Godot scene instantiation from class_name

example.gd

extends Node


func _ready() -> void:
	# MyScene is is a `class_name` in a `.gd` script with an associated `.tscn` file
	var scene = Instantiate.scene(MyScene)
	add_child(scene)

instantiate.gd

class_name Instantiate
extends Object


## Instantiates a scene based on [param clss_name]. Scene must be located next
## to the associated class.
static func scene(clss_name: Variant) -> Node:
	var scn_path := scene_path(clss_name)
	var scn: PackedScene = ResourceLoader.load(scn_path)
	var node := scn.instantiate()
	return node


static func scene_path(clss_name: Variant) -> String:
	var clss_path := (clss_name as Resource).resource_path
	assert(clss_path.ends_with(".gd"), "missing script for class")
	var scn_path := clss_path.substr(0, clss_path.rfind(".gd")) + ".tscn"
	assert(ResourceLoader.exists(scn_path), "missing scene for class")
	return scn_path