GDScript Setters and Getters: set and get in Godot 4

A setter runs every time a variable is assigned. A getter runs every time it is read. In Godot 4 you write them right under the variable:

extends Node

var max_hp := 100
var hp := 100:
	set(value):
		hp = clampi(value, 0, max_hp)
		print("hp is now ", hp)

func _ready():
	hp -= 30
	hp += 500    # clamped to 100
	hp = -5      # clamped to 0

hp is now 70
hp is now 100
hp is now 0

• set(value): receives the new value. Inside it, hp = ... stores the value directly, without calling the setter again.
• The setter runs for every assignment, including += and assignments from the script's own functions.
• The starting value, 100 here, is stored without running the setter.

Getters and Computed Properties

A getter that returns a value worked out from other variables makes a computed property:

extends Node

var hp := 40
var max_hp := 100

var hp_percent: float:
	get:
		return 100.0 * hp / max_hp

var is_dead: bool:
	get:
		return hp <= 0

func _ready():
	print(hp_percent)
	hp = 0
	print(is_dead)

40.0
true

GDScript has no true read-only property. Assigning to hp_percent is allowed but has no effect on what it returns, because the getter never reads the stored value. Leave such a property unassigned, or add a setter that calls push_error().

Setter and Getter Functions

For longer logic, point the property at named functions with set = and get =:

extends Node

var _speed := 1.0
var speed: float:
	set = set_speed, get = get_speed

func set_speed(value: float) -> void:
	_speed = maxf(value, 0.0)

func get_speed() -> float:
	return _speed

func _ready():
	speed = -3.0
	print(speed)
	set_speed(250.0)
	print(speed)

0.0
250.0

This form is also what Godot 3's setget turned into: var speed setget set_speed, get_speed is now var speed: set = set_speed, get = get_speed.

Reacting to a Change

The most useful setter emits a signal, so the UI updates whenever the value changes and nothing else has to remember to tell it:

extends Node

signal coins_changed(new_amount: int)

var coins := 0:
	set(value):
		coins = value
		coins_changed.emit(coins)

func _ready():
	coins_changed.connect(func(amount): print("Label shows: ", amount))
	coins += 5
	coins += 10

Label shows: 5
Label shows: 15

Setters on Exported Variables

An exported variable's setter runs when Godot loads the saved value, which can be before child nodes are ready. Guard node access with is_node_ready():

@export var color := Color.WHITE:
	set(value):
		color = value
		if is_node_ready():
			$Sprite2D.modulate = color

func _ready():
	$Sprite2D.modulate = color

To see the change in the editor, not only in the running game, add @tool at the top of the script.

Common Mistakes

• A setter that never stores the value. If the setter only prints, the variable keeps its old value. Assign it inside the setter.
• Heavy work in a getter. A getter runs on every read, so a getter that loops over 1,000 nodes runs that loop each time.