Signals in Godot 4

In Godot 4 a signal is a first-class Signal value and a method reference is a Callable. Use the object syntax (button.pressed.connect(_on_pressed)) everywhere. The parser then rejects a misspelled handler, and a misspelled signal on self; a misspelled signal on another typed node is caught when unsafe_property_access is set to Error (see the godot-4-api-pitfalls skill). The string forms (connect("pressed", ...), emit_signal("died")) are only checked at runtime.

Declare, emit, connect

extends Node

signal health_changed(old_value: int, new_value: int)
signal died

var health := 100