add computed properties

freecad/gears/features.py

@@ -103,6 +103,7 @@ class involute_gear(object):
         obj.addProperty(
             "App::PropertyFloat", "head", "gear_parameter", "head_value * modul_value = additional length of head")
         obj.addProperty("App::PropertyPythonObject", "gear", "gear_parameter", "test")
+        obj.addProperty("App::PropertyFloat", "dw", "computed", "roll diameter", 1)
         obj.gear = self.involute_tooth
         obj.simple = False
         obj.undercut = False
@@ -158,6 +159,8 @@ class involute_gear(object):
             rw = fp.gear.dw / 2
             fp.Shape=Part.makeCylinder(rw,fp.height.Value)
 
+        fp.dw = fp.gear.dw
+
     def __getstate__(self):
         return None