'm not sure i know what you mean
16:30:44 [rob]
That introduction is already loading against self-contained RDF repositories...
16:31:35 [DaveB]
names please, speaker
16:31:44 [KendallC]
that's rob shearer
16:32:55 [rob]
Good point: we're querying RDF models; who parses is beyond our scope.
16:33:37 [KendallC]
danc's straw outline: a generic intro to the problem space (?); a list of use cases: email address, parts catalog, rss feeds; distilled technical requirements; relations to "related techs"
16:34:54 [Zakim]
-[ASemantics]
16:35:13 [ericP]
i'm amused by the idea of it being a draft position
16:35:19 [KendallC]
danc: if yr interested in being an editor, write up a page-long outline of a first document and send to danc.
16:35:30 [Zakim]
+??P15
16:35:41 [KendallC]
dajobe: asks for more use cases
16:36:05 [DaveB]
16:36:24 [KendallC]
kendallc: i asked for more protocol-oriented use cases
16:36:38 [rob]
Specific use cases are easier to shoot down!
16:36:48 [KendallC]
heh
16:37:01 [KendallC]
rob: you *are* a trouble maker ;>
16:37:22 [DaveB]
I'm expecting uses cases to be discarded; it's good when we find them out of scope, not for this round of stuff.
16:37:23 [KendallC]
andys: would like to increase our general pool of UCs before *too much* sorting of them (err. I think?)
16:38:03 [KendallC]
the proposed document may do some of the work of sifting UCs
16:38:45 [rob]
I worry that we might "ignore" boring but relevent use cases.
16:38:50 [KendallC]
rob: yes
16:39:00 [KendallC]
editors shall have to guard against that
16:39:09 [KendallC]
(well IMO)
16:39:46 [KendallC]
alberto: would like the document to have a kind of use case "taxonomy" so that new UCs can be slotted into the right places.
16:40:10 [KendallC]
err, "taxonomy" too heavyweight. alberto wants a list of UC types, it seems.
16:40:33 [KendallC]
a lightweight categorization of UCs
16:41:13 [KendallC]
sorry, "taxonomy" my mishearing of alberto.
16:41:31 [rob]
I think we'll need 20-30 use cases in order to boil commonalities down to 5-7; let's not get complacent and focus too much on any one.
16:42:15 [AndyS]
Is this a good example of a UC section?
16:42:21 [DanC]
yes, starting with 20 to 30 and boiling to 5 to 20 is what I have in mind
16:42:40 [KendallC]
depends on what "boiling down" means
16:42:45 [rob]
It would be nice to get an idea of the full space, and then formally map the group to the 5-7 which represent them.
16:42:51 [DaveB]
(talking over each other on phone)
16:42:54 [rob]
(so that we know we haven't ignored the others)
16:43:27 [alberto]
requirements sound better - taxonomy is odd - I did not meant that - just some "organisation" of UCs
16:43:29 [KendallC]
andys: any inputs to the f2f
16:44:03 [KendallC]
danc: put f2f inputs on next week's agenda, danc will send mail
16:44:06 [DanC]
ACTION DanC: send mail to start discussion of ftf agenda
16:44:24 [Zakim]
-KendallC
16:44:25 [alberto]
waves
16:44:25 [Zakim]
-DanC
16:44:26 [Zakim]
-Patrick
16:44:27 [Zakim]
-RobS
16:44:28 [Zakim]
-DaveB
16:44:29 [Zakim]
-JosD
16:44:29 [Zakim]
-Pat_Hayes
16:44:30 [Zakim]
-Tayeb
16:44:31 [Zakim]
-DanielK
16:44:33 [Zakim]
-??P15
16:44:35 [Zakim]
-AndyS
16:44:37 [Zakim]
SW_DAWG()10:30AM has ended
16:44:39 [Zakim]
Attendees were Tayeb, +1.760.476.aaaa, +1.317.151.aabb, EricP, KendallC, DirkG, DanC, DanielK, Patrick, DaveB, AndyS, RobS, Pat_Hayes, JosD
16:44:42 [DanC]
ok, kendall, so you'll send proposed minutes in email?
16:44:48 [DanC]
RRSAgent, make logs world-readable
16:44:52 [DanC]
RRSAgent, make logs world-access
16:45:09 [KendallC]
danc: i shall do if you'll tell me where to find them on the web :>
16:45:15 [DanC]
RRSAgent, pointer?
16:45:15 [RRSAgent]
See
16:45:20 [KendallC]
thx
16:46:42 [alberto]
alberto has left #dawg
16:47:13 [AndyS]
AndyS has left #dawg
19:04:33 [Zakim]
Zakim has left #dawg
19:06:07 [DanC]
RRSAgent, bye
19:06:07 [RRSAgent]
I see 3 open action items:
19:06:07 [RRSAgent]
ACTION: ericP to set up meeting registration [1]
19:06:07 [RRSAgent]
recorded in
19:06:08 [RRSAgent]
ACTION: item to patricks to write up his car-parts story [2]
19:06:08 [RRSAgent]
recorded in
19:06:08 [RRSAgent]
ACTION: DanC to send mail to start discussion of ftf agenda [3]
19:06:08 [RRSAgent]
recorded in | http://www.w3.org/2004/03/25-dawg-irc | CC-MAIN-2016-30 | refinedweb | 2,748 | 64.44 |
Adding i18n/l10n to Trac plugins (Trac ≥ 0.12)
- Intro and Motivation
- Required workflow
- Enable Babel support for your plugin
- Make the Python code translation-aware
- Make the Genshi templates translation-aware
- Make the Javascript code translation-aware
- Announce new plugin version
- Summing it up
- Do translators work
- Advanced stuff
- Related resources
Intro and Motivation
If you want to learn about translation for a plugin, that as you know already provides one/several message catalog/s, the section 'Do translators work' and following parts are for you.
Ultimately, all plugin maintainers and developers in general, who are facing requests and are willing to take care for growing demand of their plugin to speak same (foreign) language(s) as Trac ≥ 0.12 should, just read on.
i18n, l10n introduction
i18n stands for
i
nternationalizatio
n (count 18 chars between i and n) and is defined as software design for programs with translation support.
l
ocalisatio
n that is abbreviated as l10n could be seen as a follow-up process providing data for one or more locales. It is taking care of feature differences between the original/default (that is English in most cases including Trac) and a given locale as well. Such features are eg sentence structure, including punctuation and formatting of numbers, date/time strings and currencies. Once you did some ground work at the source (i18n), what's remaining is proper translation work (l10n), preserving the meaning of the original while looking as native locale as possible.1
NLS (National Language Support or Native Language Support) is meant to be the sum of both.1, 2
Background and concept of i18n/l10n support for Trac plugins
It begun with adding Babel to Trac, a powerful translation framework. For one part, it is a message extraction tool: it can extract messages from source code files (in our case, Python and Javascript) as well as from Genshi templates, and create catalog templates (
.pot files). It can also create and update the message catalogs (
.po files), and compile those catalogs (
.mo files). For the other part, as a Python library used within Trac, it provides the implementation of the message retrieval functions (
gettext and related). For more information, see Babel.
Some plugin maintainers created their own translation module inside each plugin separately. Growing amount of code redundancy and possibility of error within imperfect copies and variants of a translation module was not a desirable situation. And Trac core maintainers took responsibility with adding functions dedicated to i18n/l10n support for Trac plugins.
The evolution of this functions has been documented in ticket 7497. The final implementation as mentioned there in comment 12 was introduced to Trac trunk in changeset r7705 and finally done with changeset r7714.
Now adding the needed i18n/l10n helper functions is done by importing a set of functions from
trac/util/translation.py and providing the necessary extra information (domain) for storing and fetching the messages from the plugin code into plugin specific message catalogs. During plugin initialization, the dedicated translation domain is created as well and corresponding catalog files holding translated messages are loaded in memory. If everything is setup correctly, when a translatable text is encountered at runtime inside the plugin's code, the i18n/l10n helper functions will try to get the corresponding translation from a message catalog of the plugin's domain.
The message catalog selection is done according to the locale setting. Valid settings are a combination of language and country code, optionally extended further by the character encoding used, i.e. to read like ‘de_DE.UTF-8’. Trac uses UTF-8 encoding internally, so there is not much to tell about that. 'C' is a special locale code since it disables all translations and programs use English texts as required by POSIX standard.3
Required workflow
You need to:
- specify in your plugin's
setup.pyfile on which files the Babel commands will have to operate
- create a
setup.cfgfiles for adding options to the Babel commands
- in your Python source code:
- define specializations of the translation functions for your specific domain; there's a helper function for doing that easily
- in the "root"
Componentin your plugin (one you're sure is always enabled) and initialize the translation domain in its
__init__method
- use your translation functions appropriately
- in your Genshi templates:
- be sure to have the necessary namespace declaration and domain directive in place
- use the i18n: directive as appropriate
- in your Javascript code:
- be sure to load your catalog and define your domain specific translation functions
- use the translation functions as appropriate
Enable Babel support for your plugin
Add Babel commands to the setup (
setup.py)
Babel by default only extracts from Python scripts. To extract messages from Genshi templates also, you'll have to declare the needed extractors in
setup.py:
Preset configuration for Babel commands (
setup.cfg)
Add some lines to
setup.cfg or, if it doesn't exist by now, create it with the following content:
[extract_messages] add_comments = TRANSLATOR: msgid_bugs_address = output_file = <path>/locale/messages.pot # Note: specify as 'keywords' the functions for which the messages # should be extracted. This should match the list of functions # that you've listed in the `domain_functions()` call above. keywords = _ N_ tag_ # Other example: #keywords = _ ngettext:1,2 N_ tag_ width = 72 [init_catalog] input_file = <path>/locale/messages.pot output_dir = <path>/locale domain = foo [compile_catalog] directory = <path>/locale domain = foo [update_catalog] input_file = <path>/locale/messages.pot output_dir = <path>/locale domain = foo
Replace
<path> as appropriate (i.e. the relative path to the folder containing the
locale directory, for example
mytracplugin).
This will tell Babel where to look for and store message catalog files.
In the
extract_messages section there is just one more lines you may like to change:
msgid_bugs_address. To allow for direct feedback regarding your i18n work, add a valid e-mail address or a mailing list dedicated to translation issues there.
The
add_comments line simply lists the tags in the comments surrounding the calls to the translation functions in the source code that have to be propagated to the catalogs, see extract_messages in Babel's documentation. So you will want to leave that one untouched.
Register message catalog files for packaging
To include the translated messages into the packaged plugin you need to add the path to the catalog files to
package_data in the call for function
setup() in
setup.py:
Make the Python code translation-aware
Prepare domain-specific translation helper functions
Pick a unique name for the domain, as this will be the basename for the various translation catalog files, eg
foo/locale/fr/LC_MESSAGES/foo.po for the French catalog.
At run-time, the translation functions (typically
_(...)) have to know in which catalog the translation will be found. Specifying the 'foo' domain in every such call would be tedious, that's why there's a facility for creating partially instantiated domain-aware translation functions:
domain_functions.
This sample helper function should be called at module load time:
from trac.util.translation import domain_functions _, tag_, N_, add_domain = \ domain_functions('foo', ('_', 'tag_', 'N_', 'add_domain'))
The translation functions which can be bound to a domain are:
'_': extract and translate
'ngettext': extract and translate (singular, plural, num)
'tgettext',
'tag_': same as
'_'but for Markup
'tngettext',
'tagn_': same as
'ngettext'but for Markup
'gettext': translate only, don't extract
'N_': extract only, don't translate
'add_domain': register the catalog file for the bound domain
Note:
N_ and
gettext() are usually used in tandem. For example, when you have a global dict containing strings that need to extracted, you want to mark those strings for extraction but you don't want to put their translation in the dict: use
N_("the string"); when you later use that dict and want to retrieve the translation for the string corresponding to some key, you don't want to mark anything here: use
gettext(mydict.get(key)).
To inform Trac about where the plugin's message catalogs can be found, you'll have to call the
add_domain function obtained via
domain_functions as shown above. One place to do this is in the
__init__ function of your plugin's main component, like this:
def __init__(self): import pkg_resources # here or with the other imports # bind the 'foo' catalog to the specified locale directory try: locale_dir = pkg_resources.resource_filename(__name__, 'locale') except KeyError: pass # no locale directory in plugin if Babel is not installed else: add_domain(self.env.path, locale_dir)
assuming that folder
locale will reside in the same folder as the file containing the code above, referred to as
<path> below (as can be observed inside the Python egg after packaging).
The i18n/l10n helper functions are available inside the plugin now, but if the plugin code contains several python script files and you encounter text for translation in one of them too, you need to import the functions from the main script, say its name is
api.py, there:
from api import _, tag_, N_
Mark text for extraction
In python scripts you'll have to wrap text with the translation function
_() to get it handled by translation helper programs.
Note, that quoting of (i18n) message texts should be done in double quotes. Single quotes are reserved for string constants (see commit note for r9751).
If you fail to find all desired texts, you will notice this by seeing those messages missing from the message catalog. If the plugin maintainer is unaware of your i18n work or unwilling to support it and he adds more messages without the translation function call, you have to do the wrapping of these new texts too.
Make the Genshi templates translation-aware
See the Genshi documentation on this topic, Internationalization and Localization.
Text extraction from Python code and Genshi templates
Message extraction for Genshi templates should be done automatically. However there is the markup
i18n:msg available to ensure extraction even from less common tags. For a real-world example have a look at Trac SVN changeset r9542 for marking previously undetected text in templates.
Runtime support
Extraction is automatic, however message retrieval at runtime is not. You have to make sure you've specified the appropriate domain in your template, by adding a
i18n:domain directive. Usually you would put it in the top-level element, next to the mandatory
xmlns:i18n namespace declaration.
For example:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" ""> <html xmlns="" xmlns: ... </html>
Make the Javascript code translation-aware
Text extraction from Javascript code
Adding support for translating the marked strings in the Javascript code is a bit more involved.
We currently support only statically deployed Javascript files, which means they can't be translated like template files on the server, but that the translation has to happen dynamically on the client side. To this end, we want to send an additional
.js file containing a dictionary of the messages that have to be translated, and only those. In order to clearly identify which strings have to be present in this dictionary, we'll extract the messages marked for translation (the usual
_(...) ways) from the Javascript code into a dedicated catalog template, and from there, we'll create dedicated catalogs for each locale. In the end, the translations present in each compiled catalog will be extracted and placed into a
.js file containing the messages dictionary and some setup code.
The first change is to use
get_l10n_js_cmdclass in lieu of
get_l10n_cmdclass. The former adds a few more setup commands for extracting messages strings from Javascript
.js files and
<script type="text/javascript"> snippets in
.html files, initialization and updating of dedicated catalog files, and finally compiling that catalog and creating a
.js file containing the dictionary of strings, ready to be used by the
babel.js support code already present in Trac pages.
The change to
setup.py looks like this:
Now, as you need to actually send that
.js file containing the messages dictionary, call
add_script() as appropriate in the
process_request() method from your module:
Now you need to expand the
setup.cfg file with the configuration that the new
cmdclass dedicated to Javascript translation need. Those classes all end with an
_js suffix.
[extract_messages_js] add_comments = TRANSLATOR: copyright_holder = <Your Name> msgid_bugs_address = <Your E-Mail> output_file = <path>/locale/messages-js.pot keywords = _ ngettext:1,2 N_ mapping_file = messages-js.cfg [init_catalog_js] domain = foo-js input_file = <path>/locale/messages-js.pot output_dir = <path>/locale [compile_catalog_js] domain = foo-js directory = <path>/locale [update_catalog_js] domain = foo-js input_file = <path>/locale/messages-js.pot output_dir = <path>/locale [generate_messages_js] domain = foo-js input_dir = <path>/locale output_dir = <path>/htdocs/foo
As before, replace
<path> with what's appropriate for your plugin. Note that the domain name is now
foo-js, not just
foo as before. This is necessary as we want to have only the strings actually needed Javascript to be stored in the
.js file containing the messages dictionary.
We need to configure separately how to do the extraction for this
messages-js.pot catalog template.
The
messages-js.cfg file has the following content:
# mapping file for extracting messages from javascript files into # <path>/locale/messages-js.pot (see setup.cfg) [javascript: **.js] [extractors] javascript_script = trac.util.dist:extract_javascript_script [javascript_script: **.html]
This procedure needs to be simplified.
Announce new plugin version
The plugin will not work with any Trac version before 0.12, since import of the translation helper functions introduced for 0.12 will fail. It is possible to wrap the import with a '
try:' and define dummy functions in a corresponding '
except ImportError:' to allow the plugin to work with older versions of Trac, but there might already be a different version for 0.11 and 0.12, so this is not required in most cases. If it is strictly required for your plugin, have a look at
setup.py of the Mercurial plugin provided with Trac.
In all other cases you'll just add a line like the following as another argument to the setup() function in plugin's
setup.py:
install_requires = ['Trac >= 0.12'],
To help with identification of the new revision and make your work visible to other users, you should bump the plugin's version number. This is done by changing the version/revision, typically in
setup.cfg or
setup.py. And you may wish to leave a note regarding your i18n work along the copyright notices as well.
Summing it up
Here's an example of the changes required to add i18n support to the HudsonTrac plugin (
trac-0.12 branch):
- Initial Python translation support
- Template translation support (get_l10n_cmdclass)
- Javascript translation support (get_l10n_js_cmdclass)
You'll find another example attached to this page. That is Sub-Tickets plugin v0.1.0 and a diff containing all i18n/l10n related work to produce a German translation based on that source.
Do translators work
General advice from TracL10N on making good translation for Trac applies here too.
I.e. it's desirable to maintain a consistent wording across Trac and Trac plugins. Since this is going beyond the scope of aforementioned TracL10N, there might be the need for more coordination. Consider joining the Trac plugin l10n project, that utilizes Transifex for uniform access to message catalogs for multiple plugins backed by a dedicated (Mercurial) message catalog repository at Bitbucket.org. Trac has some language teams at Transifex as well, so this is a good chance for tight translator cooperation.
Switch to root directory of plugin's source at the command line:
cd /usr/src/trac_plugins/foo
Extract the messages that where marked for translation before, or on case of Genshi templates are exposed by other means:
python ./setup.py extract_messages
The attentive reader will notice that the argument to
setup.py has the same wording as a section in
setup.cfg, that is not incidental. And this does apply to the following command lines as well.
If you attempt to improve on existing message catalogs, you'll update the one for your desired language:
python ./setup.py update_catalog -l de_DE
If you omit the language selection argument
-l and identifier string, existing catalogs of all languages will be updated, and within seconds on stock hardware.
But if you happen to do all the i18n work before, then you know you there's nothing to update right now. In that case create the message catalog for your desired language:
python ./setup.py init_catalog -l de_DE
The language selection argument
-l and identifier string are mandatory here.
Now fire up the editor of your choice. There are dedicated message catalog (.po) file editors that ensure for quick results as a beginner as well as make working on large message catalogs with few untranslated texts or translations marked 'fuzzy' much more convenient. See dedicated resources for details on choosing an editor program as well as for help on editing .po files.4, 5
If not already taken care for by your (PO) editor, the place to announce yourself as the last translator is after the default
TRANSLATOR: label at top of the message catalog file.
Compile and use it
Compile the
messages.po catalog file with your translations into a machine readable
messages.mo file:
python ./setup.py compile_catalog -f -l de_DE
The argument
-f is needed to include even the msgid's marked 'fuzzy'. If you have prepared only one translated catalog the final language selection argument
-l and identifier string are superfluous. But as soon as there are several other translations that you don't care, it will help to select just your work for compilation.
Now you've used all four configuration sections in
setup.cfg, that are dedicated to i18n/l10n helper programs. You could finish your work by packaging the plugin.
Make the python egg as usual:
python ./setup.py bdist_egg
Install the new egg and restart your web-server after you made sure to purge any former version of that plugin (without your latest work).
Note that if the plugin's
setup.py has installed the proper extra commands (
extra['cmdclass'] = cmdclass like in the above), then
bdist_egg will automatically take care of the
compile_catalog command, as well as the commands related to Javascript i18n if needed.
Advanced stuff
Translating
Option* documentation
Trac 1.0 added support for a special kind of
N_ marker,
cleandoc_, which can be used to reformat multiline messages in a compact form. There's also support to apply this "cleandoc" transformation to the documentation of instances of
trac.config.Option and its subclasses. However, this support is coming from a special Python extractor which has to be used instead of the default Python extractor from Babel.
The additional change is:
The default
cleanup_keywords (the
Option subclasses) are not automatically
keywords however. The corresponding option for the
[extract_messages] section of the
setup.cfg file should therefore contain the
cleandoc_ token, or the
Config subclasses together with the position of the doc argument in that subclass.
As an example, see the following excerpt from the SpamFilter plugin setup.cfg file:
[extract_messages] add_comments = TRANSLATOR: msgid_bugs_address = [...] output_file = tracspamfilter/locale/messages.pot keywords = _ ngettext:1,2 N_ tag_ Option:4 BoolOption:4 IntOption:4 ListOption:6 ExtensionOption:5 width = 72
This makes it possible for the extractor to get the doc strings from those options automatically. For example, in adapters.py:
class AttachmentFilterAdapter(Component): """Interface to check attachment uploads for spam. """ implements(IAttachmentManipulator) sample_size = IntOption('spam-filter', 'attachment_sample_size', 16384, """The number of bytes from an attachment to pass through the spam filters.""", doc_domain='tracspamfilter')
as you can see, it's also necessary to specify the domain, otherwise the lookup of the translated message at runtime (within the [[TracIni]] macro, typically) will fail.
About 'true' l10n
A human translator will/should do better than an automatic translation, since good l10n has more of a transcription than pure translation word by word. It's encouraging to see the raise of native words for such terms like changeset, ticket and repository in different languages. This will help Trac to not only fulfil its promise to help project teams focusing on their work, but even extend its use to project management in general, where use of native language is much more common or even required in contrast to the traditional software development.
Related resources
See TracL10N and more specifically TracL10N#ForDevelopers, which contains general tips that are also valid for plugin translation.
1 - Internationalization and localization
2§ion=18 - Multilingualism in computing
3 - GNU 'gettext' utilities: Locale Names
4 - GNU 'gettext' utilities: Editing PO Files
5 - PO Odyssey in 'Localization/Concepts' section of KDE TechBase
Attachments (2)
- itota-trac-subtickets-plugin-cb202be.tar.gz (5.5 KB ) - added by 7 years ago.
local copy of TracSubtickets plugin source as reference for example
- trac-subtickets-plugin_i18n-l10n.patch (11.8 KB ) - added by 7 years ago.
i18n/l10n patch for TracSubtickets plugin maintained by Takashi Ito
Download all attachments as: .zip | https://trac.edgewall.org/wiki/CookBook/PluginL10N | CC-MAIN-2017-22 | refinedweb | 3,473 | 53.81 |
Python Glossary
This page is meant to be a quick reference guide to Python. It is far from done, but it is a start. If you see something that needs to be added, please let me know and I will add it to the list.
">>>" The default Python prompt of the interactive shell. Often seen for code examples which can be executed interactively in the interpreter.
abs Return the absolute value of a number.
argument Extra information which the computer uses to perform commands.
argparse Argparse is a parser for command-line options, arguments and subcommands.
assert Used during debugging to check for conditions that ought to apply
assignment Giving a value to a variable.
block Section of code which is grouped together
break Used to exit a for loop or a while loop.
class A template for creating user-defined objects.
compiler Translates a program written in a high-level language into a low-level language.
continue Used to skip the current block, and return to the "for" or "while" statement
conditional statement Statement that contains an "if" or "if/else".
debugging The process of finding and removing programming errors.
def Defines a function or method
dictionary A mutable associative array (or dictionary) of key and value pairs. Can contain mixed types (keys and values). Keys must be a hashable type.
distutils Package included in the Python Standard Library for installing, building and distributing Python code.
docstring A docstring is a string literal that occurs as the first statement in a module, function, class, or method definition.
__future__ A pseudo-module which programmers can use to enable new language features which are not compatible with the current interpreter.
easy_install Easy Install is a python module (easy_install) bundled with setuptools that lets you automatically download, build, install, and manage Python packages.
evaluation order Python evaluates expressions from left to right. Notice that while evaluating an assignment, the right-hand side is evaluated before the left-hand side.
exceptions Means of breaking out of the normal flow of control of a code block in order to handle errors or other exceptional conditions
expression Python code that produces a value.
filter filter(function, sequence) returns a sequence consisting of those items from the sequence for which function(item) is true
float An immutable floating point number.
for Iterates over an iterable object, capturing each element to a local variable for use by the attached block
function A parameterized sequence of statements.
function call An invocation of the function with arguments.
garbage collection The process of freeing memory when it is not used anymore.
generators A function which returns an iterator.
high level language Designed to be easy for humans to read and write.
