Add tool internal variables in gdscript

[credman0]

It would be useful to have a variable that tools can use to track state that can change from within the editor. For example:

func _enter_tree():
    counter+=1

_enter_tree will be called once by the editor, and then once by the game. But counter will be reset to 0 when the game is run. A flawed workaround does exist using export, ie

export var counter = 0
func _enter_tree():
    counter+=1

but this causes the variable to be editable from within the editor's Inspector, which is not ideal for a variable meant to track the internal state of the node. I request something like maybe this:

export (null) var counter = 0
func _enter_tree():
    counter+=1

which prevents the variable from appearing in the Inspector.

[2shady4u]

How about using Engine.is_editor_hint() to distinguish between counter updates? But I guess you want something more than that?
I think it is really unintuitive to have an export variable that is NOT appearing in the editor sidebar....

This is a duplicate of this btw:
#5988

[KoBeWi]

Closing as duplicate of #5988