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# Copyright 2010 Google Inc.
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish, dis-
# tribute, sublicense, and/or sell copies of the Software, and to permit
# persons to whom the Software is furnished to do so, subject to the fol-
# lowing conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABIL-
# ITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
# SHALL THE AUTHOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
# IN THE SOFTWARE.
"""
Implements plugin related api.
To define a new plugin just subclass Plugin, like this.
class AuthPlugin(Plugin):
pass
Then start creating subclasses of your new plugin.
class MyFancyAuth(AuthPlugin):
capability = ['sign', 'vmac']
The actual interface is duck typed.
"""
import glob
import imp
import os.path
class Plugin(object):
"""Base class for all plugins."""
capability = []
@classmethod
def is_capable(cls, requested_capability):
"""Returns true if the requested capability is supported by this plugin
"""
for c in requested_capability:
if c not in cls.capability:
return False
return True
def get_plugin(cls, requested_capability=None):
if not requested_capability:
requested_capability = []
result = []
for handler in cls.__subclasses__():
if handler.is_capable(requested_capability):
result.append(handler)
return result
def _import_module(filename):
(path, name) = os.path.split(filename)
(name, ext) = os.path.splitext(name)
(file, filename, data) = imp.find_module(name, [path])
try:
return imp.load_module(name, file, filename, data)
finally:
if file:
file.close()
_plugin_loaded = False
def load_plugins(config):
global _plugin_loaded
if _plugin_loaded:
return
_plugin_loaded = True
if not config.has_option('Plugin', 'plugin_directory'):
return
directory = config.get('Plugin', 'plugin_directory')
for file in glob.glob(os.path.join(directory, '*.py')):
_import_module(file)
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