IDLE Integrated development environment
if statement Conditionally executes a block of code, along with else and elif (a contraction of else-if).
immutable Cannot be changed after its created.
import Used to import modules whose functions or variables can be used in the current program.
indentation Python uses white-space indentation, rather than curly braces or keywords, to delimit blocks.
int An immutable integer of unlimited magnitude.
interactive mode When commands are read from a tty, the interpreter is said to be in interactive mode.
interpret Execute a program by translating it one line at a time.
IPython Interactive shell for interactive computing.
iterable An object capable of returning its members one at a time.
lambda They are a shorthand to create anonymous functions.
list Mutable list, can contain mixed types.
list comprehension A compact way to process all or part of the elements in a sequence and return a list with the results.
literals Literals are notations for constant values of some built-in types.
map map(function, iterable, ...) Apply function to every item of iterable and return a list of the results.
methods A method is like a function, but it runs "on" an object.
module The basic unit of code reusability in Python. A block of code imported by some other code.
object Any data with state (attributes or value) and defined behavior (methods).
object-oriented allows users to manipulate data structures called objects in order to build and execute programs.
pass Needed to create an empty code block
PEP 8 A set of recommendations how to write Python code.
Python Package Index Official repository of third-party software for Python
Pythonic An idea or piece of code which closely follows the most common idioms of the Python language, rather than implementing code using concepts common to other languages.
reduce reduce(function, sequence) returns a single value constructed by calling the (binary) function on the first two items of the sequence, then on the result and the next item, and so on.
set Unordered set, contains no duplicates
setuptools Collection of enhancements to the Python distutils that allow you to more easily build and distribute Python packages
slice Sub parts of sequences
str A character string: an immutable sequence of Unicode codepoints.
strings Can include numbers, letters, and various symbols and be enclosed by either double or single quotes, although single quotes are more commonly used.
statement A statement is part of a suite (a "block" of code).
try Allows exceptions raised in its attached code block to be caught and handled by except clauses.
tuple Immutable, can contain mixed types.
variables Placeholder for texts and numbers. The equal sign (=) is used to assign values to variables.
while Executes a block of code as long as its condition is true.
with Encloses a code block within a context manager.
yield Returns a value from a generator function.
Zen of Python When you type "import this", Python’s philosophy is printed: | https://www.pythonforbeginners.com/cheatsheet/python-glossary | CC-MAIN-2020-16 | refinedweb | 944 | 56.76 |
This article describes how to extract icons from an executable module (EXE or DLL), and also how to get the icons associated with a file.
In this article, you will find how to get the icon image that best fits the size you want to display. You can also find how to split an icon file to get its image.
Icons are a varied lot—they come in many sizes and color depths. A single icon resource—an ICO file, or an icon resource in an EXE or DLL file—can contain multiple icon images, each with a different size and/or color depth.
Windows extracts the appropriate size/color depth image from the resource depending on the context of the icon's use. Windows also provides a collection of APIs for accessing and displaying icons and icon images.
The code I introduce will help you extract icons from executable modules (EXE, DLL) without the need to know the Windows APIs that are used in this situation.
The code will also help you in extracting specific icon images from an icon file, and will help you in extracting the icon image that best fits a supplied icon size.
If you want to understand what is going on in this code, you should know how to call APIs from C# code. You also need to know the icon format, about which you will find here: MSDN.
First, you need to add a reference to TAFactory.IconPack.dll, or add the project named IconPack to your project.
Add the following statement to your code:
using TAFactory.IconPack;
Use the IconHelper class to obtain the icons as follows:
IconHelper
//Get the open folder icon from shell32.dll.
Icon openFolderIcon = IconHelper.ExtractIcon(@"%SystemRoot%\system32\shell32.dll", 4);
//Get all icons contained in shell32.dll.
List<icon> shellIcons = IconHelper.ExtractAllIcons(@"%SystemRoot%\system32\shell32.dll");
//Split the openFolderIcon into its icon images.
List<icon> openFolderSet = IconHelper.SplitGroupIcon(openFolderIcon);
//Get the small open folder icon.
Icon smallFolder = IconHelper.GetBestFitIcon(openFolderIcon,
SystemInformation.SmallIconSize);
//Get large icon of c drive.
Icon largeCDriveIcon = IconHelper.GetAssociatedLargeIcon(@"C:\");
//Get small icon of c drive.
Icon smallCDriveIcon = IconHelper.GetAssociatedSmallIcon(@"C:\");
//Merge icon images in a single icon.
Icon cDriveIcon = IconHelper.Merge(smallCDriveIcon, largeCDriveIcon);
//Save the icon to a file.
FileStream fs = File.Create(@"c:\CDrive.ico");
cDriveIcon.Save(fs);
fs. | https://www.codeproject.com/articles/32617/extracting-icons-from-exe-dll-and-icon-manipulatio?fid=1533821&df=90&mpp=10&sort=position&spc=none&select=4389947&tid=3715675 | CC-MAIN-2016-50 | refinedweb | 387 | 59.7 |
Le dim 25/08/2002 à 06:19, Niklas =?iso-8859-1?q?H=F6glund=22?= @club-internet.fr a écrit : > On Thu, 22 Aug 2002 12:20:38 +0000, Tom Hart wrote: > > On my university's network, for example, students can't even change > > their backgrounds (except by using "set as wallpaper" from within a web > > browser). I doubt most sysadmins would want to give users the freedom to > > add system groups. > > On mine, we can. We're using the AFS filesystem, and any user can create > groups prefixed by his username. I (su99-nho) have a group called > su99-nho:proj. > > I think this is a good way to do it. Only administrators can create any > groups, but all users have subnamespaces, that are still part of the > global namespace. Can you grant rights on your group, eg allow all users in one of your groups to modify another group? For example, if the sysadmin creates a "club" user, with a "club" group, will it be possible to permit members of that group to decide to add/remove someone from the group, so that a students' club can manage itself without refering to the sysadmin again after the creation? Snark on #hurd, #hurdfr | https://lists.debian.org/debian-hurd/2002/08/msg00254.html | CC-MAIN-2017-22 | refinedweb | 205 | 71.34 |
Hello everyone, I am java noob so please bear with me, I have two classes for a program thats supposed to search for books but I am currently stuck!. Where I am stuck is at the bottom of the BookSearch class, and I am trying to essentially only search my array for the price and title, but, in my book class I declared the attributes of the book to have 3 parameters (see below). So the little tiny thing that I can't figure out is that if I want to compare 2 values given to me by the user (a title and a price) then I only want to compare those 2 parameters, but I have no idea how to go about it since my Book class has 3 parameters, so essentially I am asking how do I check through an array with 3 parameters but only want to check 2 of them for the entire array. I tried if bkArr[i].equals(pric) && bkArr[i].equals(titl) ... but it didn't work and I know it wouldn't work, it just dosen't look good. I am completely baffled by this and have spent 3 hours just staring at my screen trying to figure something which I think should be very easy to do. If anyone dosen't understand what I am trying to do please ask and Il try to explain again, thanks in advance !
class Book { //Attributes of Book private String title; private long ISBN; private double price; //Constructor of Book public Book() { System.out.println("Creating Book....."); title = "abc"; price = 25; ISBN = 1234; } public Book(String ti, long ib, double pr) { title = ti; price = pr; ISBN = ib; } //Methods of book public Book(Book bk) { //Copy Constructor System.out.println("Creating object with copy constructor....."); title = bk.title; price = bk.price; ISBN = bk.ISBN; } public void setPrice(double pr) {//sets the price of the book price = pr; } public double getPrice() {//gets the price of the book return price; } public void setTitle(String ti) {//sets the title of the book title = ti; } public String getTitle() {//gets the title of the book return title; } public void setISBN(long num) {//sets the ISBN of the book ISBN = num; } public long getISBN() {//gets the ISBN of the book return ISBN; } public String toString() {//returns book values System.out.println("The book title is " + title + ", the ISBN number is " + ISBN + " and the price is " + price +"$.\n\n"); return (title + " " + ISBN + " " + price); } }
import java.util.Scanner; public class BookSearch { public static void main (String[] args) { String titl, yn; int i, pric; //Create 10 books with the array Book[] bkArr = new Book[10]; //Create 10 book objects with values Book b1 = new Book ("hi",10, 1001); Book b2 = new Book ("hi",45, 1002); Book b3 = new Book ("hi",50, 1003); Book b4 = new Book ("hi",100, 1004); Book b5 = new Book ("hi",75, 1005); Book b6 = new Book ("hi",65, 1006); Book b7 = new Book ("hi",40, 1007); Book b8 = new Book ("hi",10, 1008); Book b9 = new Book ("hi",10, 1009); Book b10 = new Book ("hi",100,1010); bkArr[0] = b1; bkArr[1] = b2; bkArr[2] = b3; bkArr[3] = b4; bkArr[4] = b5; bkArr[5] = b6; bkArr[6] = b7; bkArr[7] = b8; bkArr[8] = b9; bkArr[9] = b10; Scanner kb = new Scanner(System.in); System.out.println("Please enter a book title, a price and either 'Yes' or 'No' for a combined search"); titl = kb.next(); pric = kb.nextInt(); yn = kb.next(); if (yn.equals("yes")) { for (i = 0; i < bkArr.length; i++) { if (bkArr[i]. } } if (yn.equals("No")) { } } } | http://www.javaprogrammingforums.com/object-oriented-programming/36848-how-search-through-values-array.html | CC-MAIN-2015-27 | refinedweb | 598 | 63.93 |
1. I'm here with Mr. Billy Hollis. If you can introduce yourself to the folks and give us a little insight into who you are and what you do.
As you can tell from the grey hair I go back a long way in the business and I learned BASIC in 1975, learned FORTRAN in 1973 and started professional software development in 1978 on a system called the Micro-data Reality System in language called reality basic, a predecessor of the PIC operating system. The PIC System was interesting in that it had a database that had an interesting delimited format and the database was actually exposed at the operating system level which simplified a lot of programming. It had quite a lot of pretty advanced concepts that were not worked into other system for 10 to 15 years later. So I've learned a lot of languages and written a lot of software over the years. In the .NET world I was co-author with Rocky Lhotka of the first book on Visual Basic .NET which was the only book available on Visual Basic .NET for about six months and as a consequence of that I was able to get involved in a lot of the early efforts such as the .NET developer tour, instructed people at Microsoft on .NET technologies for quite a while. In the last few years I've been running a consulting practice based on .NET, with my partner, and we do medium to large projects that require more advanced application of the leading edge concepts in .NET. So for example in 2002 we were doing the advanced smart client stuff that other people really hadn't realized was an important part of the .NET world. So I specialized a bit in smart client, user interface stuff and recently I've been doing a fair amount of work on workflow. The nice thing about that, and I worked on fourth generation languages in the early 90s too, so you get exposed to concepts that other people don't see as early, and that way when those concepts hit the mainstream platforms such as Microsoft, you have a better understanding of what they are good for. So for example the LINQ query stuff that we are doing now is not dissimilar in spirit to a lot of the query stuff available in the 4GLs that came out in the late 80s and early 90s. Having worked for a company that sold one of those I have a pretty good feeling about LINQ because it's giving me back some things that I haven't had for a lot of years.
2. Yes John Lam made the point in his Keynote about dynamic languages and the fact they've been around for over 40 years, is the time right for a change?
n the entire time that I've been doing languages I think that the only dramatically new concepts I've seen were: moving to relational databases from the flat index structures that we looked at, at the time; moving from procedural based to object based design and development and moving from character based to GUI user interfaces and the event driven paradigm that came out of that. Everything else is almost just syntactic sugar or other kinds of frills around those 3 big transitions, and all of them took a long time. All of them took at least ten years for people to grasp what they were all about and why they were important and how to do them and every single one of them resulted in a dramatically new tool or product that became a mainstream product, because when you take dramatic things like that you can't really put them on existing products. There's a limit to what you can bolt on the stuff you've got now, before you get to the point where you have to rethink things. So John Lam in his Keynote is talking about Ruby and some of the concepts there and he was getting at the point that we are now reaching that point in the asynchronous world, the world of the web, the world of all the threading things that we can do now, multiprocessor machines, that our platforms demand a new move of that nature. We don't really know exactly what it is going to look like yet, but I think we are on the verge of another transition that's of the same magnitude as the others.
3. Interesting. So along that point, I think you and others believe change is coming, especially in terms of enterprise development, with technologies like Windows Presentation Foundation?
I tend not to use the word enterprise because there is a certain amount of over-emphasis on that from my perspective. And that comes out of the competitive nature of the industry. Java made their biggest impact in the enterprise space, so Microsoft responded by attempting to make a similar impact in the enterprise space. And they orient a lot of what they do around that space. That's ok and that space certainly is important, but I'm a little more of an advocate of the long tail theory which you look at ( I will try to do this right from the point of view of the viewers): you would take a graph and there are few companies that do a lot of development and then the curve kind of slopes down in terms of the size of the company and the amount of development they do. There's a gradually decreasing slope there. Companies like Microsoft, Oracle and Sun tend to work on that big part of the graph because in a short span they get a lot of the activity, but you shouldn't underestimate the stuff that's going on and what they call the long tail. Because when start adding all those little smaller companies you end up with a pretty big application space there too. There is a similar concept in what Amazon does, in that the strength of Amazon is not that they sell 2 million of the latest Harry Potter book. I mean they are happy to do that of course, that's in the big part. The strength of Amazon is that they make it practical for you to order from the long tail and that is in fact quite a lot of where their profit and volume come from; it is the fact that it's all of those books that only sell 10 or 15 copies a year and they can still afford to do it; they take advantage of the fact that there is a latent demand for that, for that kind of thing. In the software world I think there is big latent demand that is not being satisfied right now, in the long tail of software development. The tools are very much oriented towards enterprise use and the power that the enterprise folks need sometimes is over-kill for what the folks need down there in that long tail. And our tools haven't caught up with that yet. If we look at the tools we used to have, people deride Access and I wrote an article myself called "Abusing Microsoft Access", about people who abuse it, but it was suitable for a lot of those long tail applications, in a way that we don't have a tool today. And to me the biggest limitation in .NET is that it works well for me and it works well for the people in the long tail, and I tend to go a little further down from that. But it doesn't work well for the people the further down that graph that you go. And the focus of Microsoft has been in the enterprise space so much because they've kind of owned that middle space and I think it has been allowed to languish a bit. I'd like to see more attention given to the needs of developers in that space. If you are a developer in a small company you can't afford to be an architect and up on the latest language innovations, you really got to worry more about the business needs because there's only you and maybe one other person and so you have to be more a generalist which means that the more the details that you can hide, the more the plumbing that you can hide, the better off you are. And I think this is one of the forces driving this need towards the idea of a transition, to get away from some of the plumbing. I talked about this in a one of the blog posts I put up a while back. I discussed what I called the Home Depot effect of using .NET and in the comments people from the Java world chimed in and said they felt the same thing, that when you go into modern frameworks that are targeted at the enterprise and say I want to do some fairly simple action and you're trying to find out inside that framework what to do, the emotional experience is very similar to walking into a Home Depot. If you're trying to find some plumbing part and you don't exactly know what it's called and you don't know where it is and you wander around the aisles looking for it and if you are lucky enough you might find it, but maybe the directions on the package don't really tell you very much about how to use it; they assume that if you are there for that part you already know. The same emotional experience is to a great extent present in the complex frameworks we have today; you walk into the framework and you're just overwhelmed by how much is there and overwhelmed by the effort it takes to locate and learn to use the pieces that you need.
4. Can you comment on the complexity of the Composite Application Block and how long it would take somebody to ramp up to actually use what's in there?
Yes that's a perfect example of what some of the patterns and practices guys are doing and addressing that tall part of the graph and ignoring the long tail. To be fair to them they construe that as their mission because obviously the bigger you are, the more you need patterns, the more you need consistency, the more you need functionality. You look at a block such as the Composite Application Block and the ramp-up time on it is severe. You have a large enough application or you have a long string of applications that need to have a certain level of consistency inside a business, then the Composite Application Block can make a lot of sense because you get to distribute that large ramp-up time, that time it takes to acclimate yourself to it, over a big amount of product. But if you're doing a modest size application you are down there in that long tail and you are working on an application that is 20 forms or something, a line of business app that is going to be used by a hundred users or something like that, the Composite Application Block is never going to be a good fit because you're going to have to learn too much, you're going to have to spend too long figuring out how to apply it to your circumstances. So I think that in some respects the Patterns and Practices blocks while there is a space in which they do very well and you get the advantages of tested, very functional code that does a lot, that they get over-sold a little bit as kind of a universal solution when they really are not. There is a space in which they work well. The Composite Application Block for example. I have been asking members of my audience:"Who uses it?", and if they say that they use it, I ask "How long did it take you to understand it?"; of the ones who successfully implemented it I think the smallest answer that I've gotten so far was a month. And it goes up from there, so you're talking about some severe time and you can only really afford to do that if you are in that tall part of the graph.
5. If you got a year long project. If you got a few months' project you can't spend a month ramping up on a framework.
Exactly.
6. One of the things I've noticed and maybe you have some insight into it, is that there is the Drag and Drop data binding wizard stuff for a quick application, and there is Enterprise Library, is there something in the middle?
That's a good point. The data binding is oriented towards a simple, sort of low-end case but you still have to know some things, and actually because of that lack that there's Enterprise Library with fairly sophisticated things there - you can even use data binding with enterprise library I suppose - but I would say there is more than one gap. There is one gap in the extreme low end in that if I just spray some forms out with the data binding we have now, they'll work until I start trying to do some fairly sophisticated things and then I'm going to have to learn some workarounds for things that the data binding does not do quite as transparently or as automatically as I would like. The number of those things gets less with every generation of data binding, but there're still there. One of the things that is missing is the low-end Microsoft access type thing where you literally don't worry about the data binding at all. When did you worry about data binding doing a Microsoft access application? You never did. We haven't achieved that level of simplicity of data binding in the .NET world.
7. More than a few people have said "We need an Access like development tool environment that puts .NET code out the back end." What do you think?
I think that having an Access type tool that would resolve into .NET code, would make a lot of sense; even if it were only just one way that you were able to produce the code and then work off in that world, that would be better than what a lot of people have to do now, because they just have to learn too much. And then when you step above data binding there is also a space in which I'm not sure there's an optimal solution, but there you see more of a tendency for people to develop their own. So that's the space I'm in. I have my own data-binding implementation. Richard Hale Shaw made a good point this morning in a panel that we did that you have to differentiate data binding as a technology in Windows forms or ASP.NET from data binding as a pattern. The one thing you never want to do is to have any sized application that is more than a dozen forms in which you write a lot of custom logic to begin moving things from controls into containers and back. There's just a recipe for a buggy, unstable application. You don't want to do that, you want to use a data binding pattern somewhere. Does that mean you use the data binding technology that is built in? It might. But in some cases such as my own I actually implemented the data binding pattern with my own components. And thereby I have more control, I get to target that technology more precisely at my needs and still having the benefits of not getting to write all that GUI code that is essentially plumbing and has nothing to do with the business logic of the application.
8. When working with data binding and events, where you can plug into that process to interrupt things to validate, and is that one of the reasons why you came out with your data binding?
That's right. Having started very early in 2002, being one of the first people doing large scale forms developments (formed based development) in .NET, I rapidly realized what the limitations were at that time, which were less than the limitations today and having actually been dissatisfied with VB classic data binding, I had already written a data binding replacement in VB classic; it was much easier to write it in Visual Basic .NET of 2002 because I had full object capabilities to do it with. But yes, I brought that pattern over, implemented it and we've been using that now for four years and every time they improve data binding I go to my partner and say "Well maybe we should switch over to data binding because they've made it better" and he just shakes his head and says "We've got something that works and we control it and it does exactly what we want". If you come to me at a conference and you want to ask some detailed question on data binding I'm not the right person to ask because I've got my own and know enough about the built-in data binding just to judge about what it is able to do and use it in demos.
9. You mention it's a time of rapid change, maybe we can walk through some of the technologies and see how you see them fitting into the future of development.
This is an extraordinary challenging time for people who want to stay out there on the edge and take best advantage of the technologies that are available. That doesn't mean the entire development community by any means, but there's a pretty good size chunk of it that attempts to stay out there (20% or 25%). And for those folks this is probably the most challenging time in our careers. If we look back to the last equivalent period, at least to the Microsoft world (most of my comments are in that context), if we look back to the 2001-2002 time period when we were getting ready for .NET and we were learning all the technologies that were in it, most of us had plenty of time to do that because after the Dot Com meltdown there wasn't that much to do that was any fun anyway; who wanted to do all that ASP nasty stuff anyway? So we had a fair amount of time on our hands that we could invest in learning how to take best advantage of these technologies. During that period I wrote a lot of books and I did a lot of training and spent a lot of time writing sample applications. That ended when production work began in 2002, and since then it has been an unbroken rise in demand for development in the .NET world. There was an article in the Wall Street Journal not long ago that stated .NET developer is one of the top 5 of in demand positions in the whole economy and I don't mean just in the tech industry, but in the entire economy in the States. The job of .NET developer is that much in demand. So if you are on the position of the people who are out on the leading edge, now you have to gauge the investment of time in new technologies versus the work that people are trying to hand you for current technologies. The money is in doing stuff right now, the fun and the investment in future potential and credibility is in understanding what's going on out there. It's a very difficult balancing act to try to understand how much time to respectively invest in those two things, especially when we've got such widely different areas. From my perspective the four big areas we have to be concerned about are the there pieces of WinFX, which are Windows Presentation Foundation- WPF, Windows Communication Foundation- WCF/Indigo and WF - Work Flow. Those are part of the next generation framework which we will call WinFX. And the fourth technology is building in that 4GL-ish query technology into the languages into C Sharp and Visual Basic, that's called LINQ, Language INtegrated Query. There are four pretty big technologies now that we all have to figure out and I think everybody is going to have to find a different path depending upon what their areas of emphasis are. For me working in health care and needing the very best user interface that technology can provide, Avalon is very important to me. And I expect to spend quite a bit of time looking at it. By almost an accident I've spent the last couple of years working on very sophisticated workflow systems and because of that I want to understand what Windows Workflow does for me. But I have to be honest about that one: I think it's a little lower on the totem pole for most people, because it's really just an engine and there's a lot of stuff around it that would have to be developed to maturity before people look at it. There's Indigo for data transport and yes, I'm interested but they don't have tool ready for it yet. And I'm not really interested in the plumbing aspects; I don't want to be editing XML to use it. That I'm willing to put off and then LINQ, I expect to wait until there is a project in which I'm doing fairly sophisticated data manipulation before I learn LINQ in any significant depth.
10. What is it about Avalon that has you interested, what capabilities does it provide and what does it allow you to do that you couldn't do before?
Avalon is based in a world of varying resolutions, varying sizes, varying aspect ratios. Avalon being vector-based completely in its graphics instead of bit-mapped, and having an engine that has intelligence to rearrange things, to match the scale and size of the current app device, means that, for example in the health care world, I can have an application that runs on something small that doctors or other clinicians carry around and it could run on desktops and it could run on big monitor that are on the wall that the doctor might use to interact with the patient. All those possibilities are there from the point of view of scaling the interface and presenting in an appropriate fashion for all of them. I think Avalon is the technology we would use, because I don't think any of our technologies today would do that very well and I don't see others on the horizon that will. The second thing Avalon offers is the ability to conceive a user interface in a three-dimensional coordinate space. People are going to see this and get used to it even more quickly that you might realize, because some of the UI and VISTA, the next generation Windows, use that Avalon technology to render parts of the user interface in a tridimensional way so that you reach in and get everything that you want. I think there is enormous potential to apply that to the health care world because health care works with some of the most complicated information structures of any industry and it demands such a high level of usability and ease of use. You're not going to get a doctor to sit in a class for two weeks to learn how to use something. That's simply not going to happen. If you produce a system that functionally does what you want, but does present the user interface to a doctor, which he believes is appropriate and easy to use then he simply won't use it. So now we have what I hope are the technologies that would allow us to satisfy that level of user by providing entirely new paradigms for how you navigate through UI, for how you present the information they need to look at. The ideas are already spinning out, of people I talked to and some out of me, on how we would use this technique. I think health care would be one of the places where it can be the most aggressively applied.
