Difficult to work with Area2D/PhysicsBody2D in C# due to duplicated code in Godot Engine

[JarLowrey]

Godot version:

3.0.6

Issue description:

I have a situation where a node could be an Area2D or a PhysicsBody2D. These two classes each individually implement collision_layer and collision_mask, even though they are the only children of their direct parent, CollisionLayer2D. This is fine for GDScript, but causes issues in a compiled language like C#.

Looking at the code for Area2D and PhysicsBody2D, it looks like the getters/setters are pretty much identical. Can this logic be refactored out to their shared parent? Removing duplicated code would also improve the maintainability of the engine.

[neikeq]

Removing the topic:mono label as this is an issue with the Godot API. What is proposed here is for CollisionLayer2D to declare collision_layer and collision_mask, instead of doing that in their two derived classes.