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# plugin.py - plugin base class for computerjanitor
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# Copyright (C) 2008 Canonical, Ltd.
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, version 3 of the License.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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import computerjanitor
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_ = computerjanitor.setup_gettext()
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"""Base class for plugins.
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These plugins only do one thing: identify cruft. See the 'get_cruft'
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def get_condition(self):
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if hasattr(self, "_condition"):
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return self._condition
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def set_condition(self, condition):
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self._condition = condition
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condition = property(get_condition, set_condition)
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def set_application(self, app):
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"""Set the Application instance this plugin belongs to.
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This is used by the plugin manager when creating the plugin
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instance. In a perfect world, this would be done via the
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__init__ method, but since I took a wrong left turn, I ended
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up in an imperfect world, and therefore giving the Application
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instance to __init__ would mandate that all sub-classes would
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have to deal with that explicitly. That is a lot of unnecessary
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make-work, which we should avoid. Therefore, we do it via this
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The class may access the Application instance via the
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def do_cleanup_cruft(self):
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"""Find cruft and clean it up
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This is a helper method
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for cruft in self.get_cruft():
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"""Find some cruft in the system.
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This method MUST return an iterator (see 'yield' statement).
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This interface design allows cruft to be collected piecemeal,
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which makes it easier to show progress in the user interface.
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The base class default implementation of this raises an
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exception. Subclasses MUST override this method.
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raise computerjanitor.UnimplementedMethod(self.get_cruft)
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def post_cleanup(self):
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"""Does plugin wide cleanup after the individual cleanup
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This is useful for stuff that needs to be proccessed
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in batches (e.g. for performance reasons) like package
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class PluginManager(object):
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"""Class to find and load plugins.
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Plugins are stored in files named '*_plugin.py' in the list of
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directories given to the initializer.
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def __init__(self, app, plugin_dirs):
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self._plugin_dirs = plugin_dirs
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def get_plugin_files(self):
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"""Return all filenames in which plugins may be stored."""
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for dirname in self._plugin_dirs:
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basenames = [x for x in os.listdir(dirname)
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if x.endswith("_plugin.py")]
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logging.debug(_("Plugin modules in %s: %s") %
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(dirname, " ".join(basenames)))
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names += [os.path.join(dirname, x) for x in basenames]
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def _find_plugins(self, module):
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"""Find and instantiate all plugins in a module."""
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for dummy, member in inspect.getmembers(module):
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if inspect.isclass(member) and issubclass(member, Plugin):
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plugins.append(member)
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logging.debug(_("Plugins in %s: %s") %
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(module, " ".join(str(x) for x in plugins)))
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return [plugin() for plugin in plugins]
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def _load_module(self, filename):
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"""Load a module from a filename."""
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logging.debug(_("Loading module %s") % filename)
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module_name, dummy = os.path.splitext(os.path.basename(filename))
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f = file(filename, "r")
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module = imp.load_module(module_name, f, filename,
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(".py", "r", imp.PY_SOURCE))
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def get_plugins(self, condition=None, callback=None):
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"""Return all plugins that have been found.
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If callback is specified, it is called after each plugin has
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been found, with the following arguments: filename, index of
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filename in list of files to be examined (starting with 0), and
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total number of files to be examined. The purpose of this is to
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allow the callback to inform the user in case things take a long
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if self._plugins is None:
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filenames = self.get_plugin_files()
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for i in range(len(filenames)):
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callback(filenames[i], i, len(filenames))
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module = self._load_module(filenames[i])
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for plugin in self._find_plugins(module):
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plugin.set_application(self._app)
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self._plugins.append(plugin)
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return [p for p in self._plugins
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if p.condition == condition or condition == "*"]
added
removed
Janitor/computerjanitor/plugin.py