11. Can you comment on the value of seeing information tridimensionally as you now can in Windows Vista?
I think the key thing to what Vista allows in terms of that tridimensional manipulation is that you can orient things in such a way that every thing you'd like to get to, at least part of it is there, that you can see. And there is the possibility that the user interface would allow certain movements of the camera, so to speak. So depending on what you are doing, you might be looking around from a different perspective and that leads to some interesting possibilities. But that means that there are some interesting implications for the kinds of peripherals that we are going to use with these kinds of systems. I think that scroll wheel on the mouse will become much much more important because you have to have something to navigate 3D and the buttons simply give you the 2D, I mean you might impose that 2D on a circle of some kind, but you still need the ability to navigate in 3D, and to me, probably, the example of an application that has taken this on at a fairly new level and made it work, is Google Earth where you navigate around with a mouse but you use that wheel to zoom in and out; I think that's a very basic example of the kind of user experience that I think Avalon would allow a wide variety of applications to implement.
12. What about 3d interfaces like in the Office applications?
That's right and very few applications implement that, but I think we're entering an era in which all the Microsoft mice sold in the last 4 or 5 years have that capability. So in the Microsoft world we'll be able to move in and out and I find myself wondering what the Mac folks are going to do? When 3 interfaces really become the way things are done, I'm wondering what their adaptation to that is going to be. They've got some bright minds; I'm sure they'll figure out something, but I think they are facing a bigger challenge than we are because we have peripheral and input devices.
13. We're already used to scrolling and right clicking and all that stuff.
Right. I mean for all I know the Apple guys will move to virtual gloves or something.
14. Someone brought that up in a talk and I'm thinking, especially in the medical industry where I've done some work, and there's a system where they put the CAT scans and the RMIs and the X-rays all together and they build up a tridimensional model, let's say of a spine they are going to operate on. Is this a valid way to navigate in a 3D manner?
That's exactly how it is. I think we're just at the very beginning of the possibility of using those kinds of virtual mapping things where you take something that uses a hand or whatever and reaches into the 3D space. I think we're at the very beginning of that, but the foundation for that is a user interface technology that first of all is a bit-mapped, because you would never be able to do it to do it; it has to be vector based, and it has to have the capability of doing things in a 3D coordinate space, both of which are build in he Avalon.
15. Workflow as another big thing and workflow right now is really hard to implement. How does WF address those type of issues? Or does it?
I'm not sure that workflow is going to get any easier from the perspective of how you put it in place. I don't think that WF is going to make a dramatic difference there. What WF is going to do is to allow more consistency into the engine, so for example today when you use this talk, there's a lot of integration work around constructing a workflow in this talk, and when this talk changes its engine to WF at some point in the future, that integration work would still be there. But what the workflow engine allows is for Microsoft to make it much more feasible for different products to have an engine that allows workflow. And then the tooling around that is what would eventually start to simplify the aspect of trying to get the workflow inside an organization. So WF itself isn't the answer there. It's what WF allows other people to build that will be the answer there, and there's a limit even there to what tools can do. Because when you start defining workflows and especially any workflow that touches on business processes and you're trying to automate something that's done manually now, the amount of work you have to do and the amount of requirements gatherings and understanding of the situation and the amount of coordination with what the users expect, I don't see how you make that substantially less than it is today. And that is a big part of the workflow job right now. It's too much trouble to get the technology working and WF will start to help. And the things that are built around it will start to help. Trying to get a group of people to do something with a consistent standardized workflow has its own challenges that are completely independent of the technology that you use.
16. So can we call Windows Workflow Foundation a sort of enabling technology that allows us to stop worrying about having a workflow engine and focus more on those difficult tasks?
I think that is probably a good way of putting it. The WF engine, which is not a product it's just a namespace, a piece of WinFX and it doesn't really has a lot of built in capabilities to talk to. For instance, one of the capabilities that I will have to have the first time I use it in a real app is the ability to talk to a queuing engine, and I'm probably going to use service broker capability for that. That's not in the box there's nothing that just plugs in and says "attach this workflow to that queue", so I have to write that. Fortunately in the context of WF you only have to write it once. And what I write will be reusable by a wide variety of people, much more so than when I wrote this complex flow engine plumbing stuff 2 years ago for a company that was automating workflow. None of that is portable to the outside world. None of it is reusable. I mean I can make it that way if I worked on it and productized it, but in the WF case it's a core around which other much more standardized pieces can eventually begin to build an ecosystem of more pluggable components that simplify the production of that infrastructure plumbing.
17. Ok Billy, thank you for taking the time to speak with us today. Do you have any final thoughts on the future of .NET development to share with our listeners?
I remember the summer of 2000, being in Orlando, seeing .NET introduced and being rather amazed at what it was capable of. And I felt like it would be the platform that we'd use for a minimum of 10 years, perhaps 15, and I've certainly seen no reason to change that for moving to the WinFX world. We are very much in need of an abstraction layer on top of that, conceptually similar to what Visual Basic provided for the old Windows API. Windows API was just too hard to use in the C world, and Visual Basic put an entirely new level of abstraction on top of it. But most of things you get out of a tool box, not something you wrote a bunch of code out of a template to do. We need a level of abstraction for the .NET framework that's similar to that and I think we'll see that although it is hard to predict exactly what it will look like or where it will come from. In the meantime Visual Basic and C Sharp just get better with every generation and they are the best tools I've ever used even though I recognize they are not the ideal tools for everybody in terms of that they require you to know a lot and I'm able to get more interesting things done, more innovating and more valuable things than I have ever had before. I think the gap between the people that are really able to use the tools and guys who just grind that code, that gap gets bigger every year with the technologies in .NET.
Community comments
Great Interview!
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Great Interview!
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I'm having a bit of a hardship understanding how I could possibly perform this operation.
float squared( float num ) { __asm { push ebp mov ebp, esp sub esp, num xorps xmm0, xmm0 movss dword ptr 4[ebp], xmm0 movss xmm0, dword ptr num[ebp] mulss xmm0, dword ptr num[ebp] movss dword ptr 8[ebp], xmm0 fld dword ptr 4[ebp] sqrtss xmm0, ebp movss ebp, xmm0 mov esp, ebp pop ebp ret 0 } }
I've worked in C / C++ for a while now, and it's always been a task of mine to really dig into how inline assembly works, but I'm having some problems when executing the code.
When I run this in my main function to print the root and insert a value, I'm given an error:
Exception thrown at 0x00000000 in Test.exe: 0xC0000005: Access violation executing location 0x00000000. occurred
Any ideas?
The most fundamental issue with this code is that you wrote your own function prologue and epilogue. You have to do that when you are writing .ASM files entirely by hand, but you have to not do that when you write "inline" assembly embedded in C. You have to let the compiler handle the stack. This is the most likely reason why the program is crashing. It also means that all of your attempts to access the
num argument will instead access some unrelated stack slot, so even if your code didn't crash, it would take a garbage input,
As pointed out in comments on the question, you also have a bunch of nonsensical instructions in there, e.g.
sqrtss xmm0, ebp (
sqrtss cannot take integer register arguments). This should have caused the compiler to reject the program, but if it instead produced nonsensical machine code, that could also cause a crash.
And (also as pointed out in comments on the question) I'm not sure what mathematical function this code would compute in the hypothetical scenario where each machine instruction does something like what you meant it to do, but it definitely isn't the square root.
Correct MSVC-style inline assembly to implement single-precision floating point square root, using the SSEn
sqrtss instruction, would look something like this, I think. (Not tested. Since this is Win32 rather than Win64, an implementation using
fsqrt instead might be more appropriate, but I don't know how to do that off the top of my head.)
float square_root(float radicand) { __asm { sqrtss xmm0, radicand } }
... Or you could just
#include <math.h> and use
sqrtf and save yourself the trouble.
I think using
fsqrt from scratch will work.
fld qword [num] fsqrt
User contributions licensed under CC BY-SA 3.0 | https://windows-hexerror.linestarve.com/q/so59740121-Square-root-ASM | CC-MAIN-2020-16 | refinedweb | 449 | 67.79 |
Python string join() function is used to concatenate a sequence of strings to create a new string.
Table of Contents
Python String join()
The basic syntax of Python join() function is like the below image.
Here str1 will be used as the separator between the concatenating elements of the sequenceOfString. Now, the following example will help you to visualize things.
# initialize the list of string str_list = ['My', 'favourite', 'fruit', 'is', 'banana'] # initialize the separator separator = '-' # use python string joint to join the words of the string output = separator.join(str_list) # print the output result print(output)
You will get the output like the following.
My-favourite-fruit-is-banana
Using A Single String Python Join Example
In the previous section, we used a list of string to join together. Now, what will happen if we use a single string instead of a list to join. Let’s see the next example. In this example, we will use space as separator. So the code will be like below.
# initialize the single string alphabets = 'abcdefghijklmnopqrstuvwxyz' # initialize the separator sep = ' ' # use python string joint to join that single string output = sep.join(alphabets) # print the output result print(output)
So the output will be
a b c d e f g h i j k l m n o p q r s t u v w x y z
Converting Python Join to a raw function
You should know that you can make your own function that can also do the same task that Python string join can do. In this section, we are going to see how to write that function.
If you look closely, you will see that the separator is appended after each item of the list except the last one. So we will write a function in which we will append the separator after each item.
After that, we will append the last item of the list to the result string. The following example will illustrate the idea.
def list_join(string_list, sep): result = '' for i in range(0, len(string_list)-1): result = result+string_list[i]+sep result = result+string_list[len(string_list)-1] return result # initialize the single string alphabets = 'abcdefghijklmnopqrstuvwxyz' # initialize the separator sep = ' ' # use python string joint to join that single string output = list_join(alphabets, sep) # print the output result print(output)
And you will get same output same as the output you got before with python join function.
a b c d e f g h i j k l m n o p q r s t u v w x y z
So, that’s all about python join function. Hope that you understand the topic clearly. If you have any query, feel free to comment below. Happy Learning.
Reference: Official Documentation
I visit your blog regularly to get new things like this. Thank you | https://www.journaldev.com/15174/python-join | CC-MAIN-2019-39 | refinedweb | 471 | 68.7 |
Dear all, During Debian SunCamp [1] we have moved the debian-ports archive from the old leda.debian.net machine to a DSA administrated machine called porta.debian.org. The software managing the archive, mini-dak, is still the same, however the whole is now better integrated in the debian.org namespace and with the mirror system. You will find the users visible changes below. APT archive ----------- The APT archive is now accessible on [2], which maps to 2 machines, one in The Netherlands and one in the USA. Here are the corresponding sources.list line: deb unstable main deb unreleased main and possibly: deb experimental main Redirections have been setup so that the old URLs still work, but they will not be kept permanently. In addition, given that the number of debian-ports users is relatively small, the mirror network has been dropped in favor of a CDN. It is not yet available, but it should be the case in the next hours or days. Please see the corresponding page for the details [3]. Uploading packages ------------------ People having upload rights should now upload packages to the ports-master.debian.org FTP server in the /incoming directory. CD images --------- CD images are now available on [4]. Again redirections have been setup. Web site -------- The debian-ports website is now available on [5] using HTTPS, and redirection from the various previous URL have been set up. The links and instructions on the web site have also been update, don't hesitate to report any broken link. We would like to thank to the DSA team and the SunCamp organizers for making that possible. Aurelien on behalf of the debian-ports team [1] [2] [3] [4] [5] -- Aurelien Jarno GPG: 4096R/1DDD8C9B aurelien@aurel32.net
Attachment:
signature.asc
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In ASP.NET Core MVC, a request URL is mapped to a controller's action. This mapping happens through the routing middleware and you can do good amount of customization. There are two ways of adding routing information to your application: conventional routing and attribute routing. This article introduces you with both of these approaches with the help of an example.
To understand how conventional and attribute routing works, you will develop a simple Web application, as shown in Figure 1.
Figure 1: A routing form
The Web page shown in Figure 1 displays a list of orders from the Orders table of the Northwind database. The launching page follows the default routing pattern: /controller/action. Every order row has Show Details links. This link, however, renders URLs of the following form:
/OrderHistory/CustomerID/order_year/order_month/order_day/OrderID
As you can see, this URL doesn't follow the default routing pattern of ASP.NET Core MVC. These URLs are handled by a custom route that we specify in the application. Clicking the Show Details link takes the user to another page, where order details such as OrderDate, ShipDate, and ShipAddress are displayed (see Figure 2).
Figure 2: Details for a customer's order
Let's develop this example and also discuss routing as we progress. The example uses Entity Framework Core for database access. Although we will discuss the EF Core code briefly, detailed discussion of EF Core is beyond the scope of this article. It is assumed that you are familiar with the basics of working with EF Core.
Okay. Create a new ASP.NET Core Web Application using Visual Studio. Because we want to use EF Core, add the NuGet package: Microsoft.EntityFrameworkCore.SqlServer. To add this package, right-click the Dependencies folder and select the "Manage NuGet Packages…" shortcut menu option. Then, search for the above-mentioned package and install it for your project.
Figure 3: Managing NuGet packages
Then, add a Models folder to your project root and add two class files into it: NorthwindDbContext.cs and Order.cs. Open the Order.cs file and add the following class definition to it.
[Table("Orders")] public class Order { [DatabaseGenerated(DatabaseGeneratedOption.Identity)] [Required] public int OrderID { get; set; } [Required] public string CustomerID { get; set; } [Required] public DateTime OrderDate { get; set; } [Required] public string ShipName { get; set; } [Required] public string ShipAddress { get; set; } [Required] public string ShipCity { get; set; } [Required] public string ShipCountry { get; set; } }
The Order class contains seven properties, namely: OrderID, CustomerID, OrderDate, ShipName, ShipAddress, ShipCity, and ShipCountry. The Order class is mapped to the Orders table by using the [Table] attribute.
Also, open the NorthwindDbContext class file and add the following code in it:
public class NorthwindDbContext : DbContext { public DbSet<Order> Orders { get; set; } protected override void OnConfiguring (DbContextOptionsBuilder optionsBuilder) { optionsBuilder.UseSqlServer("data source=.; initial catalog = northwind; integrated security = true"); } }
The NorthwindDbContext inherits from the DbContext class. Inside, it declares Orders DbSet. The OnConfiguring() method is used to configure the database connection string. Here, for the sake of simplicity, we pass a hard-coded connection string to the UseSqlServer() method. You also could have used dependency injection. Make sure to change the database connection string as per your setup.
Conventional Routing
Now, open the Startup.cs file and go to the Configure() method. The Configure() method is used to configure middleware. Somewhere inside this method, you will find the following code:
app.UseMvc(routes => { routes.MapRoute( name: "default", template: "{controller=Home}/ {action=Index}/{id?}"); });
The preceding code calls the UseMvc() method and also configures the default routing. Notice the MapRoute() call carefully. It defines a route named default and also specifies the URL template. The URL template consists of three parameters: {controller}, {action}, and {id}. The default value for the controller is Home, the default value foe action is Index, and the id is marked as an optional parameter.
If all you need is this default route, you also can use the following line of code to accomplish the same task:
app.UseMvcWithDefaultRoute();
This is the conventional way of defining routes and you can add your custom route definitions easily. Let's add another route that meets our requirement:
app.UseMvc(routes => { routes.MapRoute( name: "OrderRoute", template: "OrderHistory/{customerid}/{year}/ {month}/{day}/{orderid}", defaults: new { controller = "Order", action = "ShowOrderDetails" }); routes.MapRoute( name: "default", template: "{controller=Home}/{action=Index}/{id?}"); });
Notice the code marked in the bold letters. We added another route, named OrderRoute. This time, the URL template begins with static segment—OrderHistory— that won't change with each URL. Further, the URL template contains five parameters: {customerid}/{year}/{month}/{day}/{orderid}. The default parameter sets the default controller to Order and the default action to ShowOrderDetails.
Now that you have the desired route definition in place, it's time to create the HomeController and OrderController.
Add HomeController and OrderController to the Controllers folder by using the Add New Item dialog. The HomeController's Index() action is shown below:
public IActionResult Index() { using (NorthwindDbContext db = new NorthwindDbContext()) { return View(db.Orders.ToList()); } }
The Index() action simply passes a list of all the orders to the Index view for the sake of displaying in a table.
Next, add an Index view under Views > Home folder and write the following markup in it.
@model List<RoutingInAspNetCore.Models.Order> <html> <head> <title>List of Orders</title> </head> <body> <h2>List of Orders</h2> <table cellpadding="10" border="1"> <tr> <th>Order ID</th> <th>Customer ID</th> <th>Action</th> </tr> @foreach (var item in Model) { <tr> <td>@item.OrderID</td> <td>@item.CustomerID</td> <td>@Html.RouteLink("Show Details", "OrderRoute",new { customerid=item.CustomerID, year=item.OrderDate.Year, month=item.OrderDate.Month, day=item.OrderDate.Day, orderid=item.OrderID }) </td> </tr> } </table> </body> </html>
The Index view renders a table that lists OrderID and CustomerID of all the orders. Each order row has a link that points to the order details page. Notice how the link is rendered. We use the Html.RouteLink() helper to render this hyperlink. The first parameter of RouteLink() is the text of the hyperlink (Show Details, in this case). The second parameter is the name of the route as specified in the route definition (OrderRoute, in this case). The third parameter is an anonymous object holding all the values for the route parameters. In this case, there are five parameters: customerid, year, month, day, and orderid. The values of these parameters are picked from the corresponding Order object.
Okay. Now, open OrderController and add the ShowOrderDetails() action, as shown below:
public IActionResult ShowOrderDetails(string customerid, int orderid,int year,int month,int day) { ViewBag.Message = $"Order #{orderid} for customer {customerid} on {day}/{month}/{year}"; using (NorthwindDbContext db = new NorthwindDbContext()) { Order order = db.Orders.Find(orderid); return View(order); } }
The ShowOrderDetails() action takes five parameters corresponding to the route parameters. Inside, a message is stored in the ViewBag that indicates the OrderID, CustomerID, and OrderDate of the given order. Moreover, the code fetches the Order object from the Orders DbSet matching the OrderID. The Order object then is passed to the ShowOrderDetails view.
Now, add the ShowOrderDetails view to the Views > Order folder and add the following markup to it.
@model RoutingInAspNetCore.Models.Order <html> <head> <title>Orders Details</title> </head> <body> <h2>@ViewBag.Message</h2> <h2>Order Details</h2> @Html.DisplayForModel() </body> </html>
The ShowOrderDetails view simply outputs the Message ViewBag variable. All the properties of Order model object are outputted by using the DisplayForModel() helper.
This completes the application. Run the application, navigate to /Home/Index, and see whether the order listing is displayed. Then, click the Show Details link for an order and check whether order details are being shown as expected.
Attribute Routing
The previous example uses conventional routing. Now, let's use attribute routing to accomplish the same task.
First of all, comment out the existing UseMvc() call so that conventional routing is no longer enabled. Then, add the following call at that place:
app.UseMvc();
As you can see, the UseMvc() call no longer contains routing information. Then, open HomeController and add the [Route] attribute on top of it as shown next:
[Route("[controller]/[action]/{id?}")] public class HomeController : Controller { .... }
Now, the HomeController has been decorated with the [Route] attribute. The [Route] attribute defines the URL pattern using special tokens: [controller] and [action]. An optional id parameter also has been specified. This is equivalent to {controller}/{action}/{id} of the conventional routing.
If you want to set HomeController as the default controller and Index() as the default action, you would have done this:
public class HomeController : Controller { [Route("")] [Route("Home")] [Route("Home/Index")] public IActionResult Index() { .... } }
Here, the [Route] attribute has been added on top of the Index() action and sets the defaults as needed.
Okay. Then, open OrderController and add the [Route] attribute, as shown below:
[Route("OrderHistory/{customerid}/{year}/{month}/{day}/ {orderid}",Name ="OrderRoute")] public IActionResult ShowOrderDetails(string customerid, int orderid,int year,int month,int day) { .... }
Here, you added the [Route] attribute on top of the ShowOrderDetails() action. The [Route] attribute contains the same URL pattern as before. The name of the route also is specified by setting the Name property.
If you run the application, it should work as expected.
Route Constraints
You also can put constraints on the route parameters. Route constraints allow you to ensure that a route value meets certain criteria. For example, you may want to ensure that the CustomerID route value is a string with five characters. Or, the month value is between 1 and 12. You can add route constraints to both conventional routes as well as attribute routes. Let's see how.
Consider the following piece of code:
routes.MapRoute( name: "OrderRoute", template: "OrderHistory/{customerid:alpha:length(5)}/ {year:int:length(4)}/{month:int:range(1,12)}/ {day:int:range(1,31)}/{orderid:int}", defaults: new { controller = "Order", action = "ShowOrderDetails" }); [Route("{customerid:alpha:length(5)}/{year:int:length(4)}/ {month:int:range(1,12)}/{day:int:range(1,31)}/ {orderid:int}",Name ="OrderRoute")]
The preceding code shows how route constraints can be applied. The above example uses the following constraints:
- The alpha constraint is used to ensure that the value contains only alphabetical characters.
- The length(n) constraint is used to ensure that a value must have a length equal to the specified number.
- The int constraint is used to ensure that the value is an integer.
- The range(a,b) constraint is used to ensure that a value falls within certain a minimum and maximum range.
There are many more constraints available. A parameter can have more than one constraint attached with it. You can read more about route constraints here.
After adding these constraints, run the application, navigate to the order details page, and then change the CustomerID in the browser's address bar to some string more than 5 characters. Or, try changing the month to some number higher than 12. You will find that the request is rejected and doesn't reach the ShowOrderDetails() action.
Conclusion
This article examined how conventional and attribute routing of ASP.NET Core MVC work. You may learn more about routing here. The complete source code of the example we discussed in this article is also available for download. | http://mobile.codeguru.com/csharp/.net/net_asp/understanding-routing-in-asp.net-core-mvc.html | CC-MAIN-2017-34 | refinedweb | 1,871 | 57.87 |
TSContScheduleOnPool¶
Synopsis¶
#include <ts/ts.h>
- TSAction
TSContScheduleOnPool(TSCont contp, TSHRTime timeout, TSThreadPool tp)¶
Description¶
Schedules contp to run timeout milliseconds in the future, on a random thread that
belongs to tp. The timeout is an approximation, meaning it will be at least
timeout milliseconds but possibly more. Resolutions finer than roughly 5 milliseconds will
not be effective. Note that contp is required to have a mutex, which is provided to
TSContCreate().
The continuation is scheduled for a particular thread selected from a group of similar threads, as indicated by tp. If contp already has an thread affinity set, and the thread type of thread affinity is the same as tp, then contp will be scheduled on the thread specified by thread affinity.
In practice, any choice except
TS_THREAD_POOL_NET or
TS_THREAD_POOL_TASK is strongly not
recommended. The
TS_THREAD_POOL_NET threads are the same threads on which callback hooks are
called and continuations that use them have the same restrictions.
TS_THREAD_POOL_TASK threads
are threads that exist to perform long or blocking actions, although sufficiently long operation can
impact system performance by blocking other continuations on the threads..
Example Scenarios¶
Scenario 1 (no thread affinity info, different types of threads)¶
When thread affinity is not set, a plugin calls the API on thread “A” (which is an “ET_TASK” type), and wants to schedule on an “ET_NET” type thread provided in “tp”, the system would see there is no thread affinity information stored in “contp.”
In this situation, system sees there is no thread affinity information stored in “contp”. It then checks whether the type of thread “A” is the same as provided in “tp”, and sees that “A” is “ET_TASK”, but “tp” says “ET_NET”. So “contp” gets scheduled on the next available “ET_NET” thread provided by a round robin list, which we will call thread “B”. Since “contp” doesn’t have thread affinity information, thread “B” will be assigned as the affinity thread for it automatically.
The reason for doing this is most of the time people want to schedule the same things on the same type of thread, so logically it is better to default the first thread that it is scheduled on as the affinity thread.
Scenario 2 (no thread affinity info, same types of threads)¶
Slight variation of scenario 1, instead of scheduling on a “ET_NET” thread, the plugin wants to schedule on a “ET_TASK” thread (i.e. “tp” contains “ET_TASK” now), all other conditions stays the same.
