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# -*- coding: utf-8 -*-
# Licensed under the MIT license
# http://opensource.org/licenses/mit-license.php
# Copyright 2007, Frank Scholz <coherence@beebits.net>
""" real simple plugin system
meant as a replacement when setuptools/pkg_resources
are not available
"""
import os
import sys
class Plugin(object):
""" a new style class that
betrays all its sub-classes
"""
pass
class Reception(object):
""" singleton class which holds information
about known plugins
currently a singleton, and even a class,
seems to be overkill for this, but maybe
we'll add some more functionality later
"""
_instance_ = None # Singleton
def __new__(cls, *args, **kwargs):
""" creates the singleton """
obj = getattr(cls,'_instance_',None)
if obj is not None:
return obj
else:
obj = super(Reception, cls).__new__(cls, *args, **kwargs)
cls._instance_ = obj
return obj
def __init__(self,plugin_path=None,log=None):
""" initializes the class and
checks in if a path is provided
"""
self.log = log
if plugin_path is not None:
self.checkin(plugin_path)
def checkin(self,plugin_path):
""" import all valid files from plugin_path """
if not plugin_path in sys.path:
sys.path.insert(0, plugin_path)
for plugin in os.listdir(plugin_path):
p = os.path.join(plugin_path, plugin)
if plugin != '__init__.py' and os.path.isfile(p) and os.path.splitext(p)[1] == '.py':
try:
__import__(os.path.splitext(plugin)[0], None, None, [''])
except Exception, msg:
if self.log is None:
print "can't import %r - %s" % (os.path.splitext(plugin)[0], msg)
else:
self.log("can't import %r - %r" % (os.path.splitext(plugin)[0], msg))
def guestlist(self, plugin_class=Plugin):
""" returns a list of all Plugin subclasses """
found = []
def get_subclass(klass, subclasses):
if len(subclasses) == 0:
found.append(klass)
else:
for k in subclasses:
get_subclass(k,k.__subclasses__())
get_subclass(plugin_class, plugin_class.__subclasses__())
return found
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