Merge branch 'plugins-entrygroup' into 'master'

plugins: Allow entry_points to be registered

See merge request poezio/poezio!67

doc/source/dev/plugin.rst

@@ -1,6 +1,26 @@
 Plugin API documentation
 ========================
 
+External plugins
+----------------
+
+It is possible to create external plugins easily using `setuptools'
+entry_point
+<https://setuptools.readthedocs.io/en/latest/setuptools.html#dynamic-discovery-of-services-and-plugins>`_
+feature. You can register your plugin against the ``poezio_plugins`` entry
+group with the following snippet in your project ``setup.py``:
+
+.. code-block:: python
+
+    setup(
+        ..
+        packages=['yourmodule'],
+        entry_points{'poezio_plugins': 'yourplugin = yourmodule'},
+        ..
+    )
+
+The plugin will then be available as ``yourplugin`` at runtime.
+
 BasePlugin
 ----------
 

poezio/plugin_manager.py

@@ -10,6 +10,7 @@ import os
 from importlib import import_module, machinery
 from pathlib import Path
 from os import path
+import pkg_resources
 
 from poezio import tabs, xdg
 from poezio.core.structs import Command, Completion
@@ -74,6 +75,14 @@ class PluginManager:
                     module = import_module('poezio_plugins.%s' % name)
                 except ModuleNotFoundError:
                     pass
+            for entry in pkg_resources.iter_entry_points('poezio_plugins'):
+                if entry.name == name:
+                    try:
+                        module = entry.load()
+                    except ImportError:
+                        pass
+                    finally:
+                        break
             if not module:
                 self.core.information('Could not find plugin: %s' % name,
                                       'Error')