GDScript: Add keyword to access the current class

[ChibiDenDen]

Describe the project you are working on:
gdscript

Describe the problem or limitation you are having in your project:
No access to class from the following places:

1. From static functions when unnamed Can't use new() or reference own class name in static function (fixed in master) godot#27491
   Mostly for factory methods trying to call new

2. As type from within the same class when unnamed
   For example:

   • As return type for function
   • As variable type
   • etc..

3. As type from within the same class even when named
   Allow scripts marked with class_name to use their class within the script without causing a cyclic dependency godot#25252

Describe how this feature / enhancement will help you overcome this problem or limitation:
The keyword will allow access to the “static_class” Type, thus allowing access to the class type without giving it a name
Show a mock up screenshots/video or a flow diagram explaining how your proposal will work:
Factory function with this_class return type, this_class local variable and access to this_class.new:

func make_with_color(color) -> this_class:
	var obj : this_class = this_class.new()
	obj.color = color
	return obj

Describe implementation detail for your proposal (in code), if possible:
This will be implemented as an additional keyword to the parser and compiler of gdscript
the keyword I used for my POC was "this_class" but I would be more than happy to hear any better suggestions.
See Commit for actual code:
ChibiDenDen/godot@2ff8c1b

If this enhancement will not be used often, can it be worked around with a few lines of script?:
The current “script” solution is to use the following expression to get the static class
load(“res://path_to_script_file.gd”)
Which is a hacky way, creates a dependency on the scripts path and looks bad
Furthermore, this is not documented and very hard for new users to find.

Is there a reason why this should be core and not an add-on in the asset library?:
This is part of gdscript syntax

[KoBeWi]

What if we go full-Ruby and just make self.class (or similar) return the current class? No need for another keyword then.

[ChibiDenDen]

since self should return an instance of the class self is not accessible from most of the cases:
static function
type specifier for functions (args / return value)

[Calinou]

You can use get_script().new() to create a new instance of the current class. However, you can't use it in static functions as you pointed out.

[ChibiDenDen]

I know, but this is not consistent, for example, in an inner class, would this line create an instance of the inner class, or of the top-level class in the script?
I feel like some method of referring to the class type is required, specifically since most top-level classes are anonymous, and since the class_name keyword is very noisy and limiting (makes the class a global class accessible from everywhere, not allowing self referencing)

[Xrayez]

If only get_script could be static somehow indeed. I've tried to simplify the process of instancing scenes. The script path can determine a scene path assuming both scene and script remain in the same directory:

static func instance():
    return load(get_script().resource_path.get_basename() + ".tscn").instance()

It means that I could instance a scene from within global class_name without hardcoding the scene path.

var player = Player.instance()

See also #260.

[me2beats]

Should a static function be called "static" in such a case?

[bluenote10]

the keyword I used for my POC was "this_class" but I would be more than happy to hear any better suggestions.

The problem with this_class could be that it is lower case and uses underscore. Typically types are PascalCase so a reader may get confused that this_class is supposed to refer to a type.

The same mechanism exists in Rust, and there it is called Self, which makes it very obvious that Self is the type of self.

[me2beats]

The problem I have now is I can't make these functions static and move them to my Utils class (NodeUtils):

func get_children_sorted_by_x(node:Control)->Array:
	var children = node.get_children().duplicate()
	children.sort_custom(self, '_sort_by_x')
	return children


func _sort_by_x(a:Control, b:Control):
	if a.rect_position.x<b.rect_position.x:
		return true
	return false

this is because of self in sort_custom()

I work-round it by creating SortUtils class and moving _sort_by_x() there so

node_utils.gd:

const SortUtils = preload("res://sort_utils.gd")

static func get_children_sorted_by_x(node:Control)->Array:
	var children = node.get_children().duplicate()
	children.sort_custom(SortUtils, '_sort_by_x')
	return children

sort_utils.gd:

static func _sort_by_x(a:Control, b:Control):
	if a.rect_position.x<b.rect_position.x:
		return true
	return false

this is not so convenient tho.

The thing I tried to achieve is reusable get_children_sorted_by_x() without inheritance or creating multiple objects. Also I don't want to use singletons for that.