On Jun 30, 2007, at 9:32 PM, Jean-Paul Calderone wrote:
On Sat, 30 Jun 2007 20:27:19 -0400, Phil Christensen <phil@bubblehouse.org> wrote:
Hello all,
I'm trying to implement a plugin system in a project using the twisted plugin framework. I've read through the docs pretty thoroughly, but I can't seem to figure out what I'm doing wrong.
Attached is a sample case that should illustrate the problem. The layout is as follows:
plugin_dir/ plugin_dir/test/ plugin_dir/test/plugins/ plugin_dir/test/plugins/myplugin.py test/ test/__init__.py test/plugins/ test/plugins/__init__.py test/sample.py test_plugin.py
First I created the test.plugins package, and included the following in test/plugins/__init__.py:
import os, sys
__path__ = [os.path.abspath(os.path.join(x, 'test', 'plugins')) for x in sys.path]
__all__ = []
Then I created my interfaces in the test.sample module:
from zope import interface
class ISamplePlugin(interface.Interface): '''My Sample Plugin Class'''
Next, I created the plugin in an arbitrary directory, under plugin_dir/test/plugins/myplugin.py:
from zope.interface import implements from twisted import plugin from test.sample import ISamplePlugin
class MyPlugin(object): implements(plugin.IPlugin, ISamplePlugin)
The problem may be here. What happens if you use classProvides instead of implements or bind an instance of MyPlugin to an attribute of this module?
Aha, this looks promising. Doing either of those things results in: Traceback (most recent call last): File "test_plugin.py", line 11, in ? for plugin in plugin_result: File "/Users/phil/Workspace/Twisted/twisted/plugin.py", line 186, in getPlugins allDropins = getCache(package) --- <exception caught here> --- File "/Users/phil/Workspace/Twisted/twisted/plugin.py", line 165, in getCache dropinPath.setContent(pickle.dumps(dropinDotCache)) cPickle.PicklingError: Can't pickle <InterfaceClass test.sample.ISamplePlugin>: import of module test.sample failed <class 'test.plugins.myplugin.MyPlugin'> was found. So this must be pretty close. I tried deleting the dropin.cache, but I'm still getting this exception.
Finally, here's the sample script that tries to load the plugins in the arbitrary directory:
from twisted import plugin
import sys sys.path.append('.') sys.path.append('./plugin_dir')
from test import sample, plugins from twisted import plugin plugin_result = plugin.getPlugins(sample.ISamplePlugin, plugins)
for plugin in plugin_result: print repr(plugin) + ' was found.'