Add pluggable components.

 - Adds the notion of a 'plugin'.
   - A plugin has a package path and a flag specifying whether
     it's enabled or not.

 - Adds a find_pluggable_components function similar to the
   find_components one. This one dynamically searches not only
   the mailman package but all of plugins.
   - e.g. find_pluggable_components('rules', IRule) finds
     all IRule components in mailman.rules but also in
     example_plugin.rules for plugin names example_plugin.

 - Uses the find_pluggable_components function in place of
   find_components when searching for Rules, Handlers, Chains,
   EmailCommands, and Styles.

1 files changed, 6 insertions, 1 deletions

diff --git a/src/mailman/config/config.py b/src/mailman/config/config.py
index 61c9fe6ed..2ba657905 100644
--- a/src/mailman/config/config.py
+++ b/src/mailman/config/config.py
@@ -158,7 +158,7 @@ class Configuration:
                 else category.template_dir),
             )
         # Directories.
-        for name in ('archive', 'bin', 'cache', 'data', 'etc', 'ext',
+        for name in ('archive', 'bin', 'cache', 'data', 'etc',
                      'list_data', 'lock', 'log', 'messages', 'queue'):
             key = '{}_dir'.format(name)
             substitutions[key] = getattr(category, key)
@@ -248,6 +248,11 @@ class Configuration:
             yield archiver
 
     @property
+    def plugin_configs(self):
+        """Iterate over all the plugin configuration sections."""
+        return self._config.getByCategory('plugin', [])
+
+    @property
     def language_configs(self):
         """Iterate over all the language configuration sections."""
         yield from self._config.getByCategory('language', [])