This time since the type of the desired thread for scheduling and thread “A” are the same, the system schedules “contp” on thread “A”, and assigns thread “A” as the affinity thread for “contp”.
The reason behind this choice is that we are trying to keep things simple such that lock contention problems happens less. And for the most part, there is no point of scheduling the same thing on several different threads of the same type, because there is no parallelism between them (a thread will have to wait for the previous thread to finish, either because locking or the nature of the job it’s handling is serialized since its on the same continuation).
Scenario 3 (has thread affinity info, different types of threads)¶
Slight variation of scenario 1, thread affinity is set for continuation “contp” to thread “A”, all other conditions stays the same.
In this situation, the system sees that the “tp” has “ET_NET”, but the type of thread “A” is “ET_TASK”. So even though “contp” has an affinity thread, the system will not use that information since the type is different, instead it schedules “contp” on the next available “ET_NET” thread provided by a round robin list, which we will call thread “B”. The difference with scenario 1 is that since thread “A” is set to be the affinity thread for “contp” already, the system will NOT overwrite that information with thread “B”.
Most of the time, a continuation will be scheduled on one type of threads, and rarely gets scheduled on a different type. But when that happens, we want it to return to the thread it was previously on, so it won’t have any lock contention problems. And that’s also why “thread_affinity” is not a hashmap of thread types and thread pointers.
Scenario 4 (has thread affinity info, same types of threads)¶
Slight variation of scenario 3, the only difference is “tp” now says “ET_TASK”.
This is the easiest scenario since the type of thread “A” and “tp” are the same, so the system schedules “contp” on thread “A”. And, as discussed, there is really no reason why one may want to schedule the same continuation on two different threads of the same type.
Note
In scenario 3 & 4, it doesn’t matter which thread the plugin is calling the API from. | https://docs.trafficserver.apache.org/en/latest/developer-guide/api/functions/TSContScheduleOnPool.en.html | CC-MAIN-2020-40 | refinedweb | 798 | 63.32 |
Source: The Samsung Graphics 2D driver (/dev/fimg2d) is accessible by unprivileged users/applications. It was found that the ioctl implementation for this driver contains a locking error which can lead to memory errors (such as use-after-free) due to a race condition. The key observation is in the locking routine definitions in fimg2d.h: #ifdef BLIT_WORKQUE #define g2d_lock(x) do {} while (0) #define g2d_unlock(x) do {} while (0) #define g2d_spin_lock(x, f) spin_lock_irqsave(x, f) #define g2d_spin_unlock(x, f) spin_unlock_irqrestore(x, f) #else #define g2d_lock(x) mutex_lock(x) #define g2d_unlock(x) mutex_unlock(x) #define g2d_spin_lock(x, f) do { f = 0; } while (0) #define g2d_spin_unlock(x, f) do { f = 0; } while (0) #endif This means that the g2d_lock/g2d_unlock routines are no-ops when BLIT_WORKQUE is defined, which appears to be the default configuration. Unfortunately the alternative spin lock routines are not used consistently with this configuration. For example, the FIMG2D_BITBLT_BLIT ioctl command (with notes annotated as "PZ"): ctx = file->private_data; /* PZ: ctx allocated at open(), lives on the heap. */ switch (cmd) { case FIMG2D_BITBLT_BLIT: mm = get_task_mm(current); if (!mm) { fimg2d_err("no mm for ctx\n"); return -ENXIO; } g2d_lock(&ctrl->drvlock); /* PZ: This is a no-op. */ ctx->mm = mm; ret = fimg2d_add_command(ctrl, ctx, (struct fimg2d_blit __user *)arg); if (ret) { ... } ret = fimg2d_request_bitblt(ctrl, ctx); /* PZ: Does stuff with the ctx. */ if (ret) { ... } g2d_unlock(&ctrl->drvlock); /* PZ: Another no-op */ As the lock macros are no-ops, a second process can change ctx->mm when the original process is still using the same ctx->mm (as long as it has access to the same file descriptor). Reproduction steps: Open /dev/fimg2d Fork to get two processes with different mm’s with the access to the fd Concurrently call the FIMG2D_BITBLT_BLIT ioctl from both processes. One ioctl should have valid data, the other should fail At this point ctx->mm will now have invalid or free data (free if the forked process dies). Proof-of-concept code to trigger this condition is attached (fimg2d-lock.c) Proof of Concept:
Related ExploitsTrying to match CVEs (1): CVE-2015-7891
Trying to match OSVDBs (1): 129526
Other Possible E-DB Search Terms: Samsung fimg2d | https://www.exploit-db.com/exploits/38557/ | CC-MAIN-2017-26 | refinedweb | 360 | 58.62 |
In addition to multiple inheritance, you will also encounter situations where you will inherit from a class that is, in turn , inheriting from another class. In fact, later in this book, when we get to Visual C++ , you will see a lot of this. Essentially if your class is derived from a class, you inherit all its protected and public members, even if those members were inherited from yet another class. You can have inheritance going back any number of classes and you will have inherited it all.
Step 1: Enter the following code into your favorite text editor.
#include < iostream > using namespace std; class baseclass1 { public: void basefunc1(); }; void baseclass1::basefunc1() { cout << "This is in the first base class \n"; } class baseclass2: public baseclass1 { public: void basefunc2(); }; void baseclass2::basefunc2() { cout << "This is in the second base class \n"; } class baseclass3: public baseclass2 { public: void basefunc3(); }; void baseclass3::basefunc3() { cout << "This is in the third base class\n"; } class derivedclass : public baseclass3 { }; int main () { derivedclass myclass; myclass.basefunc1(); myclass.basefunc1(); myclass.basefunc3(); return 0; }
Step 2: Compile and execute your program.
You should see something much like what is depicted in Figure 12.4.
Figure 12.4: Indirect inheritance.
You can see that the derived class you actually used has access to all the public functions it inherited from each class. This example shows several layers of indirect inheritance.
As you have previously seen, you can make a pointer to any data type. And as we have already discussed, a class is simply a data type, it’s just a lot more complicated than most. This means you can use pointers to classes. You have already seen an example shown with the transfermoney function. Recall that the purpose of a class is to take the data and functions that work on the data and encapsulate them together. If you require a function to have access to both data and functions, it is only logical to pass it a pointer to a class.
The pointer to a class operates just like the pointer to a structure. You use the - > operator rather than the . operator to access the various members of the class pointer. The following brief code segment illustrates this.
void funca(myclass *myobj) { myobj->element1; myobj->element2; }
As you can see, a pointer to a class works much like a pointer to a structure. The use of class pointers can be powerful because it allows you to pass an entire class, with all its data and methods , into a function. And because you are using a pointer, you don’t need to worry about returning all those values.
Before we can delve into the topic of abstract classes, we must first explore what a virtual function is. A virtual function is a function that, if inherited, must be overridden.
Let us examine exactly what this means. In a class, you may have one or more functions. If you inherit from that class you have the choice of either using the inherited function as it exists in the base class or overriding it.
You create virtual functions by adding the word virtual to their declaration as shown in the following example.
virtual void funca();
With virtual functions, if you simply create an instance of the class they are in, then the function is treated as any other normal function. However, if the class is inherited, then the virtual function must be overwritten. The following code segment illustrates this.
class someclass { public: virtual void funca(); }; void someclass::funca() { cout << "This is my function in the base class\n"; } class anotherclass { public: void funca(); } void anotherclass::funca() { cout << "This is in my derived class \n"; } int main() { someclass a; anotherclass b; a.funca(); b.funca(); return 0; }// end of main
As you can see, if you create an instance of this class, then you can use the function as its written; if you inherit from this class, then the derived class will have to write its own implementation. If you don’t override the function in the derived class, you will get a compiler error. Another way of looking at virtual functions is to realize that they have no effect on the class they are in. They only affect classes that inherit from that class. If the base class that contains the virtual function is instantiated , then the virtual function behaves just like any other ordinary function. However, if some class inherits from a base class that contains a virtual function, then the derived class will have to override the virtual function.
An abstract class is a class defining an interface only; used as a base class. An abstract class cannot be instantiated. It can only be inherited from. Declaring a member function of a class as a pure virtual function makes the class abstract and prevents creation of objects of the abstract class. Another way to say this is to state that an abstract class is a class that cannot be instantiated, but must be inherited from. An abstract class is created by making any of its member functions a pure virtual function. The way you create a pure virtual function is simply by adding an =0 at the end of the function.
virtual void funca() = 0;
The how of creating an abstract class is actually rather simple. It is the why that is problematic . The reason for creating an abstract class is so that you can have a base class that, although it is not appropriate to be used directly, can be inherited. You create an abstract class by making one of its functions a pure virtual function. Remember that a pure virtual function is created by adding =0 to the end of a virtual function’s prototype as you see in the following example.
class abstract { public: virtual void pure_v_func() = 0; };
Step 1: Enter this code into your favorite text editor and save it as 12_05.cpp.
#include < iostream > using namespace std; class abstract { public: virtual void pure_v_func() = 0; }; class derived: public abstract { public: void pure_v_func(); }; void derived::pure_v_func() { cout << "See how this works"; } int main () { derived myclass; myclass.pure_v_func(); return 0; }
You see how we now have an abstract base class. This is due to the fact that it contains a pure virtual function. This means you now cannot directly instantiate the class. It also means that all the classes methods must be overwritten in the derived class. The purpose of the abstract class is to force the derived class to have a given interface. Other programming languages, such as Java, use an object type called interface to accomplish this. In C++, the abstract class does the same thing. You can think of an abstract class as a template that determines the specific interface that its derived classes will have, while leaving the implementation up to the derived class. | http://flylib.com/books/en/2.331.1.100/1/ | CC-MAIN-2013-20 | refinedweb | 1,141 | 61.67 |
Hi,
I was just typing a LaTeX document inside Sublime and I wonder how to launch ie "pdflatex" on it.I had a look at the docs, but "build", "exec" etc. are not documented.
Thanks for any suggestion.
you can use python's os.system() in a python plugin.
for example:
[code]import sublime, sublimepluginimport osclass MyPluginCommand(sublimeplugin.TextCommand): def run(self, view, args): f = view.fileName(); result = os.system("parser.exe " + f)
def isEnabled(self, view, args):
return True[/code]
Thanks for the suggestion vim, I've tried but got problems.
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import sublime, sublimeplugin
import os
class PdfLatexCommand(sublimeplugin.TextCommand):
def run(self, view, args):
f = view.fileName()
print "the file is %s"%f
result = os.system("pdflatex " + f)
def isEnabled(self, view, args):
return True
(pdflatex is in my PATH so I don't need to put the ".exe" behind it).I've binded the command to a key, but nothing seems to happen.
So, I've tried to do a 'LaTeX.sublime-build' file with this (I took it from the Haskell one):
buildCommand exec "^(...*?):([0-9]*):?([0-9]*)" pdflatex.exe '"$File"'
It works, but in fact I really don't know what I'm doing. What's the regexp "^(...?):([0-9]):?([0-9]*)" for ? And now that my file ie "myfile.tex" has been compiled to "myfile.pdf", how to call my reader on it ? $File returns the file name, I need it without its extension + "pdf" ($File:-3]+"pdf" in Python). It must exist other variables like $File, but what are their names ?
I know it's pain to write documentation, but Sublime really needs better docs (the wiki has become unreadable). We can all help jps on this point, I think it's no problem.
regarding the first method i suggested maybe you need to add:
class MyPluginCommand(sublimeplugin.TextCommand):
def run(self, view, args):
f = view.fileName();
exe = sublime.packagesPath()
exe = os.path.join(exe, "User")
exe = os.path.join(exe, "MyParser.exe")
# Spaces in path workaround:
# add an extra quote (!) before the quoted command name:
# result = os.system('""pythonbugtest.exe" "test"')
# Explanation:
# there was a time when the cmd prompt treated all spaces as delimiters, so
# >cd My Documents
# would fail. Nowadays you can do that successfully and even
# >cd My Documents\My Pictures
# works.
# In the old days, if a directory had a space, you had to enclose it in quotes
# >cd "My Documents"
# But you didn't actually need to include the trailing quote, so you could get away with
# >cd "My Documents
cmd = '""%(exe)s" "%(args)s""' % {'exe' : exe, 'args' : f } # stderr > out.txt 2>&1
result = os.system(cmd)
that what i have used once and it worked. regarding the other method, i must admit it seems cleaner, but i can join your feelings here, i also don't have a clue how it works (i stumbled on it once, but couldn't figure it out)
I recommend using a Makefile for these sort of things, when I'm working with pdfs, I use a Makefile along the lines of:
foo.pdf: foo.tex
pdfclose --all
pdflatex -interaction=nonstopmode foo.tex
pdfopen --file foo.pdf
The requires you to have make installed (e.g., from cygwin), and pdfopen/pdfclose (availble from a few places, magic.aladdin.cs.cmu.edu/2005/07 ... -pdfclose/ is one).
The syntax of sublime-build files is:
buildCommand exec error-regex command [args].
The regex matches file names in the output of the command, typically compiler errors messages. Submatch 1 should be the filename, 2 the line number, and 3 the column (the latter two being optional). The regex must be quoted, and any escapes within it double-escaped.
I'm not happy with the syntax of *.sublime-build files, it's on the todo list to make them more reasonable.
Here's some snippets from my pdflatex compile command. Should be almost everything you need.
#
# COMPILE LATEX AND LAUNCH ACROBAT
#
def compilePdf(latexFile):
miktexExe = miktexCommandPath("pdflatex")
commandLine = " --interaction=nonstopmode --aux-directory c:\\temp\\ \"" + latexFile + "\""
# two compiles, to make sure contents etc are up-to-date
for i in range(2):
print runSysCommand(miktexExe, commandLine)
pdf = os.path.splitext(latexFile)[0] + ".pdf"
print "pdf created at '%s'" % pdf
subprocess.Popen(pdf, shell=True)
#
# RUN EXE AND GET OUTPUT
#
def getOutputOfSysCommand(commandText, arguments=None):
"""Returns the output of a command, as a string"""
print "getting output of %s %s" % (commandText, arguments)
p = subprocess.Popen([commandText, arguments], shell=True, bufsize=1024, stdout=subprocess.PIPE)
p.wait()
stdout = p.stdout
return stdout.read()
#
# WHERE DOES MIKTEX LIVE?
#
def miktexCommandPath(commandName):
return os.path.join(programFiles(), "MiKTeX 2.7\\miktex\\bin", commandName + ".exe")
#
# WHERE ARE PROGRAM FILES?
#
def programFiles():
prog32 = "c:\\program files"
prog64 = "c:\\program files (x86)"
if os.path.exists(prog64):
return prog64
elif os.path.exists(prog32):
return prog32
else:
raise Exception("can't find a program files")
Thanks for all your answers,
jps : thanks for clarifying these points, I know now what the regexps are for. I wasn't aware of pdfopen/pdfclose : nice tool !
SteveCooperOrg : I'll try to adapt it to my needs as I'm using TeXLive 2008 on Windows. | https://forum.sublimetext.com/t/launching-an-external-process/125/4 | CC-MAIN-2016-44 | refinedweb | 866 | 60.61 |
Below is a python script that executes a linux bash command "echo Hello World > ./output"
import os
os.system("bash -c \"echo Hello World > ./output\"");
import java.io.IOException;
public class callCommand {
public static void main(String[] args) {
try {
Process p = Runtime.getRuntime().exec(
new String[]{"bash","-c",
"\"echo Hello World > ./output\""});
} catch(IOException e) {
e.printStackTrace();
}
}
}
The extra quotes around
echo ... should be removed:
Process p = Runtime.getRuntime().exec(new String[]{ "bash", "-c", "echo Hello World > ./output" });
The python version needs extra quotes to tell the underlying system that
echo Hello World > ./output is a single argument. The java version explicitly specifies arguments as separate strings, so it doesn't need those quotes.
Also, your version doesn't "run without complaint", you just don't see the complaints, because you don't read the error stream of the created process. | https://codedump.io/share/zX76dsTtEdwS/1/using-java39s-getruntimeexec-to-run-a-linux-shell-command-how | CC-MAIN-2017-09 | refinedweb | 141 | 62.54 |
by Aswin M Prabhu
How to build a real-time chatroom with Firebase and React (Hooks)
If you are into front-end development, I bet you know what react is. It has become the most popular front-end framework and does not appear to be slowing down. Firebase is a back-end service created by Google that enables developers to rapidly iterate on their applications without worrying about run of the mill stuff like authentication, database, storage.
Firebase has two database options, both of which have awesome real-time capabilities. For example, you can subscribe to changes in a document stored in firebase cloud firestore with the following JavaScript snippet.
db.collection("cities").doc("SF") .onSnapshot(function(doc) { console.log("Current data: ", doc.data()); });
The callback provided to the
onSnapshot() function fires every time the document changes. Local writes from your app will fire it immediately with a feature called latency compensation.
React Hooks are an upcoming react feature that let you use state and other react features without writing a class. They’re currently in react v16.7.0-alpha. Building this app is a great way to explore the future of react with react hooks.
The final product will be an IRC like global chatroom app where we first ask the user to enter a nickname. Simple.
Scaffolding
A new react app can easily be created with the official create-react-app cli tool with the following terminal commands (react hooks need react and react-dom v16.7.0-alpha).
npm i -g create-react-appcreate-react-app react-firebase-chatroomcd react-firebase-chatroomnpm i -S [email protected] [email protected]
The firebase setup is pretty straight forward as well. Create a new project from the firebase console. Setup the firebase real-time database in test mode. Initialize the local project with firebase-tools command. Choose the realtime-database and hosting as the enabled features. Select
build as the public directory. Every other option can be left as is.
npm i -g firebase-toolsfirebase-tools initnpm i -S firebase
It might need you to login before you can initialize the repository.
The database structure will look like the following.
Building the app using good old class based components
React hooks are still an experimental feature and the API might change in the future. So let us first look at how the app can be build with class based components. I went with only the
App component because the application logic was simple enough.
The user will be prompted to join with a nickname and an email if the
joined variable is
false . It is initially set to false in the
constructor .
constructor() { super(); this.state = { joined: false, nickname: "", email: "", msg: "", messages: {}, }; this.chatRoom = db.ref().child('chatrooms').child('global'); this.handleNewMessages = snap => { console.log(snap.val()); if (snap.val()) this.setState({ messages: snap.val() }); }; }
componentDidMount() { this.chatRoom.on('value', this.handleNewMessages); }
componentWillUnmount() { this.chatRoom.off('value', this.handleNewMessages); }
All the messages are initially fetched from firebase in the
componentDidMount life cycle method. The
on method on a db ref takes an event type and a callback as arguments. Every time a user sends a new message and updates the database, the
handleNewMessages function receives a snapshot of the updated data and updates the state with the new messages. We can unsubscribe from the database updates in the
componentWillUnmount life cycle method using the
off method on the db ref.
A message can be sent by appending the message to the chatroom ref on the database. The
push method of the ref generates a unique id for the new entry and appends it to the existing data.
this.chatRoom.push({ sender: this.state.nickname, msg: this.state.msg,});
The messages are rendered by looping over the
messages object.
{Object.keys(this.state.messages).map(message => { if(this.state.messages[message]["sender"] === this.state.nickname) // render the user's messages else // render messages from other users})}
The final
App component will look like this.
Migrating to react hooks
The simplest hook is the
useState hook. It takes the initial state and returns the state variable and a function that lets you update it. This function acts as a replacement for
this.setState . For example the nickname state logic can be modified as follows.
const [nickname, setNickname] = useState("");const handleNameChange = e => setNickname(e.target.value);...// during render<input placeholder="Nickname" value={nickname} onChange={handleNameChange} />
The next challenge is to find a place for the logic inside the life cycle methods. This is where the
useEffect hook comes in. This is where we perform logic that has side effects. It can be thought of as a combination of all the life cycle methods.
useEffect can also optionally return a function that is used to clean up (like unsubscribe to an event).
useEffect(() => { const handleNewMessages = snap => { if (snap.val()) setMessages(snap.val()); } chatRoom.on('value', handleNewMessages); return () => { chatRoom.off('value', handleNewMessages); };});
Subscription and unsubscription were related pieces of logic that were split into different life cycle methods. Now they are put together in a single hook. Using different
useEffect hooks for different side effects enables separation of concerns.
By default,
useEffect runs both after the first render and after every update.
One of the major advantages of using hooks is that stateful logic can be reused between components. For example, imagine you want to reuse email input handling and validating logic in multiple components. A custom hook can achieve this as shown below. A custom hook is a function that can call other hooks and starts with “use”. Starting with “use” is not a rule but a very important convention.
function useEmail(defaultEmail) { const [email, setEmail] = useState(defaultEmail); const [isValidEmail, setValidEmail] = useState(defaultEmail);
function validateEmail(email) { const re = /^(([^<>()\[\]\\.,;:\[email protected]"]+(\.[^<>()\[\]\\.,;:\[email protected]"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/; return re.test(String(email).toLowerCase()); }
function handleEmailChange(e) { if (validateEmail(e.target.value)) { setValidEmail(true); } setEmail(e.target.value); } return { email, handleEmailChange, isValidEmail };}
And in your components you can use the custom hook as shown below.
// in your componentsconst { email, handleEmailChange, isValidEmail } = useEmail("")...<input value={email} value={email} onChange={handleEmailChange} />// show error message based on isValidEmail
Custom hooks also make it easier to unit test a piece of logic independent of the components that use the hook.
The final
App component looks as follows.
There’s more to read on hooks
Find the final app with bare minimum styling.
Thanks for reading and happy hacking!
Find me on Twitter and GitHub. | https://www.freecodecamp.org/news/how-to-build-a-real-time-chatroom-with-firebase-and-react-hooks-eb892fa72f1e/ | CC-MAIN-2019-43 | refinedweb | 1,095 | 50.33 |
Satpy internal workings: having a look under the hood¶
Querying and identifying data arrays¶
DataQuery¶
The loading of data in Satpy is usually done through giving the name or the wavelength of the data arrays we are interested in. This way, the highest, most calibrated data arrays is often returned.
However, in some cases, we need more control over the loading of the data arrays. The way to accomplish this is to load data arrays using queries, eg:
scn.load([DataQuery(name='channel1', resolution=400)]
Here a data array with name channel1 and of resolution 400 will be loaded if available.
Note that None is not a valid value, and keys having a value set to None will simply be ignored.
If one wants to use wildcards to query data, just provide ‘*’, eg:
scn.load([DataQuery(name='channel1', resolution=400, calibration='*')]
Alternatively, one can provide a list as parameter to query data, like this:
scn.load([DataQuery(name='channel1', resolution=[400, 800])]
DataID¶
Satpy stores loaded data arrays in a special dictionary (DatasetDict) inside scene objects. In order to identify each data array uniquely, Satpy is assigning an ID to each data array, which is then used as the key in the scene object. These IDs are of type DataID and are immutable. They are not supposed to be used by regular users and should only be created in special circumstances. Satpy should take care of creating and assigning these automatically. They are also stored in the attrs of each data array as _satpy_id.
Default and custom metadata keys¶
One thing however that the user has control over is which metadata keys are relevant to which datasets. Satpy provides two default sets of metadata key (or ID keys), one for regular imager bands, and the other for composites. The first one contains: name, wavelength, resolution, calibration, modifiers. The second one contains: name, resolution.
As an example here is the definition of the first one in yaml:
data_identification_keys: name: required: true wavelength: type: !!python/name:satpy.dataset.WavelengthRange resolution: calibration: enum: - reflectance - brightness_temperature - radiance - counts transitive: true modifiers: required: true default: [] type: !!python/name:satpy.dataset.ModifierTuple
To create a new set, the user can provide indications in the relevant yaml file. It has to be provided in header of the reader configuration file, under the reader section, as data_identification_keys. Each key under this is the name of relevant metadata key that will used to find relevant information in the attributes of the data arrays. Under each of this, a few options are available:
-
required: if the item is required, False by default
-
type: the type to use. More on this further down.
-
enum: if the item has to be limited to a finite number of options, an enum can be used. Be sure to place the options in the order of preference, with the most desirable option on top.
-
default: the default value to assign to the item if nothing (or None) is provided. If this option isn’t provided, the key will simply be omitted if it is not present in the attrs or if it is None. It will be passed to the type’s convert method if available.
-
transitive: whether the key is to be passed when looking for dependencies of composites/modifiers. Here for example, a composite that has in a given calibration type will pass this calibration type requirement to its dependencies.
