| """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: |
| 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 |
|
|
