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