If the definition of the metadata keys need to be done in python rather than in a yaml file, it will be a dictionary very similar to the yaml code. Here is the same example as above in python:
from satpy.dataset import WavelengthRange, ModifierTuple id_keys_config = {'name': { 'required': True, }, 'wavelength': { 'type': WavelengthRange, }, 'resolution': None, 'calibration': { 'enum': [ 'reflectance', 'brightness_temperature', 'radiance', 'counts' ], 'transitive': True, }, 'modifiers': { 'required': True, 'default': ModifierTuple(), 'type': ModifierTuple, }, }
Types¶
Types are classes that implement a type to be used as value for metadata in the DataID. They have to implement a few methods:
-
a convert class method that returns it’s argument as an instance of the class
-
__hash__, __eq__ and __ne__ methods
-
a distance method the tells how “far” an instance of this class is from it’s argument.
An example of such a class is the
WavelengthRange class.
Through its implementation, it allows us to use the wavelength in a query to find out which of the
DataID in a list which has its central wavelength closest to that query for example.
DataID and DataQuery interactions¶
Different DataIDs and DataQuerys can have different metadata items defined. As such we define equality between different instances of these classes, and across the classes as equality between the sorted key/value pairs shared between the instances. If a DataQuery has one or more values set to ‘*’, the corresponding key/value pair will be omitted from the comparison. Instances sharing no keys will no be equal.
Breaking changes from DatasetIDs¶
-
The way to access values from the DataID and DataQuery is through getitem: my_dataid[‘resolution’]
-
For checking if a dataset is loaded, use ‘mydataset’ in scene, as ‘mydataset’ in scene.keys() will always return False: the DatasetDict instance only supports DataID as key type.
Creating DataID for tests¶
Sometimes, it is useful to create DataID instances for testing purposes. For these cases, the satpy.tests.utils module now has a make_dsid function that can be used just for this:
from satpy.tests.utils import make_dataid did = make_dataid(name='camembert', modifiers=('runny',)) | https://satpy.readthedocs.io/en/latest/dev_guide/satpy_internals.html | CC-MAIN-2020-40 | refinedweb | 907 | 53.1 |
Why do I write articles for ACCU you might ask? Well, if truth be told, it's not as altruistic as it appears: I write to learn! Writing forces me to order my thoughts (which generally end up slightly less disorganised :-). Readers send me feedback which usually sparks new thoughts. This ties in with John's last editorial "We are all continually learning and re-learning, and that process isn't just listening and reading, it's speaking and writing". To try and convince you of this I'm going to write about what I learned from my own Overload 29 article. I hope this will convince some of you out there that writing articles is in your own self interest. Now, where to start? Something trivial
date::date(int dd, int mm, int ccyy) : day(dd), month(mm), year(ccyy) { // empty }
Constructors often do all they need to in their member initialisation list. Not unreasonable, since constructors do initialisation. The comment tries to emphasise that the null body is not accidental. While reading this empty comment I recalled a classically bad comment (don't laugh now, wait till you see it real code)
value++; // increment value
As I thought about it I realised my empty comment was almost exactly the same! It wasn't conveying the message I wanted it to: that the body is deliberately empty. How to say this succinctly? For now I've settled on
// all done
Here's some more ado about nothing. I noticed my previous article contained code fragments that used ... in place of large chunks of code. This is visually confusing as catch-all handlers also use ellipses[1]. So I'm trying something different.
namespace accu { class string { public: char & operator[](size_t index); const char & operator[](size_t index) const; ... ... ... }; }
Just after this fragment (again from my previous article) I wrote "An alternative version of the const array-subscript operator could return a plain char (by value). There is not much to choose between the two, ..." While reading this paragraph I decided to it would be useful to list just what differences there are. There is a difference worth highlighting. Consider
const char & example() { const string greeting("Hello"); return greeting[0]; }
If the const subscript operator returns a char reference then example will return a dangling const reference to the initial char of greeting which will go out of scope when example returns. Ooops. However, if the const subscript operator returns a value
char string::operator[](size_t index) const;
the example function will return a const reference to a copy of the initial char of greeting, and all is well. As I write this article I've noticed the previous article said "array-subscript operator". What have arrays to do with this? Nothing. It's the string subscript operator. Terminology matters.
A reader asked whether the use of size_t as the index type for the subscript operator might be slower than using a plain (signed) int. I can see the thinking behind this. size_t could be typedef'd to be an unsigned long, leading to the question of whether long arithmetic is slower than int arithmetic. Does it matter? It might; it depends on the context. However my primary concern when writing code is that my code mirrors my intent. As Dan Saks put it so eloquently at the ACCU conference "Say it in Code". size_t is sensible for a string subscript parameter. It says a negative value doesn't make sense in this context. But suppose the application needs to be speeded up, profiling shows the string subscript operator to be a prime candidate for optimisation, and a test reveals the plain int version is indeed quicker. Would I change the size_t to an int in the subscript operators? Well, yes and no. I'd be tempted to try
namespace accu { class string { public: // types class position { ... ... ... }; public: char & operator[](position index); char operator[](position index) const; ... ... ... }; }
and give string::position lots of checking. This would force clients to write
for ( string::position index = 0; index != limit; ++index) { ... ... ... }
but would allow me to redeclare position if I wanted to
typedef int position; // OR // typedef size_t position;
In my code the smart-reference class nested inside string was called char_reference. A sharp eyed reader asked why I'd used the name char_reference and not just reference? After all, the standard STL containers have a nested type called reference.
namespace std { template<typename type> // simplified class vector { public: typedef ... ... ... reference; ... ... ... }; }
With a moment's reflection you will quickly see that in a template container you cannot name the type that reference is a reference to because that is the name of the template parameter type, which of course will vary. My string class is not a template class, and is not constrained in this way. I can chose any name for the smart-reference class and still be "conforming" with a simple typedef
namespace accu { class string { public: class char_reference; typedef char_reference reference; // idiomatic public: char_reference operator[](size_t index); char operator[](size_t index) const; ... ... ... }; class string::char_reference { public: ... ... ... }; }
In the article my string::char_reference class looked like this...
namespace accu { ... ... .. class string::char_reference { ... ... ... private: string & s; size_t index; }; }
Ugh, s is an awful variable name. Something like target is much more expressive. But should it be a reference? Why not a pointer? I think it's perfectly reasonable for the string client to write
string::reference marker = greeting[0];
and I can see the wisdom of using a pointer data member to emphasise the association between two separate objects with separate (but related) lifetimes. On the other hand a reference has to be initialised and cannot be re-bound. But using a reference might confuse the reader: they might think the smart reference class is making the raw reference data member smart and the size_t data member is just some extra unrelated gubbins. Of course I could make the pointer const. On balance I think I prefer the pointer version.
namespace accu { ... ... .. class string::char_reference { public: char_reference(string *target,size_t index); // default copy constructor OK public: char_reference operator=(char new_value); operator char () const; private: string * const target; size_t index; }; }
As I write this I wonder why index is not also const.
string * const target; const size_t index;
So, why not this?
string * const target; size_t const index;
That somehow seems clearer.
Some string behaviour was not covered in the previous article. Obvious examples are comparison and input/output. Here's how I would do output
namespace accu { class string { ... ... ... public: // primitive output void write(ostream & out) const; }; // idiomatic output ostream & operator<< (ostream &out,const string & to_write); };
and the implementation would be
namespace accu // string : input/output { // primitive output void string::write(ostream & out) const { ... ... ... } // idiomatic output ostream & operator<< (ostream & out, const string & s) { s.write(out); return out; } }
The use of << and >> as streaming operators is very specific to C++. It's easy to forget this. The difference between primitives and idioms is important. Primitives seem right during early design, idioms during late design, as a refinement. It also seems right that the idioms do nothing except forward to the primitive (just like << forwards to write). I mention this in nauseous detail because it relates strongly to the last section of the article where I discussed the pro's and con's of making string::assign public or private. Looking at this again I realise this is really the same primitive/idiom idea.
void example(accu::string & s) { // this is the primitive use s.assign(0, 'J'); s[0] = 'J'; // this is idiomatic use }
This has helped me make up my mind. I've settled on making string::assign public, and removing the friendship. I've just noticed a tiny bit of hungarian notation in my previous article
void string::assign(size_t index,char new_ch);
Slap. In my defence I plead that I wrote the article tight to the copy deadline. Here's a fragment of the "final" version. The primitive and idiomatic access methods are declared together in their own section. The implementation code chunks at the same section level.
namespace accu { class string { public: class char_reference; typedef char_reference reference; ... ... ... public: // access, idiomatic and primitive char_reference operator[](size_t index); char operator[](size_t index) const; void assign(size_t index, char new_value); private: ... ... ... }; class string::char_reference { public: char_reference (string *target,size_t index); ... ... ... private: string * const target; size_t const index; }; } // string : access, primitive and idiomatic namespace accu { // primitive void string::assign (size_t index, char new_value) { bounds_check(index); unshare_state(); text[index] = new_value; } // idiomatic string::char_reference string::operator[](size_t index) { return char_reference(this, index); } char string::operator[](size_t index) const { bounds_check(index); return text[index]; } } // string::char_reference - assignment namespace accu { string::char_reference string::char_reference::operator= (char new_value) { target->assign(index, new_value); return *this; } string::char_reference:: operator char() const { // this was ro in the previous article // a needless abbreviation const string & readonly = *target; return readonly[index]; } }
I'm constantly amazed just how often apparently simple code benefits from further simplification. The above is simpler than the previous article in two ways. The unfettered use of primitives is one. The other is the visual separation of the two class definitions. In other words, I don't write
namespace accu { class string { public: class char_reference { ... ... ... }; ... ... ... }; }
Here's a thought. Should the char_reference conversion operator be const? Suppose someone writes
const string::char_reference eh = s[0]; cout << eh << endl;
In an expression a reference will automatically "decay" into the thing it is a reference to: a reference is implicitly const, so the explicit const is meaningless. However, if the conversion operator was non-const the second line would no longer compile. This is a step too far. Don't forget code such as
void parameter (const string::char_reference & ah) { cout << ah << endl; }
or (and this is a clincher), code like this
template<typename type> void parameter(const type & ah) { cout << ah << endl; }
In the article I wrote the subscript operator with the & token and the operator token together. A comment from Sean Corfield made me re-look at this. He pointed out that Stroustrup consistently uses a different style, one where the char token and the & token have no intervening whitespace. It's easier to see it than read it
// Previous article version char &operator[](size_t index); // Stroustrup version char& operator[](size_t index); // This article. I'm trying it out char & operator[](size_t index);
To take the simplest example, lets look at this bit of C
int answer = 42; int *ptr = &answer *ptr = answer;
This is how Kernighan and Ritchie declare pointers in their white book[2]. They decided to make the syntax of a declaration mirror the syntax of an expression. Hence the * and the ptr are together in both. The effect is the declaration emphasises how to use the identifier in an expression. Which is exactly the point I think they intended. But in C++ I think Stroustrup would write
int answer = 42; int* ptr = &answer; *ptr = answer;
Why the difference? Well, Stroustrup emphasises the type of ptr in the declaration of ptr. Which again is exactly the point I think he intends. In other words in C the focus is on expressions, whereas in C++ the focus is on types. A natural consequence of this is that Stroustrup never declares more than one pointer in a declaration. If he did he would have to write something like
int* ptr, *another; / version 1
Note however that Stroustrup is quite happy to declare more than one value in a single declaration[3]. How would Stroustrup declare two pointers of the same type? Perhaps he'd write this
int* ptr; // version 2 int* another;
Is this different to version 1? In a sense it is. In version 1 if I change int to double I'm changing the type of ptr and the type of another. To change them both in version 2 I have to edit twice. In effect version 1 is saying ptr and another are deliberately the same type, whereas version 2 is saying ptr and another are coincidentally the same type. Of course you could write
typedef int* int_pointer; int_pointer ptr, another;
Another point of interest is that all the introductory QA C++ courses use a third style using two spaces...
int * ptr = ...; int & ref = ...;
The rationale is simple. We want each token to be clearly visible: we don't really want to lexically bind the asterisk to the type name "more" than to the identifier name. After all, C++ newcomers have enough to cope with as it is!
That's all for now. | https://accu.org/index.php/journals/552 | CC-MAIN-2020-29 | refinedweb | 2,087 | 55.54 |
Created on 2020-06-30 23:10 by godot_gildor, last changed 2020-07-31 08:58 by vinay.sajip.
The logging.config module uses three internal data structures to hold items that may need to be converted to a handler or other object: ConvertingList, ConvertingTuple, and ConvertingDict.
These three objects provide interfaces to get converted items using the __getitem__ methods. However, if a user tries to iterate over items in the container, they will get the un-converted entries.
This is a change in behaviour, so probably needs to be added to future versions only.
I think the other issue here is that the ConvertingX classes aren't documented apart from comments in the code where they are defined.
> I think the other issue here is that the ConvertingX classes aren't documented apart from comments in the code where they are defined.
That's deliberate - they're considered an internal implementation detail.
If you are going to make them public general purpose classes you need to implement also support of slices, __reversed__(), index(), remove(), count(), sort(), copy() in ConvertingList and more methods in ConvertingTuple, and ConvertingDict.
If it is not goal then I think that no any changes are needed. If they are internal classes they needed only features which are used internally by the module code.
> If it is not goal
I don't have a goal to make these part of a documented API. OP, can you share a use case where you need to iterate over these internal structures?
I encountered the need for the iterators when trying to create a subclass of the QueueHandler class that would manage both the QueueHandler and the QueueListener. The implementation is very similar to that described in this Medium post:
Both the original poster and I encountered one small issue: when using a dictConfig to instantiate the new subclass, the main QueueHandler gets a ConvertingList of the handlers that the user has requested be used. The subclass would then pass these to the QueueListener, but the constructor for the QueueListener takes *handlers (that is, it will convert the ConvertingList to a tuple). Unfortunately, because ConvertingList does not expose the iterator, converting from the ConvertingList to the tuple results in a tuple of unconverted handler references (ultimately strings).
The author of the Medium article gets around this by creating a little function that simply loops over the length of the ConvertingList and does a "get" on each item on the list, to ensure that the item is converted. Since ConvertingList is not documented though, there is concern that this approach could break in the future if the interface changes etc.
With the implementation of the iterator in this PR, the conversion of the ConvertingList to the tuple will automatically result in a tuple of converted handlers, so one doesn't need to know about the ConvertingList object - it handles things behind the scenes.
Here is the code that the Medium article currently uses to force conversion:
def _resolve_handlers(l):
if not isinstance(l, ConvertingList):
return l
# Indexing the list performs the evaluation.
return [l[i] for i in range(len(l))]
OK, seems like a reasonable use case. I haven't looked at the PR yet, as it still has a "CLA not signed" label, and I normally wait until the CLA is signed before looking more closely at PRs.
Thanks.
I don't know why it still says CLA not signed - I signed it a week ago, but I'll try to figure that out this week.
O.K. CLA is now signed and if I check on the "check-yourself" with my github user it is showing that I have signed it now.
Just wanted to check-in to see if there were any updates on my proposed PR?
Thanks for the PR. I reviewed it and requested changes about 3 weeks ago - you should have received a notification from GitHub when that happened. | https://bugs.python.org/issue41177 | CC-MAIN-2020-34 | refinedweb | 656 | 57.1 |
What's new in v1.2.11
Main Changes:
- Support for PlayFab Servers 2.0
- Support for Source Control Systems
- Force Public Binding Endpoint of Game Server
- New Thread Pool Manager
For a full list of changes, check the log here.
Support For PlayFab Servers 2.0
In this version we've extended the support to cloud hosting services to include the new Azure PlayFab Servers 2.0, also known as Thunderhead. The PlayFab integration grants to you the option to run Headless servers inside the Azure infrastructure, spin news servers on-the-fly and retrieve metrics from your servers from the main dashboard.
You can find more information about the integration on our dedicated page and also on the PlayFab Sample. It shows how to build a working headless server running directly on the PlayFab VMs and a client capable of connecting to the game server.
Support For Source Control Systems
Photon Bolt now include support to Source Control Systems integrated with the Unity Editor, like Perforce and others that use the VersionControl.Provider API to synchronize files.
By default the support is disabled, so it will not interphere on the normal usage of Bolt, but if your team make use of such tool, you can enable it on the
Bolt Settings window, at the
Miscellaneous section, on the
Enable Source Provider Integration checkbox.
Force Public Binding Endpoint Of Game Server
Photon Bolt has built-in procedure capable of discovering the public IP and PORT of the peer running the SDK, it makes usage of the STUN protocol. This is useful and necessary in order to accomplish the punch-through between the game server and the client, creating a direct connection. The procedure works fine in most of the network scenarios and grants lower delays among the players.
Unfortunately, this behavior will not work on 100% of the cases, mostly because the game server is running on a very constrained network configuration, that is the case on some hosting service providers, corporative infrastructures, universities, as examples. For those cases, Bolt has now the option to force the public endpoint of the local peer. This configuration is only useful if you are able to get this information at the startup of your game server or it's fixed for the current server.
Here is shown how to inform Photon Bolt which endpoint it should use as it's public IP:PORT configuration. The endpoint information is sent to any client trying to connect to this server in order to try the punch procedure.
public class Menu : Bolt.GlobalEventListener { private void Awake() { BoltLauncher.SetUdpPlatform(new PhotonPlatform(new PhotonPlatformConfig() { ForceExternalEndPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 1234) })); } }
New Thread Pool Manager
In order to improve the memory allocation and power consumption, it was created a new Thread Pool manager, responsible for the creation and management of Threads inside the SDK.
It guarantees an on-demand initialization, recycling, and destruction of Threads.
This is mainly useful in some restricted platforms like the mobile targets and consoles like Nintendo Switch (that has limited usage of Threads).
The Thread Pool controls all threads used by the SDK, those are focused on running the network updates and maintaining the background connections. | https://doc.photonengine.com/zh-CN/bolt/current/dev-log/new-in-1211 | CC-MAIN-2022-05 | refinedweb | 537 | 52.29 |
First time here? Check out the FAQ!
I suspect it was removed because C++ has long had the same functionality in std::sort.
For the use shown, add (if not already there)
#include <algorithm>
and replace the macro with
static void
icvSortDistances( int *array, size_t total, int /*unused*/ )
{
std::sort( &array[0], &array[total] );
}
If you want to use the 'aux' parameter (passing info in to the compare) with std::sort, you need to define a little class with a method bool operator ()( T,T) const; you can put data in that class when constructing an instance of it, and you then pass the instance as a 3rd param to std::sort. That sort will call the operator() method to do compares, thus that method will be able to see the data. The operator()( a,b) should implement a<b for your sort - assuming you want increasing results.
bool operator ()( T,T) const;
operator()( a,b)
a<b
Likewise if you want to sort e.g. floats in decreasing abs. value, you can make a little empty class with just the appropriate bool operator( float a , float b )const { return std::abs(a) > std::abs(b);} and pass an instance of that class as the 3rd parameter.
bool operator( float a , float b )const { return std::abs(a) > std::abs(b);} | https://answers.opencv.org/users/22285/gregsmith_to/?sort=recent | CC-MAIN-2020-24 | refinedweb | 221 | 59.64 |
Elastic::Model::Role::Doc - The role applied to your Doc classes
version 0.28
$doc = $domain->new_doc( user => { id => 123, # auto-generated if not specified email => 'clint@domain.com', name => 'Clint' } ); $doc->save; $uid = $doc->uid;
$doc = $domain->get( user => 123 ); $doc = $model->get_doc( uid => $uid );
$doc->name('John'); print $doc->has_changed(); # 1 print $doc->has_changed('name'); # 1 print $doc->has_changed('email'); # 0 dump $doc->old_values; # { name => 'Clint' } $doc->save; print $doc->has_changed(); # 0
$doc->delete; print $doc->has_been_deleted # 1
Elastic::Model::Role::Doc is applied to your "doc" classes (ie those classes that you want to be stored in Elasticsearch), when you include this line:
use Elastic::Doc;
This document explains the changes that are made to your class by applying the Elastic::Model::Role::Doc role. Also see Elastic::Doc.
The following attributes are added to your class:
The uid is the unique identifier for your doc in Elasticsearch. It contains an index, a type, an id and possibly a routing. This is what is required to identify your document uniquely in Elasticsearch.
The UID is created when you create your document, eg:
$doc = $domain->new_doc( user => { id => 123, other => 'foobar' } );
index: initially comes from the
$domain->name- this is changed to the actual domain name when you save your doc.
type: comes from the first parameter passed to new_doc() (
userin this case).
id: is optional - if you don't provide it, then it will be auto-generated when you save it to Elasticsearch.
Note: the
namespace_name/type/ID of a document must be unique. Elasticsearch can enforce uniqueness for a single index, but when your namespace contains multiple indices, it is up to you to ensure uniqueness. Either leave the ID blank, in which case Elasticsearch will generate a unique ID, or ensure that the way you generate IDs will not cause a collision.
$type = $doc->type; $id = $doc->id;
type and
id are provided as convenience, read-only accessors which call the equivalent accessor on "uid".
You can defined your own
id() and
type() methods, in which case they won't be imported, or you can import them under a different name, eg:
package MyApp::User; use Elastic::Doc; with 'Elastic::Model::Role::Doc' => { -alias => { id => 'doc_id', type => 'doc_type', } };
$timestamp = $doc->timestamp($timestamp);
This stores the last-modified time (in epoch seconds with milli-seconds), which is set automatically when your doc is saved. The
timestamp is indexed and can be used in queries.
These private attributes are also added to your class, and are documented here so that you don't override them without knowing what you are doing:
A boolean indicating whether the object has had its attributes values inflated already or not.
The raw uninflated source value as loaded from Elasticsearch.
$doc->save( %args );
Saves the
$doc to Elasticsearch. If this is a new doc, and a doc with the same type and ID already exists in the same index, then Elasticsearch will throw an exception.
Also see Elastic::Model::Bulk for bulk indexing of multiple docs.
If the doc was previously loaded from Elasticsearch, then that doc will be updated. However, because Elasticsearch uses optimistic locking (ie the doc version number is incremented on every change), it is possible that another process has already updated the
$doc while the current process has been working, in which case it will throw a conflict error.
For instance:
ONE TWO -------------------------------------------------- get doc 1-v1 get doc 1-v1 save doc 1-v2 save doc1-v2 -> # conflict error
If you don't care, and you just want to overwrite what is stored in Elasticsearch with the current values, then use "overwrite()" instead of "save()". If you DO care, then you can handle this situation gracefully, using the
on_conflict parameter:
$doc->save( on_conflict => sub { my ($original_doc,$new_doc) = @_; # resolve conflict } );
See "has_been_deleted()" for a fuller example of an "on_conflict" callback.
The doc will only be saved if it has changed. If you want to force saving on a doc that hasn't changed, then you can do:
$doc->touch->save;
If you have any unique attributes then you can catch unique-key conflicts with the
on_unique handler.
$doc->save( on_unique => sub { my ($doc,$conflicts) = @_; # do something } )
The
$conflicts hashref will contain a hashref whose keys are the name of the unique_keys that have conflicts, and whose values are the values of those keys which already exist, and so cannot be overwritten.
See Elastic::Manual::Attributes::Unique for more.
$doc->overwrite( %args );
"overwrite()" is exactly the same as "save()" except it will overwrite any previous doc, regardless of whether another process has created or updated a doc with the same UID in the meantime.
$doc->delete;
This will delete the current doc. If the doc has already been updated to a new version by another process, it will throw a conflict error. You can override this and delete the document anyway with:
$doc->delete( version => 0 );
The
$doc will be reblessed into the Elastic::Model::Deleted class, and any attempt to access its attributes will throw an error.
$bool = $doc->has_been_deleted();
As a rule, you shouldn't delete docs that are currently in use elsewhere in your application, otherwise you have to wrap all of your code in
evals to ensure that you're not accessing a stale doc.
However, if you do need to delete current docs, then "has_been_deleted()" checks if the doc exists in Elasticsearch. For instance, you might have an "on_conflict" handler which looks like this:
$doc->save( on_conflict => sub { my ($original, $new) = @_; return $original->overwrite if $new->has_been_deleted; for my $attr ( keys %{ $old->old_values }) { $new->$attr( $old->$attr ): } $new->save } );
It is a much better approach to remove docs from the main flow of your application (eg, set a
status attribute to
"deleted") then physically delete the docs only after some time has passed.
$doc = $doc->touch()
Updates the "timestamp" to the current time.
Has the value for any attribute changed?
