# (C) Copyright 2007-2019 Enthought, Inc., Austin, TX # All rights reserved. # # This software is provided without warranty under the terms of the BSD # license included in LICENSE.txt and may be redistributed only # under the conditions described in the aforementioned license. The license # is also available online at http://www.enthought.com/licenses/BSD.txt # Thanks for using Enthought open source! """ A simple plugin manager implementation. """ from fnmatch import fnmatch import logging from traits.api import Event, HasTraits, Instance, List, Str, provides from .i_application import IApplication from .i_plugin import IPlugin from .i_plugin_manager import IPluginManager from .plugin_event import PluginEvent logger = logging.getLogger(__name__) @provides(IPluginManager) class PluginManager(HasTraits): """ A simple plugin manager implementation. This implementation manages an explicit collection of plugin instances, e.g:: plugin_manager = PluginManager( plugins = [ MyPlugin(), YourPlugin() ] ) Plugins can be added and removed after construction time via the methods 'add_plugin' and 'remove_plugin'. """ #### 'IPluginManager' protocol ############################################# # Fired when a plugin has been added to the manager. plugin_added = Event(PluginEvent) # Fired when a plugin has been removed from the manager. plugin_removed = Event(PluginEvent) #### 'PluginManager' protocol ############################################## # The application that the plugin manager is part of. application = Instance(IApplication) def _application_changed(self, trait_name, old, new): """ Static trait change handler. """ self._update_plugin_application([], self._plugins) return # An optional list of the Ids of the plugins that are to be excluded by # the manager. # # Each item in the list is actually an 'fnmatch' expression. exclude = List(Str) # An optional list of the Ids of the plugins that are to be included by # the manager (i.e. *only* plugins with Ids in this list will be added to # the manager). # # Each item in the list is actually an 'fnmatch' expression. include = List(Str) #### 'object' protocol ##################################################### def __init__(self, plugins=None, **traits): """ Constructor. We allow the caller to specify an initial list of plugins, but the list itself is not part of the public API. To add and remove plugins after construction, use the 'add_plugin' and 'remove_plugin' methods respectively. The manager is also iterable, so to iterate over the plugins use 'for plugin in plugin_manager'. """ super(PluginManager, self).__init__(**traits) if plugins is not None: self._plugins = plugins return def __iter__(self): """ Return an iterator over the manager's plugins. """ plugins = [ plugin for plugin in self._plugins if self._include_plugin(plugin.id) ] return iter(plugins) #### 'IPluginManager' protocol ############################################# def add_plugin(self, plugin): """ Add a plugin to the manager. """ self._plugins.append(plugin) self.plugin_added = PluginEvent(plugin=plugin) return def get_plugin(self, plugin_id): """ Return the plugin with the specified Id. """ for plugin in self._plugins: if plugin_id == plugin.id: if not self._include_plugin(plugin.id): plugin = None break else: plugin = None return plugin def remove_plugin(self, plugin): """ Remove a plugin from the manager. """ self._plugins.remove(plugin) self.plugin_removed = PluginEvent(plugin=plugin) return def start(self): """ Start the plugin manager. """ for plugin in self._plugins: self.start_plugin(plugin) return def start_plugin(self, plugin=None, plugin_id=None): """ Start the specified plugin. """ plugin = plugin or self.get_plugin(plugin_id) if plugin is not None: logger.debug('plugin %s starting', plugin.id) plugin.activator.start_plugin(plugin) logger.debug('plugin %s started', plugin.id) else: raise SystemError('no such plugin %s' % plugin_id) return def stop(self): """ Stop the plugin manager. """ # We stop the plugins in the reverse order that they were started. stop_order = self._plugins[:] stop_order.reverse() for plugin in stop_order: self.stop_plugin(plugin) return def stop_plugin(self, plugin=None, plugin_id=None): """ Stop the specified plugin. """ plugin = plugin or self.get_plugin(plugin_id) if plugin is not None: logger.debug('plugin %s stopping', plugin.id) plugin.activator.stop_plugin(plugin) logger.debug('plugin %s stopped', plugin.id) else: raise SystemError('no such plugin %s' % plugin_id) return #### Protected 'PluginManager' ############################################# # The plugins that the manager manages! _plugins = List(IPlugin) def __plugins_changed(self, trait_name, old, new): """ Static trait change handler. """ self._update_plugin_application(old, new) return def __plugins_items_changed(self, trait_name, old, new): """ Static trait change handler. """ self._update_plugin_application(new.removed, new.added) return def _include_plugin(self, plugin_id): """ Return True if the plugin should be included. This is just shorthand for:- if self._is_included(plugin_id) and not self._is_excluded(plugin_id): ... """ return self._is_included(plugin_id) and not self._is_excluded(plugin_id) #### Private protocol ###################################################### def _is_excluded(self, plugin_id): """ Return True if the plugin Id is excluded. If no 'exclude' patterns are specified then this method returns False for all plugin Ids. """ if len(self.exclude) == 0: return False for pattern in self.exclude: if fnmatch(plugin_id, pattern): return True return False def _is_included(self, plugin_id): """ Return True if the plugin Id is included. If no 'include' patterns are specified then this method returns True for all plugin Ids. """ if len(self.include) == 0: return True for pattern in self.include: if fnmatch(plugin_id, pattern): return True return False def _update_plugin_application(self, removed, added): """ Update the 'application' trait of plugins added/removed. """ for plugin in removed: plugin.application = None for plugin in added: plugin.application = self.application return #### EOF ######################################################################