Fix node internal properties with extension methods

Author: alessiostalla

pylasu/support.py

@@ -1,3 +1,12 @@
+from pylasu.model.model import Concept
+
+
+def register_internal_property(cls, name):
+    cls.__internal_properties__.append(name)
+    for s in cls.__subclasses__():
+        register_internal_property(s, name)
+
+
 def extension_method(cls):
     """Installs the decorated function as an extension method on cls.
     See https://mail.python.org/pipermail/python-dev/2008-January/076194.html"""
@@ -6,5 +15,7 @@ def decorator(func):
         if name in cls.__dict__:
             raise Exception(f"{cls} already has a member called {name}")
         setattr(cls, name, func)
+        if isinstance(cls, Concept):
+            register_internal_property(cls, name)
         return func
     return decorator

tests/model/test_model.py

@@ -5,6 +5,7 @@
 from pylasu.model import Node, Position, Point
 from pylasu.model.reflection import Multiplicity
 from pylasu.model.naming import ReferenceByName, Named, Scope, Symbol
+from pylasu.support import extension_method
 
 
 @dataclasses.dataclass
@@ -144,6 +145,10 @@ def test_scope_case_insensitive_lookup(self):
         self.assertIsInstance(result, Symbol)
 
     def test_node_properties_meta(self):
+        @extension_method(Node)
+        def frob_node(_: Node):
+            pass
+
         pds = [pd for pd in sorted(SomeNode.node_properties, key=lambda x: x.name)]
         self.assertEqual(5, len(pds), f"{pds} should be 5")
         self.assertEqual("bar", pds[0].name)