godot: Cannot convert self to subclass in the code editor

I am now using the following code snippet, which can be run(This problem doesn’t have much impact on my current project):

func set_player_skill_collision():
	var s = self
	s.collision_layer = 0

I just want to add some common attributes to all types of collision bodies. I think this is very common

TBH I still think that attaching a script to an object of a different type shouldn’t be allowed. It’s currently used by users as a hack but I don’t see it as a good practice. In that sense, the casting self wouldn’t be useful

Even if you can cast self, it gives many other errors if you try to access methods and properties from the actual object when is different from the class you extended. So it’s super bothersome to use even if we remove the casting error

I can make it work as expected with the following, but silly, code:

extends CollisionObject2D

var self2 = self # NOTE: don't use :=
var extends_kinematic := self2 as KinematicBody2D

func _ready() -> void:
	print(true if extends_kinematic else false)

True

This also applies to self is KinematicBody2D.

I think this needs reopened and looked at. Perhaps these errors (in the self comparison case) can be downgraded into warnings?

This is not a bug. It should not allow to convert base class object into a subclass object. It’s against OOP principles. It’s allowed to do vice versa – to convert subclass object into a base class object.

The behavior with conversion of self described above is correct. There is an issue with the first example:

class Super:
	pass
class Sub extends Super:
	pass
var super:Super = Super.new()
var sub:Sub = super as Sub # <<== this results in `null`

In that case the variable sub becomes null and this is expected behavior (see documentation for static typing).

Conversions form base class variables to a subclass is allowed only if the base class variable is actually referencing to a subclass object. For example, this would be a valid case:

class Super:
	pass
class Sub extends Super:
	pass
var super:Super = Sub.new() # <<== variable of type `Super` actually holding object of `Sub`
var sub:Sub = super as Sub # <<== this is correct

@Calinou I believe this issue can be closed.

@Calinou Sorry, my computer can’t support Vulkan

You can run the Godot binary with the --rendering-driver opengl3 --single-window command line arguments to use the experimental OpenGL renderer (currently 2D-only). Note that this will not carry from the project manager to the editor automatically, so you’ll have to open a project directly using the command line for this to work.