name : plugin_loader.py import tuned.logs import os __all__ = ["PluginLoader"] log = tuned.logs.get() class PluginLoader(object): __slots__ = ["_namespace", "_prefix", "_interface"] def _set_loader_parameters(self): """ This method has to be implemented in child class and should set _namespace, _prefix, and _interface member attributes. """ raise NotImplementedError() def __init__(self): super(PluginLoader, self).__init__() self._namespace = None self._prefix = None self._interface = None self._set_loader_parameters() assert type(self._namespace) is str assert type(self._prefix) is str assert type(self._interface) is type and issubclass(self._interface, object) def load_plugin(self, plugin_name): assert type(plugin_name) is str module_name = "%s.%s%s" % (self._namespace, self._prefix, plugin_name) return self._get_class(module_name) def _get_class(self, module_name): log.debug("loading module %s" % module_name) module = __import__(module_name) path = module_name.split(".") path.pop(0) while len(path) > 0: module = getattr(module, path.pop(0)) for name in module.__dict__: cls = getattr(module, name) if type(cls) is type and issubclass(cls, self._interface): return cls raise ImportError("Cannot find the plugin class.") def load_all_plugins(self): plugins_package = __import__(self._namespace) plugin_clss = [] for module_name in os.listdir(plugins_package.plugins.__path__[0]): try: module_name = os.path.splitext(module_name)[0] if not module_name.startswith("plugin_"): continue plugin_class = self._get_class( "%s.%s" % (self._namespace, module_name) ) if plugin_class not in plugin_clss: plugin_clss.append(plugin_class) except ImportError: pass return plugin_clss