$bool = $doc->has_changed;
Has the value of attribute
$attr_name changed?
$bool = $doc->has_changed($attr_name);
Note: If you're going to check more than one attribute, rather get all the "old_values()" and check if the attribute name exists in the returned hash, rather than calling has_changed() multiple times.
\%old_vals = $doc->old_values();
Returns a hashref containing the original values of any attributes that have been changed. If an attribute wasn't set originally, but is now, it will be included in the hash with the value
undef.
$terms = $doc->terms_indexed_for_field( $fieldname, $size );
This method is useful for debugging queries and analysis - it returns the actual terms (ie after analysis) that have been indexed for field
$fieldname in the current doc.
$size defaults to 20.
These private methods are also added to your class, and are documented here so that you don't override them without knowing what you are doing:
Inflates the attribute values from the hashref stored in "_source".
The raw doc source. | http://search.cpan.org/~drtech/Elastic-Model-0.28/lib/Elastic/Model/Role/Doc.pm | CC-MAIN-2015-06 | refinedweb | 1,151 | 56.59 |
Found some minor nits in your .xsd and .xml files, fixed files are attached
with this message.
_____
Eric Ye * IBM, JTC - Silicon Valley * ericye@locus.apache.org
----- Original Message -----
From: "Andrew Newton" <anewton@netsol.com>
To: <general@xml.apache.org>
Sent: Wednesday, July 19, 2000 11:23 AM
Subject: Schemas and Namespaces
> I'm trying to use an XML schema with a namespace and seem to be doing
> something wrong. I took the personal.xsd and personal-schema.xml
> documents in the data/ and added namespaces to them, but I keep getting
> a "grammar not found" error message (running java dom.DOMCount -v
> test-personal-schema.xml).
>
> I've included the modified files and the output.
>
> What am I doing wrong?
>
> -Andy Newton
>
----------------------------------------------------------------------------
----
> ---------------------------------------------------------------------
> In case of troubles, e-mail: webmaster@xml.apache.org
> To unsubscribe, e-mail: general-unsubscribe@xml.apache.org
> For additional commands, e-mail: general-help@xml.apache.org | http://mail-archives.apache.org/mod_mbox/xml-general/200007.mbox/%3C004901bff1b8$9c608170$e3170609@cupertino.ibm.com%3E | CC-MAIN-2015-22 | refinedweb | 153 | 54.79 |
This artcle is also available as a PDF download.
Microsoft Small Business Server 2003 offers small organizations, and even many medium-size ones, all the server firepower they require. A seemingly no-brainer good deal, SBS offers potent Windows architecture, scalability, and industry standard components (Exchange, SQL, Outlook) in a reasonably priced product.
Before you roll it out, though, here are a few elements to keep in mind.
#1: 75 Users and/or devices is the max
Windows Small Business Server 2003 is a great deal—that is, as long as your organization consists of no more than 75 users or devices. If your business already has 50 employees and is growing quickly, you'll likely want to turn to Windows Server 2003 instead. But if your organization won't be crossing the 50- or 60-employee mark any time in the next two years or so, SBS 2003 may well prove perfect for your needs.
#2: There are two versions
Selecting the wrong version of Windows Small Business Server 2003 can be expensive. Not only does a reinstallation and network reconfiguration take considerable time, but it can eat up much of a licensing budget as well. Make sure you select the proper version for your organization when you deploy SBS 2003.
The two versions are Standard and Premium. Windows Small Business Server 2003 Standard Edition includes the Windows Server 2003 operating system plus Windows SharePoint Services v2, Exchange Server 2003, Outlook 2003, and Microsoft's Shared Fax Service. At $599, that's a sweet deal.
SBS 2003 Premium Edition includes everything in the Standard Edition, plus SQL Server 2000, ISA Server 2004 and FrontPage 2003. Most folks won't be throwing in the additional $900 (the Premium Edition runs $1,499) for FrontPage, which Microsoft's moving away from. Instead, it's the SQL Server database and ISA Server 2004 firewall most organizations seek when purchasing the Premium Edition.
Review your organization's requirements and choose accordingly. Upgrading from Standard to Premium (Microsoft part number T75-00140) will cost you $900 (so you won't save anything), and it'll cost you a bunch of time.
#3: Five CALs is standard
When calculating your licensing costs and requirements, bear in mind that SBS 2003 includes five client access licenses (CALs). Additional licenses can be purchased in packs of fives and 20s. Five packs retail for $489, while 20-packs sell for $1,929. Open License buyers typically pay $460 and $1,841, respectively, while Open License/Software Assurance customers pay $690 and $2,761. Transition and upgrade CALs are also available at varying prices (depending upon the platform from which you're migrating and the number of upgrades you require).
#4: There are two types of CALs
When planning your SBS 2003 deployment, be careful about the types of CALs you purchase. You have two choices: Device and User licenses. Device CALs cover any device (such as a PC, handheld device, or server) that accesses the Small Business Server. User CALs, on the other hand, cover users who access the Small Business Server.
Whichever you select, each device and user that accesses a Small Business Server must possess a Small Business Server 2003 CAL. The only exception is unauthenticated users accessing SBS' Web services.
Device CALs come in handy when you have multiple users accessing the same PCs in shifts. User CALs tend to work best when a single user accesses the server from multiple devices.
Should you make the wrong choice, you're still in luck. Microsoft permits changing license type. But beware: You can change from user CALs to device CALs (or vice versa) only once.
#5: Use the wizards
The best way to break Windows Small Business Server 2003 is to try configuring systems and processes manually. Don't do it. Use the numerous wizards provided within the operating system to do everything from configuring Internet access to administering e-mail accounts.
#6: Leverage the To Do List
Small Business Server 2003 tracks your installation and setup process with a comprehensive To Do List. At first glance, the list appears somewhat superfluous. You've been administering systems for years, right? You don't need a reminder list, do you?
Check your ego at the door. Manual transmissions are more fun to drive, sure, but automatics are easier. There's nothing wrong with opting for some simplified engineering. So simplify your server deployment and let the To Do List walk you through the configuration process. You're less likely to skip an important step, and the list places timesaving shortcuts at the ready.
From configuring the server's Internet connection and activating the server to configuring performance reports and backup routines, take advantage of the resources Microsoft's included in the operating system. Don't just close or minimize the To Do List every time it appears. Make a conscientious effort to complete all the list's tasks. The server will run more smoothly, and likely more securely, as a result.
#7: Select the internal name carefully
Despite Microsoft's recommendations, don't use .LOCAL as part of the SBS domain's internal name. Apple began using .LOCAL with the second iteration of the OS X platform. Trying to add Macintosh systems to an SBS domain that contains .LOCAL as part of its name can create conflicts. Although there are workarounds, avoid the problem altogether by selecting a namespace (such as .LAN) that won't create conflicts should Macs need to be added.
Further, avoid using your company's routable domain name () as an internal name, because that triggers a host of DNS issues. Internal DNS queries perform best when routed exclusively within the internal domain. If a routable public Internet domain name is used, additional configuration and maintenance is required to enable local systems to access local resources. Skip those headaches; select a unique, non-publicly routed internal name for your SBS 2003 deployment.
#8: SBS prefers multiple NICs
Small Business Server 2003 likes to work with multiple NICs. The system will nag you repeatedly if you don't configure your SBS box with two network cards, as Microsoft's designed the OS to provide effective firewall and routing protections. However, at least two NICs are required to leverage those protective capacities.
Ultimately, SBS prefers for you to connect one NIC to your Internet connection and the other network interface to your LAN via a switch. With the two interfaces in place, SBS 2003 can then filter and firewall traffic between the Internet and your LAN, thereby providing an additional layer of security between your organization's systems, data, and resources and the public.
#9: You need not jump on the R2 bandwagon
First it was released, then it wasn't. Microsoft released Windows Small Business Server 2003 R2 and even began promoting it to its partners. However, there was one small problem. It wasn't ready for prime time. So, Microsoft pulled it back. R2 was originally released in mid-July; IT professionals now must wait until the start of the third quarter for the final release.
R2's new features include a "Green Check," which helps monitor and update systems, simplified update management, and enlarged mailbox limits. If your small business doesn't require those features, however, I recommend you stick with SBS 2003. Let others test the new release and workout the bugs for you. You can always upgrade when the first service pack rolls out.
#10: When you do jump on the R2 bandwagon, the ride may be cheap
Those hosting Small Business Server 2003 SP1 installations can migrate to SBS 2003 R2 by contacting Microsoft and completing a request for a Microsoft Windows Small Business Server 2003 R2 Upgrade Media Kit. Eligibility requirements can be found on Microsoft's Web site. The kit itself, which includes an R2 Technologies CD, two Premium Technologies CDs (for Premium Edition license holders), a Getting Started poster, and a Certificate of Authenticity for the Upgrade, is free; all you pay is a minor fee for shipping and handling.
Software Assurance customers, meanwhile, may obtain the new R2 OS and need not purchase a new server license. Even non-Software Assurance clients aren't out of luck. Microsoft will offer those clients an upgrade option. To be eligible, customers just need be upgrading from a wide variety of SBS platforms (4.0, 4.5, 2000 and 2003 are all eligible). | http://www.techrepublic.com/article/10-things-you-should-know-before-deploying-microsoft-windows-small-business-server-2003/ | CC-MAIN-2017-43 | refinedweb | 1,404 | 55.34 |
ICMAKE Part 4
Three examples will be given in this final section, completing our discussion of icmake. The first example illustrates a `traditional make script', used with icmake. The example was taken from the `callback utility', developed by Karel (and also available from beatrix.icce.rug.bl). The second example is a simple dos2unix script which may be used to convert DOS textfiles to Unix textfiles: it uses awk to do the hard work. Finally, the attic-move script is presented, implementing a non-destructive remove, by moving files into an `attic.zip'. More examples can be found in the icmake distribution tar.gz file. The examples are annotated by their own comment, and are presented as they are currently used.
#!/usr/local/bin/icmake -qi #define CC "gcc" #define CFLAGS "-c -Wall" #define STRIP "strip" #define AR "ar" #define ARREPLACE "rvs" #define DEBUG "" #define CALLBACKDIR "/conf/callback" #define BINDIR "/usr/local/bin" #define VER "1.05v int compdir (string dir) { int i, ret; list ofiles, cfiles; string hfile, curdir, cfile, ofile, libfile; curdir = chdir ("."); libfile = "lib" + dir + ".a"; hfile = dir + ".h"; chdir (dir); if (hfile younger libfile) cfiles = makelist ("*.c"); else cfiles = makelist ("*.c", younger, libfile); for (i = 0; i < sizeof (cfiles); i++) { cfile = element (i, cfiles); ofile = change_ext (cfile, ".o"); if (! exists (ofile) || ofile older cfile) exec (CC, DEBUG, CFLAGS, cfile); } if (ofiles = makelist ("*.o")) { exec (AR, ARREPLACE, libfile, "*.o"); exec ("rm", "*.o"); ret = 1; } chdir (curdir); return (ret); } void linkprog (string dir) { chdir (dir); exec (CC, DEBUG, "-o", dir, "-l" + dir, "-lrss", "-L. -L../rss"); chdir (".."); } void buildprogs () { int cblogin, cbstat, rss; chdir ("src"); cblogin = compdir ("cblogin"); cbstat = compdir ("cbstat"); rss = compdir ("rss"); if (cblogin || rss) linkprog ("cblogin"); if (cbstat || rss) linkprog ("cbstat"); chdir (".."); } void instprog (string prog, string destdir) { chdir ("src/" + prog); exec (STRIP, prog); exec ("chmod", "700", prog); exec ("cp", prog, destdir); chdir ("../.."); } void install () { buildprogs (); instprog ("cblogin", CALLBACKDIR); instprog ("cbstat", BINDIR); } void cleandir (string dir) { chdir ("src/" + dir); exec ("rm", "-f", "*.o lib*.a", dir); chdir ("../.."); } void clean () { exec ("rm", "-f", "build.bim"); cleandir ("cblogin"); cleandir ("cbstat"); cleandir ("rss"); } void makedist () { list examples; int i; clean (); chdir ("examples"); examples = makelist ("*"); for (i = 0; i < sizeof (examples); i++) if (exists ("/conf/callback/" + element (i, examples)) && "/conf/callback/" + element (i, examples) younger element (i, examples)) exec ("cp", "/conf/callback/" + element (i, examples), element (i, examples)); chdir (".."); exec ("rm", "-f", "callback-" + VER + ".tar*"); exec ("tar", "cvf", "callback-" + VER + ".tar", "*"); exec ("gzip", "callback-" + VER + ".tar"); exec ("mv", "callback-" + VER + ".tar.z", "callback-" + VER + ".tar.gz"); } void main (int argc, list argv) { if (element (1, argv) == "progs") buildprogs (); else if (element (1, argv) == "install") install (); else if (element (1, argv) == "clean") clean (); else if (element (1, argv) == "dist") makedist (); else { printf ("\n" "Usage: build progs - builds programs\n" " build install - installs program\n" " build clean - cleanup .o files etc.\n" "\n" " build dist - makes .tar.gz distrib file\n" "\n"); exit (1); } exit (0); }
#!/usr/local/bin/icmake -qi /* DOS2UNIX This script is used to change dos textfiles into unix textfiles. */ string pidfile; void usage(string prog) { prog = change_ext(get_base(prog), ""); // keep the scriptname printf("\n" "ICCE ", prog, ": Dos to Unix textfile conversion. Version 1.00\n" "Copyright (c) ICCE 1993, 1994. All rights reserved\n" "\n", prog, " by Frank B. Brokken\n" "\n" "Usage: ", prog, " file(s)\n" // give help "Where:\n" "file(s): MS-DOS textfiles to convert to UNIX textfiles\n" "\n"); exit (1); // and exit } void dos2unix(string file) { if (!exists(file)) printf("'", file, "' does not exist: skipped\n"); else { printf("converting: ", file, "\n"); exec("/bin/mv", file, pidfile); system("/usr/bin/awk 'BEGIN {FS=\"\\r\"}; {print $1}' " + pidfile + " > " + file); } } void process(list argv) { int i; // make general scratchname pidfile = "/tmp/dos2unix." + (string)getpid(); echo(OFF); // no echoing of exec-ed progs for (i = 1; i < sizeof(argv); i++) dos2unix(element(i, argv)); // convert dos 2 unix if (exists(pidfile)) exec("/bin/rm", pidfile); // remove final junk } int main(int argc, list argv) { if (argc == 1) usage(element(0, argv)); process(argv); // process all arguments return (0); // return when | http://www.linuxjournal.com/article/2794?quicktabs_1=0 | CC-MAIN-2014-10 | refinedweb | 674 | 64.61 |
Rescale pixel intensities of an image in Python
In this tutorial, we will see how to rescale the pixel intensities of image.
Colour images are arrays of pixel values of RED, GREEN, and BLUE. These RGB values range from 0 – 255.
Every pixel will have an RGB value depending on the intensities of these colours. Now to process these images with RGB pixel values is a huge task, especially in the field of machine learning where huge chunks of data are processed. So it is very important to rescale simpler pixel values for the ease of computation.
How to rescale pixel intensities of an image in Python?
Firstly let’s import necessary modules
import matplotlib.pyplot as plt from numpy import asarray from PIL import Image
Now we will get the image. Note that the image is in still in the form of pixels we need to convert it into arrays.
image = Image.open('image path') print(image.mode) plt.imshow(image) image_pixels=asarray(image)
Here we have used pillow module to open the image and numpy function asarray to convert into arrays.
The output looks like this
RGB
credits: wallpaperplay.com
Now we will see what are the maximum and minimum and the mean pixel densities we have got.
std=image_pixels.std()
print(std,”std”)
mean=image_pixels.mean()
print(image_pixels.max(),”max”)
print(image_pixels.min(),”min”)
print(mean,”mean”)
OUTPUT
91.78171626356098 std 255 max 0 min 109.53139837139598 mean
Since we have got the mean values we will subtract the mean value from all the pixel values.
And then divide them by the standard deviation of the pixel values.
mean_pixels=image_pixels-mean mean_std_pixels=mean_pixels/std
Now we have got the rescaled pixel values. | https://www.codespeedy.com/rescale-pixel-intensities-of-an-image-in-python/ | CC-MAIN-2022-27 | refinedweb | 285 | 58.58 |
Anyways, the idea is the following: you want to change the class attributes before it becomes final -- there are things you just can't do in Python after a class is already declared (Python uses this technique for creating properties -- in my specific use-case I'm using it to overcome some limitations that Django has in its model inheritance with fields, but I've already used this many times).
The idea is the following: you get the frame which is being used inside the class declaration and change the locals in it so that the final created class will have the things you declared.
I.e.: This code:
import sys def prototype_class(frame=None): if frame is None: frame = sys._getframe().f_back frame.f_locals['new_attribute'] = 'New attribute' class MyNewClass(object): prototype_class() print MyNewClass().new_attribute
Is the same as:
class MyNewClass(object): new_attribute = 'New attribute'
-- Just more complicated and more flexible -- in my case, it'll properly help me to choose how to create and customize the fields of a Django model class without having to copy and paste a bunch of code.
On a separate note, blogspot just sucks for code... why can't they simply create an option to add a piece of code? I'm now manually putting my code in html as described in -- it'd certainly be trivial for the blogspot devs to put a button which would do that for me right? (colors would be nicer, but this is the easiest things that just works for me and I'd already settle for it if blogger added it -- I know blogger has the quotes, but I want the code at least on a box with a monospaced font).
8. | http://pydev.blogspot.com/2012/12/prototyping-class-in-python.html?showComment=1355866349284 | CC-MAIN-2014-52 | refinedweb | 285 | 58.35 |
original in it: Leonardo Giordani
it to en: Leonardo Giordani
Student at the Faculty of Telecommunication Engineering in Politecnico of Milan, works as network administrator and is interested in programming (mostly in Assembly and C/C++). Since 1999 works almost only with Linux/Unix.
In order to interlace programs a remarkable complication of the operating system is necessary; in order to avoid conflicts between running programs an unavoidable choice is to encapsulate each of them with all the information needed for their execution.
Before we explore what happens in our Linux box, let's give some technical nomenclature: given a running PROGRAM, at a given time the CODE is the set of instructions which it's made of, the MEMORY SPACE is the part of machine memory taken up by its data and the PROCESSOR STATUS is the value of the microprocessor's parameters, such as the flags or the Program Counter (the address of the next instruction to be executed).
We define the term RUNNING PROGRAM as a number of objects made of CODE, MEMORY SPACE and PROCESSOR STATUS. If at a certain time during the operation of the machine we will save this informations and replace them with the same set of information taken from another running program, the flow of the latter will continue from the point at which it was stopped: doing this once with the first program and once with the second provides for the interlacing we described before. The term PROCESS (or TASK) is used to describe such a running program.
Let's explain what was happening to the workstation we spoke about in the introduction: at each moment only a task is in execution (there is only a microprocessor and it cannot do two things at the same time), and the machine executes part of its code; after a certain amount of time named QUANTUM the running process is suspended, its informations are saved and replaced by those of another waiting process, whose code will be executed for a quantum of time, and so on. This is what we call multitasking.
As stated before the introduction of multitasking causes a set of problems, most of which are not trivial, such as the waiting processes queues management (SCHEDULING); nevertheless they have to do with the architecture of each operating system: perhaps this will be the main topic of a further article, maybe introducing some parts of the Linux kernel code.
Let's discover something about the processes running on our machine. The command which gives us such informations is ps(1) which is an acronym for "process status". Opening a normal text shell and typing the ps command we will obtain an output such as
PID TTY TIME CMD 2241 ttyp4 00:00:00 bash 2346 ttyp4 00:00:00 ps
I state in before that this list is not complete, but let's concentrate on this for the moment: ps has given us the list of each process running on the current terminal. We recognize in the last column the name by which the process is started (such as "mozilla" for Mozilla Web Browser and "gcc" for the GNU Compiler Collection). Obviously "ps" appears in the list becouse it was running when the list of running processes was printed. The other listed process is the Bourne Again Shell, the shell running on my terminals.
Let's leave out (for the moment) the information about TIME and TTY and let's look at PID, the Process IDentifier. The pid is a unique positive number (not zero) which is assigned to each running process; once the process has been terminated the pid can be reused, but we are guaranteed that during the execution of a process its pid remains the same. All this implies is that the output each of you will obtain from the ps command will probably be different from that in the example above. To test that I am saying the truth, let's open another shell without closing the first one and type the ps command: this time the output gives the same list of processes but with different pid numbers, testifying that they are two different processes even if the program is the same.
We can also obtain a list of all processes running on our Linux box: the ps command man page says that the switch -e means "select all processes". Let's type "ps -e" in a terminal and ps will print out a long list formatted as seen above. In order to confortably analyze this list we can redirect the output of ps in the ps.log file:
ps -e > ps.log
Now we can read this file editing it with our preferred editor (or simply with the less command); as stated at the beginning of this article the number of running processes is higher than we would expect. We actually note that list contains not only processes started by us (throught the command line or our graphical environment) but also a set of processes, some of which with strange names: the number and the identity of the listed processes depends on the configuration of your system, but there are some common things. First of all, no matter what type of configuration you gave to the system, the process with pid equal to 1 is always "init", the father of all the processes; it owns the pid number 1 because it is always the first process executed by the operating system. Another thing we can easily note is the presence of many processes, whose name ends with a "d": they are the so called "daemons" and are some of the most important processes of the system. We will study in detail init and the daemons in a further article.
We understand now the concept of process and how important it is for our operating system: we will go on and begin to write mutitasking code; from the trivial simultaneous execution of processes we will shift towards a new problem: the communication between concurrent processes and their synchronization; we will discover two elegant solutions to this problem, messages and semaphores, but the latters will be deeply explained in a further article about the threads. After the messages it will be the time to begin writing our application based on all these concepts.
The standard C library (libc, implemented in Linux with the glibc) uses the Unix System V multitasking facilities; the Unix System V (from now on SysV) is a commercial Unix implementation, is the founder of one of the two most important families of Unix, the other being BSD Unix.
In the libc the pid_t type is defined as an integer capable of containing a pid. From now on we will use it to bear the value of a pid, but only for clarity's sake: using an integer is the same thing.
Let's discover the function which give us the knowledge of the pid of the process containing our program.
pid_t getpid (void)
(which is defined with pid_t in unistd.h and sys/types.h) and write a program whose aim is to print on the standard output its pid. With an editor of your choice write the following code
#include <unistd.h> #include <sys/types.h> #include <stdio.h> int main() { pid_t pid; pid = getpid(); printf("The pid assigned to the process is %d\n", pid); return 0; }Save the program as print_pid.c and compile it
gcc -Wall -o print_pid print_pid.cthis will build an executable named print_pid. I remind you that if the current directory is not in the path it is necessary to run the program as "./print_pid". Executing the program we will have no great surprises: it prints out a positive number and, if executed more than once, you see that this number will increase one by one; this is not mandatory, because another process can be created from a program between an execution of print_pid and the following. Try, for example, to execute ps between two executions of print_pid...
Now it's time to learn how to create a process, but I have to spend some more words about what really happens during this action. When a program (contained in the process A) creates another process (B) the two are identical, that is they have the same code, the memory full of the same data (not the same memory) and the same processor status. From this point on the two can execute in two different ways, for example depending on the user's input or some random data. The process A is the "father process" while the B is the "son process"; now we can better understand the name "father of all the processes" given to init. The function which creates a new process is
pid_t fork(void)and its name comes from the property of forking the execution of the process. The number returned is a pid, but deserves a particular attention. We said that the present process duplicates itself in a father and a son, which will execute interlacing themselves with the other running processes, doing different works; but immediately after the duplication which process will be executed, the father or the son? Well, the answer is simply: one of the two. The decision of which process has to be executed is taken by a part of the operating system called scheduler, and it pays no attention if a process is the father or the son, following an algorithm based on other parameters.
Anyway, it is important knowing what process is in execution, because the code is the same. Both processes will contain the father's code and the son's one, but each of them has to execute only one of this codes. In order to clarify this concept let's look at the following algorithm:
- FORK - IF YOU ARE THE SON EXECUTE (...) - IF YOU ARE THE FATHER EXECUTE (...)which represents in a sort of meta language the code of our program. Let's unveil the mistery: the fork function returns '0' to the son process and the son's pid to the father. So it is sufficient to test if the returned pid is zero and we will know what process is executing that code. Putting it in C language we obtain
int main() { pid_t pid; pid = fork(); if (pid == 0) { CODE OF THE SON PROCESS } CODE OF THE FATHER PROCESS }It's time to write the first real example of multitasking code: you can save it in a fork_demo.c file and compile it as done before. I put line numbers only for clarity. The program will fork itself and both the father and the son will write something on the screen; the final output will be the intelacing of the two output (if all goes right).
