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"""
Plugin
------
Classes for representing and loading plugins.
"""
import os
import importlib
class PluginRegistry(type):
"""
Metaclass that registers any classes using it in the `plugins` array
"""
plugins = []
def __init__(cls, name, bases, attrs):
if name != 'Plugin' and cls.__name__ not in map(lambda x: x.__name__, PluginRegistry.plugins):
PluginRegistry.plugins.append(cls)
class Plugin(metaclass=PluginRegistry):
"""
Top-level plugin class, using the PluginRegistry metaclass.
All plugin modules must implement a single subclass of this class. This
subclass will be the class collected in the PluginRegistry, and should
contain references to any other resources required within the module.
"""
class PluginManager(object):
"""
Loads plugins which are automatically registered with the PluginRegistry
class, and provides an interface to the plugin collection.
"""
def load_plugins(self, directory):
"""
Loads plugins from the specified directory.
`directory` is the full path to a directory containing python modules
which each contain a subclass of the Plugin class.
There is no criteria for a valid plugin at this level - any python
module found in the directory will be loaded. Only modules that
implement a subclass of the Plugin class above will be collected.
The directory will be traversed recursively.
"""
# walk directory
for filename in os.listdir(directory):
# path to file
filepath = os.path.join(directory, filename)
# if it's a file, load it
modname, ext = os.path.splitext(filename)
if os.path.isfile(filepath) and ext == '.py':
spec = importlib.util.spec_from_file_location(modname, filepath)
if spec:
mod = importlib.util.module_from_spec(spec)
spec.loader.exec_module(mod)
# if it's a directory, recurse into it
if os.path.isdir(filepath):
self.load_plugins(filepath)
@property
def plugins(self):
return PluginRegistry.plugins
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