worked out a simple way to call a lua function as a method based on the overridable_function_members.cpp

example

src/scripts/demos/simple_000.lua

@@ -70,6 +70,11 @@ local w = pw.window.new()
 -- set title
 w.title = "pixwerx 0.1"
 
+-- setup a lua callback function
+w.on_update = function(self)
+    print("test on update",w.position.x,w.position.y)
+end
+
 -- set size
 w.size = pw.size.new(800,600)
 -- move window