Make Presentation.update() optional

gaphor/UML/actions/activitynodes.py

@@ -240,9 +240,6 @@ class ForkNodeItem(Presentation[UML.ForkNode], HandlePositionUpdate, Named):
     def ports(self):
         return self._ports
 
-    def update(self, context):
-        pass
-
     def save(self, save_func):
         save_func("matrix", tuple(self.matrix))
         save_func("height", float(self._handles[1].pos.y))

gaphor/UML/interactions/executionspecification.py

@@ -100,9 +100,6 @@ class ExecutionSpecificationItem(
         pt, pb = (h.pos for h in self._handles)
         return Rectangle(pt.x - d / 2, pt.y, d, y1=pb.y)
 
-    def update(self, context):
-        pass
-
     def draw(self, context):
         self.shape.draw(context, self.dimensions())
 

gaphor/core/modeling/diagram.py

@@ -370,8 +370,9 @@ class Diagram(PackageableElement):
 
     def _update_items(self, items):
         for item in items:
-            context = UpdateContext(style=self.style(StyledItem(item)))
-            item.update(context)
+            update = getattr(item, "update", None)
+            if update:
+                update(UpdateContext(style=self.style(StyledItem(item))))
 
     def _on_constraint_solved(self, cinfo: gaphas.connections.Connection) -> None:
         dirty_items = set()

gaphor/diagram/presentation.py

@@ -221,9 +221,6 @@ class LinePresentation(gaphas.Line, HandlePositionUpdate, Presentation[S]):
         self.remove_watch_handle(handle)
         super().remove_handle(handle)
 
-    def update(self, context):
-        pass
-
     def update_shape_bounds(self, context):
         def shape_bounds(shape, align):
             if shape: