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|
# GNU MediaGoblin -- federated, autonomous media hosting
# Copyright (C) 2011, 2012 MediaGoblin contributors. See AUTHORS.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
This module implements the plugin api bits.
Two things about things in this module:
1. they should be excessively well documented because we should pull
from this file for the docs
2. they should be well tested
How do plugins work?
====================
Plugins are structured like any Python project. You create a Python package.
In that package, you define a high-level ``__init__.py`` module that has a
``hooks`` dict that maps hooks to callables that implement those hooks.
Additionally, you want a LICENSE file that specifies the license and a
``setup.py`` that specifies the metadata for packaging your plugin. A rough
file structure could look like this::
myplugin/
|- setup.py # plugin project packaging metadata
|- README # holds plugin project information
|- LICENSE # holds license information
|- myplugin/ # plugin package directory
|- __init__.py # has hooks dict and code
Lifecycle
=========
1. All the modules listed as subsections of the ``plugins`` section in
the config file are imported. MediaGoblin registers any hooks in
the ``hooks`` dict of those modules.
2. After all plugin modules are imported, the ``setup`` hook is called
allowing plugins to do any set up they need to do.
"""
import logging
from functools import wraps
from mediagoblin import mg_globals
_log = logging.getLogger(__name__)
class PluginManager(object):
"""Manager for plugin things
.. Note::
This is a Borg class--there is one and only one of this class.
"""
__state = {
# list of plugin classes
"plugins": [],
# map of hook names -> list of callables for that hook
"hooks": {},
# list of registered template paths
"template_paths": set(),
# list of registered routes
"routes": [],
}
def clear(self):
"""This is only useful for testing."""
# Why lists don't have a clear is not clear.
del self.plugins[:]
del self.routes[:]
self.hooks.clear()
self.template_paths.clear()
def __init__(self):
self.__dict__ = self.__state
def register_plugin(self, plugin):
"""Registers a plugin class"""
self.plugins.append(plugin)
def register_hooks(self, hook_mapping):
"""Takes a hook_mapping and registers all the hooks"""
for hook, callables in hook_mapping.items():
if isinstance(callables, (list, tuple)):
self.hooks.setdefault(hook, []).extend(list(callables))
else:
# In this case, it's actually a single callable---not a
# list of callables.
self.hooks.setdefault(hook, []).append(callables)
def get_hook_callables(self, hook_name):
return self.hooks.get(hook_name, [])
def register_template_path(self, path):
"""Registers a template path"""
self.template_paths.add(path)
def get_template_paths(self):
"""Returns a tuple of registered template paths"""
return tuple(self.template_paths)
def register_route(self, route):
"""Registers a single route"""
self.routes.append(route)
def get_routes(self):
return tuple(self.routes)
def register_routes(routes):
"""Registers one or more routes
If your plugin handles requests, then you need to call this with
the routes your plugin handles.
A "route" is a `routes.Route` object. See `the routes.Route
documentation
<http://routes.readthedocs.org/en/latest/modules/route.html>`_ for
more details.
Example passing in a single route:
>>> from routes import Route
>>> register_routes(Route('about-view', '/about',
... controller=about_view_handler))
Example passing in a list of routes:
>>> from routes import Route
>>> register_routes([
... Route('contact-view', '/contact', controller=contact_handler),
... Route('about-view', '/about', controller=about_handler)
... ])
.. Note::
Be careful when designing your route urls. If they clash with
core urls, then it could result in DISASTER!
"""
if isinstance(routes, (tuple, list)):
for route in routes:
PluginManager().register_route(route)
else:
PluginManager().register_route(routes)
def register_template_path(path):
"""Registers a path for template loading
If your plugin has templates, then you need to call this with
the absolute path of the root of templates directory.
Example:
>>> my_plugin_dir = os.path.dirname(__file__)
>>> template_dir = os.path.join(my_plugin_dir, 'templates')
>>> register_template_path(template_dir)
.. Note::
You can only do this in `setup_plugins()`. Doing this after
that will have no effect on template loading.
"""
PluginManager().register_template_path(path)
def get_config(key):
"""Retrieves the configuration for a specified plugin by key
Example:
>>> get_config('mediagoblin.plugins.sampleplugin')
{'foo': 'bar'}
>>> get_config('myplugin')
{}
>>> get_config('flatpages')
{'directory': '/srv/mediagoblin/pages', 'nesting': 1}}
"""
global_config = mg_globals.global_config
plugin_section = global_config.get('plugins', {})
return plugin_section.get(key, {})
|
