| ''' |
| This module provides a newsuper() function in Python 2 that mimics the |
| behaviour of super() in Python 3. It is designed to be used as follows: |
| |
| from __future__ import division, absolute_import, print_function |
| from future.builtins import super |
| |
| And then, for example: |
| |
| class VerboseList(list): |
| def append(self, item): |
| print('Adding an item') |
| super().append(item) # new simpler super() function |
| |
| Importing this module on Python 3 has no effect. |
| |
| This is based on (i.e. almost identical to) Ryan Kelly's magicsuper |
| module here: |
| |
| https://github.com/rfk/magicsuper.git |
| |
| Excerpts from Ryan's docstring: |
| |
| "Of course, you can still explicitly pass in the arguments if you want |
| to do something strange. Sometimes you really do want that, e.g. to |
| skip over some classes in the method resolution order. |
| |
| "How does it work? By inspecting the calling frame to determine the |
| function object being executed and the object on which it's being |
| called, and then walking the object's __mro__ chain to find out where |
| that function was defined. Yuck, but it seems to work..." |
| ''' |
|
|
| from __future__ import absolute_import |
| import sys |
| from types import FunctionType |
|
|
| from future.utils import PY3, PY26 |
|
|
|
|
| _builtin_super = super |
|
|
| _SENTINEL = object() |
|
|
| def newsuper(typ=_SENTINEL, type_or_obj=_SENTINEL, framedepth=1): |
| '''Like builtin super(), but capable of magic. |
| |
| This acts just like the builtin super() function, but if called |
| without any arguments it attempts to infer them at runtime. |
| ''' |
| |
| if typ is _SENTINEL: |
| |
| f = sys._getframe(framedepth) |
|
|
| try: |
| |
| type_or_obj = f.f_locals[f.f_code.co_varnames[0]] |
| except (IndexError, KeyError,): |
| raise RuntimeError('super() used in a function with no args') |
|
|
| try: |
| typ = find_owner(type_or_obj, f.f_code) |
| except (AttributeError, RuntimeError, TypeError): |
| |
| try: |
| typ = find_owner(type_or_obj.__class__, f.f_code) |
| except AttributeError: |
| raise RuntimeError('super() used with an old-style class') |
| except TypeError: |
| raise RuntimeError('super() called outside a method') |
|
|
| |
| if type_or_obj is not _SENTINEL: |
| return _builtin_super(typ, type_or_obj) |
| return _builtin_super(typ) |
|
|
|
|
| def find_owner(cls, code): |
| '''Find the class that owns the currently-executing method. |
| ''' |
| for typ in cls.__mro__: |
| for meth in typ.__dict__.values(): |
| |
| |
| try: |
| while not isinstance(meth,FunctionType): |
| if isinstance(meth, property): |
| |
| |
| |
| meth = meth.fget |
| else: |
| try: |
| meth = meth.__func__ |
| except AttributeError: |
| meth = meth.__get__(cls, typ) |
| except (AttributeError, TypeError): |
| continue |
| if meth.func_code is code: |
| return typ |
| |
|
|
| raise TypeError |
|
|
|
|
| def superm(*args, **kwds): |
| f = sys._getframe(1) |
| nm = f.f_code.co_name |
| return getattr(newsuper(framedepth=2),nm)(*args, **kwds) |
|
|
|
|
| __all__ = ['newsuper'] |
|
|