Implement plugin loading

Signed-off-by: Jacki <jacki@thejackimonster.de>

manuskript/plugin/__init__.py

@@ -0,0 +1,61 @@
+#!/usr/bin/env python
+# --!-- coding: utf8 --!--
+
+from manuskript.plugin.abstractPlugin import AbstractPlugin
+
+import importlib
+import os
+import pkgutil
+import sys
+
+__path__ = pkgutil.extend_path(__path__, __name__)
+
+if sys.version_info < (3, 10):
+    from importlib_metadata import entry_points
+else:
+    from importlib.metadata import entry_points
+
+from importlib.machinery import FileFinder, SourceFileLoader
+
+
+def loadPlugins():
+    plugins = []
+    paths = []
+    
+    for importer in pkgutil.iter_importers():
+        if not importer or type(importer) is not FileFinder:
+            continue
+
+        paths.append(os.path.join(importer.path, 'manuskript', 'plugin'))
+    
+    for module_info in pkgutil.iter_modules(paths):
+        if not module_info or not module_info.ispkg:
+            continue
+
+        name = 'manuskript.plugin.' + module_info.name
+        path = os.path.join(module_info.module_finder.path, module_info.name, '__init__.py')
+
+        try:
+            module = SourceFileLoader(name, path).load_module()
+        except Exception:
+            continue
+
+        try:
+            plugin_cls = module.Plugin
+        except AttributeError:
+            continue
+
+        try:
+            if not issubclass(plugin_cls, AbstractPlugin):
+                continue
+
+            plugin = plugin_cls()
+        except TypeError:
+            continue
+
+        if not plugin:
+            continue
+
+        plugins.append(plugin)
+    
+    return plugins

manuskript/plugin/abstractPlugin.py

@@ -0,0 +1,8 @@
+#!/usr/bin/env python
+# --!-- coding: utf8 --!--
+
+
+class AbstractPlugin:
+
+    def __init__(self):
+        print(" -> " + str(type(self)))

manuskript/plugin/test/__init__.py

@@ -0,0 +1,4 @@
+#!/usr/bin/env python
+# --!-- coding: utf8 --!--
+
+from manuskript.plugin.test.testPlugin import TestPlugin as Plugin

manuskript/plugin/test/testPlugin.py

@@ -0,0 +1,10 @@
+#!/usr/bin/env python
+# --!-- coding: utf8 --!--
+
+from manuskript.plugin import AbstractPlugin
+
+
+class TestPlugin(AbstractPlugin):
+
+    def __init__(self):
+        super().__init__()

manuskript/ui/mainWindow.py

@@ -11,6 +11,7 @@ from gi.repository import GObject, Gtk, Handy
 Handy.init()
 
 from manuskript.data import Project
+from manuskript.plugin import loadPlugins
 from manuskript.ui.views import *
 
 from manuskript.ui.chooser import openFileDialog, saveFileDialog, FileFilter
@@ -27,6 +28,7 @@ from manuskript.util import parseFilenameFromURL
 class MainWindow:
 
     def __init__(self):
+        self.plugins = loadPlugins()
         self.project = None
 
         builder = Gtk.Builder()