(01) #include <unistd.h> (02) #include <sys/types.h> (03) #include <stdio.h> (04) int main() (05) { (05) pid_t pid; (06) int i; (07) pid = fork(); (08) if (pid == 0){ (09) for (i = 0; i < 8; i++){ (10) printf("-SON-\n"); (11) } (12) return(0); (13) } (14) for (i = 0; i < 8; i++){ (15) printf("+FATHER+\n"); (16) } (17) return(0); (18) }
Lines number (01)-(03) contain the includes for the necessary
libraries (standard I/O, multitasking).
The main (as always in GNU), returns an integer, which normally is zero if the program reached the end without errors or an error code if something goes wrong; let's state this time all will run without errors (we will add error control when the basic concepts will be clear). Then we define the data type containing a pid (05) and an integer working as counter for loops (06). These two types, as stated before, are identical, but they are here for clarity's sake.
At line (07) we call the fork function which will return zero to the program executed in the son process and the pid of the son process to the father; the test is at line (08). Now the code at lines (09)-(13) will be executed in the son process, while the rest (14)-(16) will be executed in the father.
The two parts simply write 8 times on the standard output the word "-SON-" or "+FATHER+", depending on which process executes it, and then ends up returning 0. This is really important, because without this last "return" the son process, once the loop has ended, would go further executing the father's code (try it, it does not harm your machine, simply it does not do what we want). Such an error will be really difficult to find, since the execution of a multitasking program (especially a complex one) gives different results at each execution, making debugging based on results simply impossible.
Executing the program you will perhaps be unsatisfied: I cannot assure you that the result will be a real mix between the two strings, and this due to the speed of execution of such a short loop. Probably your output will be a succession of "+FATHER+" strings followed by a "-SON-" one or the contrary. Try however to execute more than once the program and the result may change.
Inserting a random delay before every printf call, we may obtain a more visual multitasking effect: we do this with the sleep and the rand function.
sleep(rand()%4)this makes the program sleep for a random number of seconds between 0 and 3 (% returns the remainder of the integer division). Now the code looks as
(09) for (i = 0; i < 8; i++){ (->) sleep (rand()%4); (10) printf("-FIGLIO-\n"); (11) }and the same for the father's code. Save it as fork_demo2.c, compile and execute it. It is slower now, but we notice a difference in the output order:
[leo@mobile ipc2]$ ./fork_demo2 -SON- +FATHER+ +FATHER+ -SON- -SON- +FATHER+ +FATHER+ -SON- -FIGLIO- +FATHER+ +FATHER+ -SON- -SON- -SON- +FATHER+ +FATHER+ [leo@mobile ipc2]$
Now let us look at the problems we have to face now: we can create a certain number of son processes given a father process, so that they execute operations different from those executed by the father process himself in a concurrent processing environment; often the father needs to communicate with sons or at least to synchronize with them, in order to execute operations at the right time. A first way to obtain such a synchronization between processes is the wait function
pid_t waitpid (pid_t PID, int *STATUS_PTR, int OPTIONS)where PID is the PID of the process whose end we are waiting for, STATUS_PTR a pointer to an integer which will contain the status of the son process (NULL if the information is not needed) and OPTIONS a set of options we have not to care about for now. This is an example of a program in which the father creates a son process and waits until it ends
#include <unistd.h> #include <sys/types.h> #include <stdio.h> int main() { pid_t pid; int i; pid = fork(); if (pid == 0){ for (i = 0; i < 14; i++){ sleep (rand()%4); printf("-SON-\n"); } return 0; } sleep (rand()%4); printf("+FATHER+ Waiting for son's termination...\n"); waitpid (pid, NULL, 0); printf("+FATHER+ ...ended\n"); return 0; }The sleep function in the father's code has been inserted to differentiate executions. Let's save the code as fork_demo3.c, compile it and execute it. We just wrote our first multitasking synchronized application!
In the next article we'll learn more about synchronization and communication between processes; now write your programs using described functions and send me them so that I can use some of them to show good solutions or bad errors. Send me both the .c file with the commented code and a little text file with a description of the program, your name and your e-mail address. Good work! | http://www.linuxfocus.org/English/November2002/article272.meta.shtml | CC-MAIN-2015-22 | refinedweb | 2,643 | 54.56 |
WPA algorithm is very secure, and to get the password usually we have only one way – to brute force it, which could take huge time if password is strong enough. But what if instead of using regular CPUs we would use a power of GPU? Amazon says, that we can use up to 1,536 CUDA cores on g2.2xlarge instance, which costs $0.65 per Hour. Sounds very promising, so let’s see how it can help us to speed up password brute force.
Below I will give step-by-step tutorial on how to deploy Amazon GPU instance and run pyrit (python tool) to crack password using GPU. In this article I assume that you are already familiar with aircrack-ng wi-fi cracking tools. And you’ve already captured handshake into .cap file.
Cracking WiFi Password with Pyrit and NVIDIA GPU on Amazon AWS
Go to Amazon EC2 panel and click Launch new instance
Select Ubuntu Server 14.04 LTS (HVM) 64 bit > GPU instances g2.2xlarge > Review and launch
SSH to your new instance
ssh -i your_aws_key.pem [email protected] cat /etc/lsb-release > DISTRIB_DESCRIPTION="Ubuntu 14.04.3 LTS"
Now, Go to Nvidia website and download latest CUDA installer (choose runfile for Ubuntu 14.04). At the time of writing it is cuda_7.5.18
wget
Install build tools
sudo aptitude update sudo aptitude install build-essential
To avoid ERROR: Unable to load the kernel module ‘nvidia.ko’, install also
sudo aptitude install linux-image-extra-virtual
To avoid ERROR: The Nouveau kernel driver is currently in use by your system.
echo -e 'blacklist nouveau\noptions nouveau modeset=0'| sudo tee /etc/modprobe.d/blacklist-nouveau.conf sudo update-initramfs -u
To avoid ERROR: Unable to find the kernel source tree for the currently running kernel:
sudo aptitude install linux-source sudo aptitude install linux-headers-$(uname -r)
Reboot Now!
sudo shutdown -r now
Extract Nvidia installers
chmod +x cuda_7.5.18_linux.run mkdir ~/nvidia ./cuda_7.5.18_linux.run --extract=~/nvidia/
Run driver installation
sudo ./nvidia/NVIDIA-Linux-x86_64-352.39.run
Download and unzip pyrit and cpyrit-cuda:
wget wget tar -xvzf pyrit-0.4.0.tar.gz tar -xvzf cpyrit-cuda-0.4.0.tar.gz
Install additional libs
sudo apt-get install python-dev libssl-dev libpcap-dev scapy
Install pyrit and cpyrit-cuda
cd ~/pyrit-0.4.0 sudo python setup.py install cd ~/cpyrit-cuda-0.4.0 sudo python setup.py install
Run pyrit list_cores and make sure CUDA cores are detected
pyrit list_cores The following cores seem available... #1: 'CUDA-Device #1 'GRID K520'' #2: 'CPU-Core (SSE2)' #3: 'CPU-Core (SSE2)' #4: 'CPU-Core (SSE2)' #5: 'CPU-Core (SSE2)' #6: 'CPU-Core (SSE2)' #7: 'CPU-Core (SSE2)' #8: 'CPU-Core (SSE2)'
Create file gen_pw.py, modify chars variable which is our characters dictionary. In my case I’m cracking password containing only digits.
import itertools, string, sys def generator_all(charset, min_len, max_len): return (''.join(candidate) for candidate in itertools.chain.from_iterable(itertools.product(charset, repeat=i) for i in range(min_len, max_len + 1))) chars = string.digits #string.ascii_lowercase + string.digits min_chars = int(sys.argv[1]) max_chars = int(sys.argv[2]) gen = generator_all(chars, min_chars, max_chars) for pw in gen: print pw
Run brute force to crack password from 8 to 12 characters length
python gen_pw.py 8 12| pyrit -r xxx.cap -b XX:XX:XX:XX:XX:XX -i - attack_passthrough | https://thehacktoday.com/cracking-wifi-password-with-pyrit-and-nvidia-gpu-on-amazon-aws/ | CC-MAIN-2020-50 | refinedweb | 574 | 59.7 |
Re: PHP Session in new window
From: Axrock (axrock_at_wazzup.co.nz)
Date: 01/23/05
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- In reply to: Harrie Verveer: "Re: PHP Session in new window"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
Date: Mon, 24 Jan 2005 09:23:41 +1300
Hi,
I figured it out, and wanted to post a response in case anybody else has
this problem.
In the form that submits to the popup window, I passed through the session
id.
EG: Create a hidden field in my form with the session ID
<input type='hidden' name='PHPSESSID' value='<?= PHPSESSID ?>' ?>
When returning from the popup back to the original URL I set the PHPSESSID
back to the above.
It will re-enstate the sessions from that ID.
It works perfectly.
Ax
"Harrie Verveer" <newsgroup{remove-this}@harrieverveer.com> wrote in message
news:W7qdnQp6N47RCHrcRVnysA@zeelandnet.nl...
> Hi axrock,
>
> I think you can't do things with the session because you are switching
> between https and http... Do you really need the entire session from the
> popup window or just succes or not? You could try some javascript like
> this:
>
> <script language="JavaScript">
> window.opener.location = "success.php";
> </script>
>
> when you really want the session vars you could do this by get-vars:
>
> <?
> $passGetVars = array();
> foreach ($_SESSION as $key => $val)
> $passGetVars[] = $key . "=" . $val;
>
> $passGetVarsStr = "?" . implode("&",$passGetVars);
> ?>
>
> <script language="JavaScript">
> window.opener.location = "success.php<?=passGetVarsStr?>";
> </script>
>
> something like that... untested but should work - however, I don't think
> it's possible to just use the same session in the opener window and the
> popup window (because of the cross-protocol). this sollution isn't the
> most pretty solution in the world, but it should work...
>
> Harrie
>
> Axrock wrote:
>> Hi,
>>
>> I really need some help here.
>>
>> I have a shopping cart where all cart contents are stored in a session
>> array. At the checkout stage, a new window is opened on a secure URL for
>> entering credit card details. This is a new window (JavaScript popup)
>> because the payment section is actually part of the bank. They have a
>> payment gateway. I am able to pass variables to this which will be
>> returned.
>>
>> Problem is on return (successful transaction etc) I cannot access the
>> session variables in the parent browser window.
>>
>> Can I some how force the popup window (with some PHP code in the return
>> page) to pickup that session so I can access the session variables from
>> the parent window and update them based on my transaction result?
>>
>> I can and have the ability to pass the session id into the popup which
>> will be returned when the transaction is completed via the banks
>> automated system.
>>
>> If somebody can help me out in this area, I would really appreciate it.
>>
>> C.
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{- - ``Control/Monad/Loops/STM'' - (c) 2008 Cook, J. MR SSD, Inc. -} module Control.Monad.Loops.STM where import Control.Concurrent import Control.Concurrent.STM import Control.Monad (forever) -- for the benefit of haddock -- |'Control.Monad.forever' and 'Control.Concurrent.STM.atomically' rolled -- into one. atomLoop :: STM a -> IO () atomLoop x = atomically x >> atomLoop x -- |'atomLoop' with a 'forkIO' forkAtomLoop :: STM a -> IO ThreadId forkAtomLoop = forkIO . atomLoop -- |'Control.Concurrent.STM.retry' until the given condition is true of -- the given value. Then return the value that satisfied the condition. waitFor :: (a -> Bool) -> STM a -> STM a waitFor p events = do event <- events if p event then return event else retry -- |'Control.Concurrent.STM.retry' until the given value is True. waitForTrue :: STM Bool -> STM () waitForTrue p = waitFor id p >> return () -- |'waitFor' a value satisfying a condition to come out of a -- 'Control.Concurrent.STM.TChan', reading and discarding everything else. -- Returns the winner. waitForEvent :: (a -> Bool) -> TChan a -> STM a waitForEvent p events = waitFor p (readTChan events) | http://hackage.haskell.org/package/monad-loops-0.3.0.1/docs/src/Control-Monad-Loops-STM.html | CC-MAIN-2017-30 | refinedweb | 166 | 54.49 |
Overview of firmware-assisted dump
Firmware-assisted dump offers improved reliability over the traditional dump type, by rebooting the partition and using a new kernel to dump data from the previous kernel crash.
Firmware-assisted dump requires:
- An IBM POWER6 processor-based or later hardware platform.
- A logical partition (LPAR) with a minimum of 1.5 GB memory.
- A dump logical volume in the root volume group (rootvg).
- Paging space, which cannot be defined as the dump logical volume
When a partition configured for firmware-assisted dump is started, a portion of memory known as the scratch area is allocated to be used by the firmware-assisted dump functionality. For this reason, a partition that is configured to use the traditional system dump requires a restart to allocate the scratch area memory that is required for a firmware-assisted dump to be initiated. The firm-ware helps in preserving the pages to dump until a non-faulting OS comes up. The non-faulting OS will complete the processing of copying the preserved memory to dump file.
Error codes for firmware-assisted dump
Boot loader will start writing the data in dump logical blocks, and space will be freed as soon as the data in the dump logical blocks is written to the dump logical volume. If a certain percentage of the main memory is freed, then AIX will be allowed to boot. From then on, AIX will take over the control to write the rest of the data in dump logical blocks in to the dump logical volume.
During this process, the boot loader and AIX will notify the progress of firmware-assisted dump to the console.
Following is the light-emitting diode (LED) code used for firmware-assisted dump:
0c0 – Indicates that the firmware-assisted dump is successful
sysdumpdev -l – Is used to check the actual error code from the OS.
Live dump
A live dump capability is provided to allow failure data to be dumped without taking down the entire system. The two most frequent uses of live dumps might include the following scenarios:
- From the command line, a system administrator issues the
livedumpstartcommand to dump data related to the failure.
- From recovery, a subsystem needs to dump out data pertaining to the failure before re-covering. This ability is only available to the kernel and kernel extensions.
Serialized dump and unserialized dump
A serialized live dump refers to a dump that causes the system to be frozen or suspended, while data is being dumped. While the system is frozen, the data is copied into kernel-pinned memory. It is written to the file system only after the system is unfrozen. Unserialized dump refers to take the dump without freezing the system.
The system is frozen by stopping every processor except for the dumping processor. The dump data is then captured with the dumping processor at INTMAX, the most-favored interrupt priority. It should be noted that, while the system is frozen, page faults are not allowed.
Synchronous and asynchronous live dump
In synchronous live dump, the caller waits for the data collection for this dump to complete whereas, in asynchronous live dump, the caller schedules the dump to be taken, but does not wait for completion.
Dump location
The data captured during a live dump pass is queued to the live dump process. When the system is unfrozen, this process then writes the data to the file system. By default, live dumps are placed in the /var/adm/ras/livedump directory. The dump file name has the form: [prefix.]component.yyyymmddhhmm.xx.DZ.
Live dump heap memory
The pinned kernel memory used for live dumps is in a separate live dump heap. By default, this heap is at most 64 MB. The heap may not be larger than 1/16 of the size of real memory.
Live dump pass
A serialized live dump may occur in one pass or multiple passes. A dump pass consists of the data that could be buffered in pinned storage while the system was frozen. A dump taken in mul-tiple passes involves multiple system freezes, and thus, the data in a multipass dump may not be consistent. A live dump can be initiated from software by the kernel or a kernel extension. Any component to be included in the dump must have previously registered with the kernel, using
ras_register(), as dump aware. They must also have indicated that they handle live dumps by using the
RASCD_SET_LDMP_ON ras_control() service.
Component memory level and maximum buffer size
The following list shows the data limits for a component. If the component exceeds these limits, its data is truncated by only dumping its data entries prior to the one that caused the limit to exceed.
The following list specifies the maximum data allowed for each live dump detail level
- < CD_LVL_NORMAL - 2 MB
- >= CD_LVL_NORMAL and < CD_LVL_DETAIL - 4 MB
- >= CD_LVL_DETAIL and < CD_LEVEL_9 - 8 MB
- CD_LEVEL_9 - unlimited(real memory/16)
To perform a live dump from software:
- Use
ldmp_setupparms()to initialize an
ldmp_parms_titem.
This sets up the data structure, filling in all default values including the eye catcher and version fields.
- Specify components, using
dmp_compspec(), and pseudo-components.
This is how the content of the dump is specified.
- Create the dump using the
livedump()kernel service.
This takes the dump.
This is shown at the end of the example.
Pseudo component
A dump pseudo-component refers to a service routine used to dump data that is not associated with a component. Such pseudo components (such as kernel context, thread, process, and so on) are provided strictly for use within a dump.
Staging buffer
A component might request for space in a staging buffer for use during a system or live dump. For the system dump, a component may allocate a private (RASCD_SET_SDMP_STAGING) or a shared staging buffer (RASCD_SET_SDMP_SHARED_STAGING). A private staging buffer is necessary if the buffer is to be used for actual data to be dumped (for example, a device's mi-crocode or log). A shared staging buffer might be used if the area is only used for dump metadata such as the component's dump table.
Live dump sequence through callback
A component participating in a live dump must have a callback routine to handle the following
ras_control() commands. Upon receipt of the callback command, the callback issues the
"
_SET" command to perform the action. Refer to the example extension, paying particular attention to the
sample_callback() function.
RASCD_LDMP_PREPARE (used to prepare to take a live dump)
The callback receives this call when it has been asked to participate in a live dump. The callback may use
dmp_compspec() to specify other components to include in the dump if necessary. It may also specify pseudo components such as
dmp_eaddr().It must return an estimate of the amount of data to be dumped. This should be a maximum amount. It should include the space taken up by the dump table. It should not include the memory dumped by other components or pseudo components. If, for example, the prepare function uses
dmp_ct() to dump component trace data, the
dmp_ct() pseudo component will provide that estimate.
RASCD_LDMP_START
(used to dump data)
This is the command received by a callback when it is to provide its data for the dump. The callback puts its dump table address in the
ldmpst_table field of the
ldmp_start_t data item received as the argument. The callback receives subsequent
RASCD_LDMP_AGAIN calls to provide more data. This stops when the callback returns a
NULL dump table pointer.
RASCD_LDMP_FINISHED
-
This is the command indicating that the dump is finished. Also, no data is dumped for that component.
RASCD_LDMP_AGAIN
-
The
RASCD_LDMP_AGAIN command provides more data. The return code is treated the same as for RASCD_LDMP_START, except that if a value less than zero is returned, no further data is dumped for the component, but data already dumped by previous
RASCD_LDMP_START and
RASCD_LDMP_AGAIN calls will appear in the dump.
RASCD_LDMP_FINISHED
-
This command indicates that the live dump is complete.
RASCD_DMP_PASS_THROUGH
- This command just passes arbitrary text data to the callback.
Note that
RASCD_DMP_PASS_THROUGH applies to the entire dump domain, (that is) there is only one pass through for the domain containing live and system dump. You can pass data to a component’s
RASCD_DMP_PASS_THROUGH handler by using dumpctrl.
For example, the command,
dumpctrl -l foo "pass through text" passes
"pass through text" to the
RASCD_DMP_PASS_THROUGH handler for the component with alias of
foo.
RASCD_LDMP_ESTIMATE
-
This command provides an estimate of how much data would be dumped.
There are some constraints placed on live dumps:
- A component is limited in what it can dump by the detail level.
- As the live dump can happen while the system is frozen, only a limited set of system services may be used by the component callbacks during the dump, for example, lightweight memory trace and component trace.
A component may specify any data to be dumped, however, in a serialized dump, only memory resident data is dumped.
Consideration for live dump data requirements
Multiple passes
It is provided to a component that is required to dump more data and that can not be dumped in a single freeze. It can be dumped in multiple passes through staging buffer, but data might be changed in unfreeze and next freeze time. Single passes allowed for a component if it is a serialized dump taken from an interrupted environment. It can be implemented through
RASCD_LDMP_AGAIN callback in the component.
Freeze time
If, while performing a live dump, the system is frozen for more than 100 milliseconds (0.1 seconds) an informational error is logged. It is important to keep dump callback execution paths as short as possible, especially when providing data for the dump. If we detect that the system has been frozen for 5000 milliseconds, that is 5 seconds, the dump is truncated at that point, and the system is unfrozen.
Heap allocation errors
There might be cases when a component can be tried to take dump more than the allowed limit with respect to the level. So it is the component’s responsibility to increase the private staging buffer and use multiple passes to dump more data from the component (not possible for driver running in an interrupted environment).
Example
This shows a sample kernel extension that will take a live and system dump. The important function is
sample_callback(), which takes a dump using the
ras_control() commands sent by the system. Note that I have only shown the handling of the dump commands. Normally, this callback would handle component trace and error checking commands as well.
Following the sample extension is a brief sequence of statements used to take a live dump of
sample_comp from software.
#include <sys/types.h> #include <sys/syspest.h> #include <sys/uio.h> #include <sys/processor.h> #include <sys/systemcfg.h> #include <sys/malloc.h> #include <sys/ras.h> #include <sys/livedump.h> #include <sys/eyec.h> #include <sys/raschk.h> #include <sys/param.h> #include <sys/dump.h> /* RAS conmtrol block for the component */ ras_block_t rascb=NULL; /* Data to include in livedump */ typedef struct sample_data { char *dev; int flag; } sample_data_t; sample_data_t *data; /* componet callback */ kerrno_t sample_livedump_callback(ras_block_t cb, ras_cmd_t cmd, void *arg, void *priv); void sample_initiate_livedump(); /* * Entry point called when this kernel extension is loaded. * * Input: * cmd - 1=config, 2=unconfig) * uiop - points to the uio structure. */ int sampleext(int cmd, struct uio *uiop) { kerrno_t rv = 0; int rc,len; char *comp="/dev/sample"; /* cmd should be 1 or 2 */ if (cmd == 2) { /* Unloading */ if (rascb) ras_unregister(rascb); xmfree(data, kernel_heap); return(0); } if (cmd != 1) return(EINVAL); /* Allocate data */ data = xmalloc(sizeof(sample_data_t), 1, kernel_heap); if (!data) { return(ENOMEM); } len = strlen(comp)+1; data->dev=xmalloc(len, 1, kernel_heap); strcpy(data->dev,comp); data->flag = 0; /* Register the component as dump aware */ rv = ras_register(&rascb, "sample_livedump", (ras_block_t)0, RAS_TYPE_FILESYSTEM , "sample component", RASF_DUMP_AWARE, sample_livedump_callback, NULL); if (rv) return(KERROR2ERRNO(rv)); /* turn on component live dump */ rv = ras_control(rascb, RASCD_SET_LDMP_ON, 0, 0); if (rv) return(KERROR2ERRNO(rv)); /* dump staging buffer space must be set up to store the dump table */ rv = ras_control(rascb, RASCD_SET_SDMP_STAGING, (void*)(sizeof(struct cdt_nn_head)+ sizeof(struct cdt_entry)), 0); if (rv) return(KERROR2ERRNO(rv)); /* To make persistent */ rv = ras_customize(rascb); if (rv) return(KERROR2ERRNO(rv)); sample_initiate_livedump(); return(0); } /* * Sample Callback that is called for live dump. * * The data to dump consists of a header and data . * * Input: * cb - Contains the component's ras_block_t. * cmd - ras_control command * arg - command argument * priv - private data, unused. */ kerrno_t sample_livedump_callback(ras_block_t cb, ras_cmd_t cmd, void *arg, void *priv) { kerrno_t rv = 0; switch(cmd) { case RASCD_LDMP_ON: { /* Turn live dump on. */ rv = ras_control(cb, RASCD_SET_LDMP_ON, 0, 0); break; } case RASCD_LDMP_OFF: { /* Turn live dump off. */ rv = ras_control(cb, RASCD_SET_LDMP_OFF, 0, 0); break; } case RASCD_LDMP_LVL: { /* Set livedump data level */ rv = ras_control(cb, RASCD_SET_LDMP_LVL, arg, 0); break; } case RASCD_LDMP_ESTIMATE: /* fall through */ case RASCD_LDMP_PREPARE:{ /* * The prepare call is used to request staging buffer space * and provide an estimate of the amount of data to be dumped */ ldmp_prepare_t *p = (ldmp_prepare_t*)arg; int n = 0; /* Staging buffer used for dump table */ p->ldpr_sbufsz =sizeof(struct cdt_nn_head)+ sizeof(struct cdt_entry) ; p->ldpr_datasize = p->ldpr_sbufsz + sizeof(sample_data_t); break; } case RASCD_LDMP_START: { /* * This is received to provide the dump table. * the table is an limited table here. */ ldmp_start_t *p = (ldmp_start_t*)arg; struct cdt_nn_head *hp; struct cdt_entry *ep; hp = (struct cdt_nn_head*)p->ldmpst_buffer; bzero(hp,sizeof(struct cdt_nn_head)); hp->cdtn_magic = DMP_MAGIC_N; hp->cdtn_len=sizeof(struct cdt_nn_head)+ sizeof(struct cdt_entry); ep = (struct cdt_entry*)(hp+1); strcpy(ep->d_name, "dev1"); ep->d_len = sizeof(sample_data_t); ep->d_ptr = &data; ep->d_segval = DUMP_GEN_SEGVAL; p->ldmpst_table = hp; break; } case RASCD_LDMP_AGAIN: break; case RASCD_LDMP_FINISHED: break; case RASCD_DMP_PASS_THROUGH:{ /* pass through */ printf("%s\n", arg); break; } default: { printf("bad ras_control command.\n"); rv = EINVAL_RAS_CONTROL_BADCMD; } } return(rv); } void sample_initiate_livedump() { ldmp_parms_t sample_params; kerrno_t kc,rc; if(ldmp_setupparms(&sample_params)==0) { sample_params.ldp_title= "sample"; sample_params.ldp_errcode = 3; sample_params.ldp_symptom = "sam";; sample_params.ldp_func = "func";; if (dmp_compspec(DCF_FAILING|DCF_BYCB, rascb, &sample_params, NULL, NULL)) { printf("Error"); } rc=livedump(&sample_params); if(rc!=0) { printf("Error %d",rc); } } else { printf("Error"); } }
To include sample_comp in a live dump initiated from the command line, run the following command:
livedumpstart -C sample_comp symptom="sample dump"
Resources
1. Livedump kernel service
3. Firmware assisted dump – progress codes. | http://www.ibm.com/developerworks/aix/library/au-aix-ras-firmware/index.html | CC-MAIN-2016-18 | refinedweb | 2,361 | 54.22 |
Today!
