Turbofish support for node.duplicate()

[Relu-Avali]

When duplicating a node of a known sub-node type such as

let original = Sprite2D.new_alloc();
let duplicate = original_node.duplicate().unwrap(); //will be of type Gd<Node> 
let cast_duplicate = duplicate.cast::<Sprite2D>();
//You can now do Sprite2D stuff with your duplicate here

the duplicate will be a Gd<Node> instead of the same type as the original. If you intend to do anything with the duplicate it will require down-casting to the type of the original. I suggest adding turbofish support for duplicate in order to reduce the number of required casts.

Example of suggestion:

let original = Sprite2D.new_alloc();
let my_duplicate = original_node.duplicate::<Sprite2D>();
//You can now do Sprite2D stuff with your duplicate here

[Bromeon]

I don't think it should have a generic argument (turbofish support), but rather be a trait method that always returns Gd<Self>. (Outside a trait, it would need to be redeclared for each class.)

Or, have the method directly on Gd rather than the class types.

[Relu-Avali]

I don't think it should have a generic argument (turbofish support), but rather be a trait method that always returns Gd<Self>. (Outside a trait, it would need to be redeclared for each class.)

Or, have the method directly on Gd rather than the class types.

My idea with having it as generic argument was that if for some reason you wanted it as a different sub type, such has a Node2D, you could have it.

let original = Sprite2D.new_alloc();
let my_duplicate = original_node.duplicate::<Node2D>();
//You can now do Node2D stuff with your duplicate here

Aside from that very use specific use case I do agree that trait methods sounds like a much better solution.

[Bromeon]

duplicate is not really special in that regard, like clone the natural thing would be to return the same type. The user can always upcast if needed (i.e. throw type information away). But FYI you can do all Node2D stuff on Sprite2D, the methods are "inherited".

Semi-related: #695