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# Copyright (C) 2010 Canonical
#
# Authors:
# Lars Wirzenius
# Michael Vogt
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation; version 3.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
import imp
import inspect
import os
import logging
LOG = logging.getLogger(__name__)
from utils import ExecutionTime
class Plugin(object):
"""Base class for plugins.
"""
def init_plugin(self):
""" Init the plugin (UI, connect signals etc)
This should be overwriten by the individual plugins
and should return as fast as possible. if some longer
init is required, start a glib timer or a thread
"""
class PluginManager(object):
"""Class to find and load plugins.
Plugins are stored in files named '*_plugin.py' in the list of
directories given to the initializer.
"""
def __init__(self, app, plugin_dirs):
self._app = app
if isinstance(plugin_dirs, basestring):
plugin_dirs = [plugin_dirs]
self._plugin_dirs = plugin_dirs
self._plugins = None
def get_plugin_files(self):
"""Return all filenames in which plugins may be stored."""
names = []
for dirname in self._plugin_dirs:
if not os.path.exists(dirname):
LOG.debug("no dir '%s'" % dirname)
continue
basenames = [x for x in os.listdir(dirname)
if x.endswith(".py")]
LOG.debug("Plugin modules in %s: %s" %
(dirname, " ".join(basenames)))
names += [os.path.join(dirname, x) for x in basenames]
return names
def _find_plugins(self, module):
"""Find and instantiate all plugins in a module."""
plugins = []
for dummy, member in inspect.getmembers(module):
if inspect.isclass(member) and issubclass(member, Plugin):
plugins.append(member)
LOG.debug("Plugins in %s: %s" %
(module, " ".join(str(x) for x in plugins)))
return [plugin() for plugin in plugins]
def _load_module(self, filename):
"""Load a module from a filename."""
LOG.debug("Loading module %s" % filename)
module_name, dummy = os.path.splitext(os.path.basename(filename))
f = file(filename, "r")
try:
module = imp.load_module(module_name, f, filename,
(".py", "r", imp.PY_SOURCE))
except Exception as e: # pragma: no cover
LOG.warning("Failed to load plugin '%s' (%s)" %
(module_name, e))
return None
f.close()
return module
@property
def plugins(self):
return self._plugins
def load_plugins(self):
"""Return all plugins that have been found.
"""
if self._plugins is None:
self._plugins = []
filenames = self.get_plugin_files()
for filename in filenames:
if not os.path.exists(filename):
LOG.warn("plugin '%s' does not exists, dangling symlink?" % filename)
continue
with ExecutionTime("loading plugin: '%s'" % filename):
module = self._load_module(filename)
for plugin in self._find_plugins(module):
plugin.app = self._app
try:
plugin.init_plugin()
self._plugins.append(plugin)
except:
LOG.exception("failed to init plugin: %s" % module)
# get the matching plugins
plugins = [p for p in self._plugins]
LOG.debug("plugins are '%s'" % plugins)
return plugins
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