observable_properties.gd

extends Node2D

class ObservableProperty extends Node:
	var _value: Variant
	signal _value_changed(old_value, new_value)
	
	func _set(property: StringName, value: Variant) -> bool:
		if property == "value":
			var old_value = _value
			self._value = value
			self._value_changed.emit(old_value, _value)
			return true
		return false
	
	
		
class GameProperties extends Node:
	var properties = {
		"speed": null,
		"distance": null
	}
	func _set(property: StringName, value: Variant) -> bool:
		if property in properties:
			if properties[property] == null:
				properties[property] = ObservableProperty.new()
			if value is Callable:
				properties[property]._value_changed.connect(value)
				return true
			else:
				properties[property].value = value
				return true
		return false
		
	func _get(property: StringName) -> Variant:
		if property in properties:
			return properties[property]._value
		return null
	

func on_speed_changed(old_value, new_value):
	print("Old speed value: %s\nNew speed value: %s" % [old_value, new_value])
	
func on_distance_changed(old_value, new_value):
	print("Old distance value: %s\nNew distance value: %s" % [old_value, new_value])

func _init():
	var props = GameProperties.new()
	props.speed = on_speed_changed
	props.speed = 1.0
	print()
	props.speed = 1.5
	
	print()
	
	print("Speed: %s" % props.speed)
	
	print()
	
	print("props.properties['speed'] is ObservableProperty? %s" % props.properties['speed'] is ObservableProperty)
	print("props.speed is ObservableProperty? %s" % props.speed is ObservableProperty)
	print("props.speed is float? %s" % props.speed is float)
	
	print()
	
	props.distance = 500
	props.distance = on_distance_changed
	props.distance = 100
	print()
	props.distance = 1000
	
	print()
	
	print("Distance: %s\n" % props.distance)
	print("props.properties['distance'] is ObservableProperty? %s" % props.properties['distance'] is ObservableProperty)
	print("props.distance is ObservableProperty? %s" % props.distance is ObservableProperty)
	print("props.distance is int? %s" % props.distance is int)
	
	print()
	
	print("All properties: %s" % ", ".join(props.properties.keys()))