Hi Jason,
Congratulation on the new job.
If I could ask for one thing to be added to vsNext it would be a difficult one to create but essential in the post-multi-core development environment of the future – that is some kind of decent multi-threaded debugging experience. It would also have to work in something like an Ajax development environment as well.
I’m not sure how you’d do it – but I’d be very grateful if your team found a way…
Andrew
Hi Jason,
Good luck in your new job.
One thing I would like to see support for in VS is merging of solution-files. Another neat feature is something Borland (now CodeGear) has in their Delphi and C# Builder IDE: history of local changes. This means that you can track the changes done to a file locally (without checking the file in to source control) with compare.
Regards,
Trygve
thanks for the suggestions!
Andrew – We are indeed working on several things related to more cores, stay tuned…
Trygve – these sound like useful changes in the editor, I’ll pass them along
Jason
Hey, Jason. Congratulations!
A few wishes:
* Keep adding static analysis features, even on-the-fly hints.
* Work with the Open Source tools community to avoid incompatibilities or completely killing OS projects.
* I’m still waiting for a full online IDE. With Silverlight and the DLR available, one should be able to code and debug right into the browser. Think Popfly Pro! 😎
Best luck!
Martin Salias
Enterprise Architect
Microsoft South Cone
Good luck with your new role.
I love working with VS and miss it when I work with other languages and IDEs. In my opinion it really is one of the best IDEs available for any environment.
The main change I would like to see is for functionality beyond the core text editing to be implemented as plugins, rather than fixed in the core product. I would like to see lots of small extension components covering functionality such as designers, refactoring, unit test runners, code analysis, profilers, searching, code completion, etc.
Most developers would never notice the change in structure, but for those of us who like to configure our environments with a multitude of extension plugins it would make life much easier for several reasons:
1) It would encourage plugin developers to provide small specialised plugins rather than big tools with multitudes of functionality. I think this happens because they almost feel they are compteting against VS and need to provide lots of stuff to justify spending the money on the plugin.
2) It would enable developers to substitute third party plugins for Microsoft functionality if we desired without having confusing menus showing both sets of options. This happens when you add a plugin but can’t easily turn off the Microsoft functionality.
3) It would create a level playing field for third party tool vendors to compete with Microsoft. I think there would be more plugins available for VS if vendors didn’t fear that Microsoft would just introduce equivalent functionality into the base system. If they knew that any Microsoft equivalent was also a plugin that they could compete directly against they would be happier.
I think the VS 2008 Shell is a great step in the right direction and would love to see a future system where that is the starting point and you can just select from a list of options to configure your environment. There is even a potential revenue stream to include third-party vendor plugins as part of the basic in the box selection pack.
Regards
Ian Chamberlain
thanks Martin & Ian, great feedback!
1. Bookmark window.
Congratulations,
What is happening with FoxPro and will VS be adding ever again.
Congratulations on the new job.
I would like to see VS always provide the ability to convert from the previous release to the new release without making any manual changes. This would make it easier as well as encourage enterprises to stay current with their application systems. I am not saying to support older versions but at least make it so they can open the solutions in the next version and successfully build and deploy them.
Thanks, Clyde
I would love to see Visual Studio ported to Linux operating system. Do you have any plans on bring any version of Visual Studio to other operation system?
Regards,
Justin
A couple of things I’d like to see in VS:
(1) A ribbon-like Toolbox. The present Toolbox is hard to find stuff in, particularly if you 3rd party controls.
(2) This is more on the lines of design philosophy. There are two types of development; systems development and applications development. Systems developers are concerned with the nitty-gritty of developing controls, compilers and such. Applications developers are concerned with producing solutions for line of business applications. The VB and C# are too labor intensive for RAD development. For instance there are literally hundreds, maybe thousands, of choices in the namespaces, intellisence syntax. Auto-selection of style design (look and feel), auto-generation of standard app scenarios (eg starter kits) and Acropolis are steps in the right direction. But the basic point is design of programming tools should diverge into two camps; systems and applications. And no, Access and Foxtrot do not do it.
And (3) while I am on my high-horse the present state of documentation is simply terrible. Everything under the sun is crammed together onto MSDN DVDs. Try to look up a simple syntax question for VS 2005. It simply sucks. Documentation for each new release should come on its own CD and knowledge base should be kept separate.
Onward and upward! -BG
Hello Jason,
One thing that I would like to have in Visual Studio is the ability to attach documents that describe within the code editor, similar to how you can embed images, tables, and visio diagrams within MS Word. Just the other day I had a complex non-UML diagram that I wanted to appear when someone opened the code.
For now I have been placing the files as part of the project. Good luck!
Regards,
Fritz
Hi Jason,
3 Very usefull features would be:
– A Decent Line Counting Tool inside the IDE
– The ability to extract an XML Help File from a web site (without having to convert it to a web application)
– At the moment you can customize the colors of your editor and some other windows. It would be really great if you could skin or color all the windows and toolbars in VS to give a complete look.
More memmory leaking analyzer in the c++ module.
Hi Jason,
one of my biggest wishes for the Orcas+1 release is support for C++0x. It would be great if Visual Studio were one of the early adopters of the updated C++ spec.
VC++ devs had a very bad experience when it took until VS2003 (FIVE years after formal standardization!) to get a reasonably conforming compiler. This should never ever happen again.
Best regards
Take a look at the Eclipse IDE. If VS will do what Eclipe does in terms of code editing and refactory, you can call it an IDE.
New lead for the Visual Studio team
Hi,
Congrats for joining this team.
We are expecting much in IronRuby support.
We are looking for a special IDE for DLR. just the way VS2008 works today for Vb and C#.
The tool IDE can be given a name such as DLR Express, which comes strictly for DLR languages, such as IronRuby, IronPython, IronLisp, VB Dynamic etc..
It would be great if you could study few great IDE like (1) Komodo (2) 3rdrail (3) NetBeans (4)E-text etc.
The popularity for DLR languages is totally dependent on Great IDE specially built for them.
MS and Your Team should take a serious note of this and perhaps create a poll or feedback to know more reviews.
Thanks
IronRuby
Hi Jason
Congrats with the new job
I would like to have the opertunity to change colour and Font in all windows.
Finn
Jason,
Congrats! I hope you enjoy. I am a big fan of VS and TFS/Team Suite. Are you going to be working in the TFS area as well or is that a different group? If TFS is part of your domain, please consider better Outlook to TFS integration between Tasks and Work Items. Also, OneNote integration would be nice as well.
Thanks,
David
Hi Jason,
Congrats for new great job!!
One major thing, which i would like to have in .net is transforming of ASP.NET Application to Windows based and vice versa.
This would be fantastic if we have this feature available in Next Big Version.
Hope your team work on it.
Thanks,
Amrat Nandlal
Hi,
Congratulation on the new job.
A couple of things I’d like to see in VS:
1. The auto-generated code uses the "int" keyword instead of "Int32", or "bool" instead of "Boolean"… It’d be amazing, however, if the programmer could specify which pattern the auto-generated code engine should follow.
2. When renaming a formal parameter of a method in C#, the comments of the mentioned method (if any) should reflect the changes too.
Good luck,
Mehdi Mousavi [ ]
thanks everyone for the great feedback. I see a few themes:
* Increased extensibility in the IDE. We are working on this, including introducing ways to write new VSIP plug-ins using managed code.
* Navigation, discoverability, and productivity increases (fonts, windows, toolbox, etc)
* Questions around platform coverage.
– We have not planned changes around FoxPro
– We’re not planning to take VS off Windows. However we did add cross debugging support for the Mac for Silverlight 1.1.
* Better tools for systems developers (threading, code focused, etc)
* DLR specific questions. I’ve been building dynamic langauges support in the CLR for quite a while so I have a lot of passion around this one as well.
Thanks for all the great feedback! I’m going to use my blog to cover both great new things in VS2008 and when the time is right, the next version for feature feedback.
thanks,
Jason
I recently switched from managing a large group (VB, VC#, VC++, and Phoenix product units) to working | https://blogs.msdn.microsoft.com/jasonz/2007/09/15/new-job-new-challenges/ | CC-MAIN-2016-30 | refinedweb | 1,718 | 63.19 |
04 December 2008 16:11 [Source: ICIS news]
(recasts lead and adds detail throughout)
LONDON (ICIS news)--Shell's Pernis refinery is still online despite the fire that broke out in a pipeline, a spokesman for the Anglo-Dutch oil major confirmed on Thursday.
The fire, which broke out at approximately 13:20 local time (12:20 GMT), was thought to have been as a result of a pipe leaking heavy fuel oil near one of the 395,000 bbl/day refinery’s catalytic crackers.
Emergency services were quickly alerted and the blaze was brought under control by around 15:00 local time, but not yet fully put out.
“There are about 40 units on the site and all those outside the affected area are still running,” said spokesman Wim van De Wiel. “There were no injuries as a result of the fire, and most of the staff did not need to be evacuated.”
Added Tinet Jonge of the ?xml:namespace>
“The refinery was evacuated. There was a lot of smoke, but luckily it didn’t appear to be chemical smoke.”
The fire follows a troubled few months for the giant refinery. At the end of September, another fault with a site catalytic cracker led to a shutdown that sources reported lasted for a number of weeks.
After other planned maintenance work, the plant was reported to have come back on stream only two weeks | http://www.icis.com/Articles/2008/12/04/9177021/pernis-refinery-still-online-after-fire-shell.html | CC-MAIN-2013-48 | refinedweb | 235 | 67.79 |
Completing the application tests
We’ve now finished the blog engine we wanted to create in this tutorial. However the project itself is not yet completely finished. To be totally confident with our code we need to add more tests to the project.
Of course we’ve already written unit tests in order to test all the yabe model layer functionality. And it’s great as it will ensure that the blog engine’s core functionality is well tested. But a web application is not only about the ‘model’ part. We need to ensure that the web interface works as expected. That means testing the yabe blog engine’s controller layer. But we even need to test the UI itself, as for example, our JavaScript code.
Testing the controller part
Play gives you a way to test directly the application’s controller part using JUnit. We call these tests ‘Functional tests’. This is because we want to test the web application’s complete functionality.
Basically a functional test calls the Play
ActionInvoker directly, simulating an HTTP request. So we give an HTTP method, a URI and HTTP parameters. Play then routes the request, invokes the corresponding action and sends you back the filled response. You can then analyze it to check that the response content is like you expected.
Let’s write a first functional test. Open the
yabe/test/ApplicationTest.java unit test:
import org.junit.*; import play.test.*; import play.mvc.*; import play.mvc.Http.*; import models.*; public class ApplicationTest extends FunctionalTest { @Test public void testThatIndexPageWorks() { Response response = GET("/"); assertIsOk(response); assertContentType("text/html", response); assertCharset("utf-8", response); } }
It looks like a standard JUnit test for now. Note that we use the Play
FunctionalTest super class in order to get all useful utility helpers. This test is correct and just checks that the application home page (typically the
/ URL renders an HTML response with ‘200 OK’ as status code).
Now we will check that the administration area’s security works as expected. Add this new test to the
ApplicationTest.java file:
… @Test public void testAdminSecurity() { Response response = GET("/admin"); assertStatus(302, response); assertHeaderEquals("Location", "/login", response); } …
Now run the yabe application in test mode using the
play test command, open, select the
ApplicationTest.java test case and run it.
Is it green?
Well, we could continue to test all the application functionalities this way, but it’s not the best way to test an HTML-based web application. As our blog engine is intended to be executed in a web browser, it would be better to test it directly in a real web browser. And that’s exactly what Play’s ‘Selenium tests’ do.
These kinds of JUnit based ‘Functional tests’ are still useful, typically to test Web services returning non-HTML responses such as JSON or XML over HTTP.
Writing Selenium tests
Selenium is a testing tool specifically for testing web applications. The cool thing here is that Selenium allows to run the test suite directly in any existing browser. As it does not use any ‘browser simulator’, you can be sure that you’re testing what your users will use.
A Selenium test suite is typically written as an HTML file. The HTML syntax required by Selenium is a little tedious to write (formatted using an HTML table element). The good news is that Play helps you generate it using the Play template engine and a set of tags that support a simplified syntax for Selenium scenarios. An interesting side effect of using templates is that you are not tied to ‘static scenarios’ any more and you can use the power of Play templates (looping, conditional blocks) to write more complicated tests.
However you can still write plain HTML Selenium syntax in the template and forget the specific Selenium tags if needed. It can become interesting if you use one of the several Selenium tools that generates the test scenarios for you, like Selenium IDE.
The default test suite of a newly-created Play application already contains a Selenium test. Open the
yabe/test/Application.test.html file:
*{ You can use plain Selenium commands using the selenium tag }* #{selenium} // Open the home page, and check that no error occurred open('/') waitForPageToLoad(1000) assertNotTitle('Application error') #{/selenium}
This test should run without any problem with the yabe application. It just opens the home page and checks that the page content does not contain the ‘Application error’ text.
However like any complex test, you need to set-up a set of well-known data before navigating the application and testing it. We will of course reuse the fixture concept and the
yabe/test/data.yml file that we’ve used before. To import this data set before the test suite, just use the
#{fixture /} tag:
#{fixture delete:'all', load:'data.yml' /} #{selenium} // Open the home page, and check that no error occurred open('/') waitForPageToLoad(1000) assertNotTitle('Application error') #{/selenium}
Another important thing to check is that we have a fresh user session at the test start. The session being stored in a browser transient cookie, you would keep the same session during two successive test runs.
So let’s start our test with a special command:
#{fixture delete:'all', load:'data.yml' /} #{selenium} clearSession() // Open the home page, and check that no error occurred open('/') waitForPageToLoad(1000) assertNotTitle('Application error') #{/selenium}
Run it to be sure that there is no mistake. It should be green.
So we can write a more specific test. Open the home page and check that the default posts are present:
#{fixture delete:'all', load:'data.yml' /} #{selenium 'Check home page'} clearSession() // Open the home page open('/') // Check that the front post is present assertTextPresent('About the model layer') assertTextPresent('by Bob, 14 Jun 09') assertTextPresent('2 comments , latest by Guest') assertTextPresent('It is the domain-specific representation') // Check older posts assertTextPresent('The MVC application') assertTextPresent('Just a test of YABE') #{/selenium}
We use the standard Selenium syntax, called Selenese.
Run it (you can run in a different window just by opening the test link in a new window).
We will now test the comments form. Just add a new
#{selenium /} tag to the template:
#{selenium 'Test comments'} // Click on 'The MVC application post' clickAndWait('link=The MVC application') assertTextPresent('The MVC application') assertTextPresent('no comments') // Post a new comment type('content', 'Hello') clickAndWait('css=input[type=submit]') // Should get an error assertTextPresent('no comments') assertTextPresent('Author is required') type('author', 'Me') clickAndWait('css=input[type=submit]') // Check assertTextPresent('Thanks for posting Me') assertTextPresent('1 comment') assertTextPresent('Hello') #{/selenium}
And run it. Well it fails; and we have a serious problem here.
We can’t really correctly test the captcha mechanism, so we have to cheat. In test mode we will validate any code as a correct captcha. We know that we’re in test mode when the framework id is
test. So let’s modify the
postComment action in the
yabe/app/controllers/Application.java file to skip this validation in test mode:
… if(!Play.id.equals("test")) { validation.equals(code, Cache.get(randomID)).message("Invalid code. Please type it again"); } …
Now just modify the test case to type any code in the text field, as is:
… type('author', 'Me') type('code', 'XXXXX') clickAndWait('css=input[type=submit]') …
And now run the test again, it should work.
Measuring code coverage
Of course we haven’t written all required test cases for the application. But it’s enough for this tutorial. Now in a real-world project, how can we know if we have written enough test cases? We need something called ‘code coverage’.
The Cobertura module generates code coverage reports using the Cobertura tool. Install the module using the
install command:
play install cobertura-{version}
We need to enable this module only for test mode. So add this line to the
application.conf file, and restart the application in test mode.
# Import the cobertura module in test mode %test.module.cobertura=${play.path}/modules/cobertura
Now reopen the browser at the URL, select all tests and run them. All should be green.
When all tests are passed, stop the application and cobertura will then generate the code coverage report. You can then open the
yabe/test-result/code-coverage/index.html in your browser and check the report.
If you start the application again, you can also view it at.
As you see we’re far from testing all of the application’s cases. A good testing suite should approach 100%, even if it is of course nearly impossible to check all the code. Typically because we often need to hack in test mode, like we did for the captcha.
Next: Preparing for production. | https://www.playframework.com/documentation/1.2.4/guide10 | CC-MAIN-2015-27 | refinedweb | 1,452 | 55.64 |
Natively Unit-Testing ES6 Modules in Browser Including Coverage
by Thomas Urban
Recent versions of most common browsers support ES6 modules natively. Before that transpilers like webpack or babel have been used to convert code to something browsers were capable of processing back then. This includes browser-side unit testing.
In some cases using transpilers might cause side effects on tested code and test implementations. That's why it is time to upgrade your testing to the present. This is a brief tutorial on how to achieve that.
Some Context First
Consider a project folder containing implementation files in sub-folder src/ and unit testing code in test/ with either test implementation file having extension .spec.js. An implementation might look like this file src/core/main.js:
export class MainCore { static someFeature( input ) { return 2 * input; } }
There should be a test implementation in a file like test/core/main.spec.js:
import { MainCore } from "../../src/core/main.js"; describe( "Class MainCore", () => { it( "doubles provided value on using static method someFeature()", () => { MainCore.someFeature( 5 ).should.be.equal( 10 ); } ); } );
This test implementation is meant to rely on mocha for test-running and on shouldjs for assertions. There are different tools for either task but we have decided to stick with a particular set that we deemed to be suitable for all our software.
Setting Up Karma
Karma is a tool for running unit tests in a browser. Mocha is a test runner as well, but it's meant to run on command line using Node.js. It is great for server-side code implemented in Javascript. Karma is another command line tool moving mocha into a browser enabling it to test browser-side features, as well.
Install Karma And Its Plugins
Install karma in your project with
npm i -D karma
In addition you need some plugins:
npm i -D karma-mocha karma-should
These two are used to expose mocha and should in browser (thus you don't need to import them in your test implementations as demonstrated before).
npm i -D karma-chrome-launcher karma-firefox-launcher karma-edge-launcher
These plugins are required for controlling browsers to run your unit tests. There are plugins for all major browsers and you should install launcher for either one you want to test your code with. Consider Edge for local testing, only, as it might be missing in a CI context.
npm i -D karma-coverage-istanbul-instrumenter karma-coverage-istanbul-reporter
Finally, these two are highly recommended for assessing your tests' quality and for identifying that part of your code which hasn't been tested well, yet.
Configure Karma
Karma checks a configuration file named karma.conf.js in root folder of your project. You can have any other file as well and pick it on invoking karma as described below.
Your configuration file should look like this:
const Path = require( "path" ); module.exports = function( config ) { config.set( { frameworks: [ "mocha", "should", ], files: [ // tests { pattern: "test/unit/**/*.spec.js", type: "module" }, // files tests rely on { pattern: "src/**/*.js", type: "module", included: false }, ], reporters: [ "spec", "coverage-istanbul" ], browsers: ["ChromeHeadless"], singleRun: true, preprocessors: { "**/!(*.spec).js": ["karma-coverage-istanbul-instrumenter"] }, coverageIstanbulInstrumenter: { esModules: true }, coverageIstanbulReporter: { reports: [ "html", "text" ], dir: Path.join( __dirname, "coverage" ), }, } ); };
Let's see what this is about:
- First block of configuration named frameworks is listing frameworks used for testing.
- Next block is selecting files to expose for use in browser. Karma is running a web service providing all matching files.
- pattern is a glob pattern selecting files related to this configuration file.
- type is set to module to enable browser's support for ES6 modules on those files.
- included is set false on files that aren't meant to contain test implementation but some actually tested code.
- reporters is listing some reporters used to display results of running unit tests:
- spec is listing run tests and their result.
- coverage-istanbukt is enabling integration of karma-coverage-istanbul-reporter. It is configured separately. Just see below.
- browsers is an array listing browsers to run tests in. For every named browser the related launcher must be installed. Some launchers cover multiple browsers you can use here. E.g. Chrome and ChromeHeadless are both supported by karma-chrome-launcher.
- singleRun is a boolean controlling whether running your tests once, only, or watching your selected files for changes and re-run tests each time either file is changing on disk. You can control this when invoking karma using option --single-run or --no-single-run.
- preprocessors usually integrate transpilers. Code coverage usually is integrated with transpilers. For we don't want transpilers we still need to integrate code coverage tools here. Since we don't care for the coverage of test implementation the given rule is meant to apply to every Javascript file that doesn't use extension .spec.js.
- Final two blocks are given in example for karma-coverage-istanbul-instrumenter. The essential difference here is the selection of enabled coverage reporters: html is used to create a set of HTML files in folder given by option dir showing a summary and either file's source code with missing lines of code highlighted. text is displaying a tabular summary as part of your test runner's output (causing it to appear in console or in CI logs).
Run The Tests
Basically running tests is as simple as invoking
karma run
on command line of your project. You should have a script in your package.json
... "scripts": { "test": "karma run" } ...
This way you can have different configurations using different invocable scripts:
... "scripts": { "test": "karma run", "test:dev": "karma run karma.alt.conf.js --browsers=Firefox,Chrome,Edge" } ...
This example adds another script using different configuration file and adjusting set of browsers to run.
Setting Up CI
We use GitLab for CI and this is a working configuration suitable for running Chrome-based unit tests. Put this code into a file .gitlab-ci.yml in your project's root folder:
image: "cepharum/e2e-chrome-ci" test: stage: test variables: NODE_ENV: development script: - npm install - npm run test artifacts: paths: - coverage name: coverage
This configuration is adding a CI task running your package.json-based script named test. In addition it is picking up HTML-based coverage report from sub-folder coverage/ and expose it as an artifact on pipeline view of GitLab. | https://blog.cepharum.de/en/post/natively-unit-testing-es6-modules-in-browser-including-coverage.html?page_n18=2 | CC-MAIN-2020-24 | refinedweb | 1,055 | 56.45 |
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