| | """Simple plug-in mechanism to provide replacement for setuptools plugins""" |
| |
|
| | class Plugin( object ): |
| | """Base class for plugins to be loaded""" |
| | loaded = False |
| | def __init__( self, name, import_path, check = None, **named ): |
| | """Register the plug-in""" |
| | self.name = name |
| | self.import_path = import_path |
| | self.check = check |
| | self.registry.append( self ) |
| | self.__dict__.update( named ) |
| | def load( self ): |
| | """Attempt to load and return our entry point""" |
| | try: |
| | return importByName( self.import_path ) |
| | except ImportError as err: |
| | return None |
| | @classmethod |
| | def match( cls, *args ): |
| | """Match to return the plugin which is appropriate to load""" |
| | @classmethod |
| | def all( cls ): |
| | """Iterate over all registered plugins""" |
| | return cls.registry[:] |
| | @classmethod |
| | def by_name( cls, name ): |
| | for instance in cls.all(): |
| | if instance.name == name: |
| | return instance |
| | return None |
| | |
| | def importByName( fullName ): |
| | """Import a class by name""" |
| | name = fullName.split(".") |
| | moduleName = name[:-1] |
| | className = name[-1] |
| | module = __import__( ".".join(moduleName), {}, {}, moduleName) |
| | return getattr( module, className ) |
| |
|
| | |
| | class PlatformPlugin( Plugin ): |
| | """Platform-level plugin registration""" |
| | registry = [] |
| | @classmethod |
| | def match( cls, key ): |
| | """Determine what platform module to load |
| | |
| | key -- (sys.platform,os.name) key to load |
| | """ |
| | for possible in key: |
| | |
| | for plugin in cls.registry: |
| | if plugin.name == possible: |
| | return plugin |
| | raise KeyError( """No platform plugin registered for %s"""%(key,)) |
| |
|
| | class FormatHandler( Plugin ): |
| | """Data-type storage-format handler""" |
| | registry = [] |
| | @classmethod |
| | def match( cls, value ): |
| | """Lookup appropriate handler based on value (a type)""" |
| | key = '%s.%s'%( value.__module__, value.__name__ ) |
| | for plugin in cls.registry: |
| | set = getattr( plugin, 'check', ()) |
| | if set and key in set: |
| | return plugin |
| | return None |
| |
|
