emit_signal
- Game Development course
- Intermediate
- Lesson 71/83
- 4 min
Learn to emit a signal with emit_signal.
Emitting signals: emit and emit_signal
To trigger a signal and notify listeners, you emit it. In Godot 4, the most common way is calling signal_name.emit(); alternatively, the object-level emit_signal("signal_name") method can also be used.
signal health_changed(new_health)
func take_damage(amount: int):
health -= amount
health_changed.emit(health) # Triggers the signalAs soon as this line runs, all functions connected to the signal are executed in order.
Emitting signals with parameters
Parameters declared on the signal are passed as arguments to emit() or emit_signal() in sequence.
signal score_added(points, player_id)
func add_score():
score_added.emit(100, 1)
# or: emit_signal("score_added", 100, 1)If the parameter count or types do not match, Godot will generate an error or warning.
Practice Emit and handle signal
Declare signal alert_triggered(msg). In _ready, connect it to _on_alert and call alert_triggered.emit("Tehlike!"). The function should print the message.
Starter code
extends Node
signal alert_triggered(msg)
func _ready():
# Bagla ve emit et
func _on_alert(msg):
print(msg)Sample solution
extends Node
signal alert_triggered(msg)
func _ready():
alert_triggered.connect(_on_alert)
alert_triggered.emit("Tehlike!")
func _on_alert(msg):
print(msg)Expected output
Tehlike!
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What is the most common modern syntax to emit a custom signal named 'oyun_bitti' in Godot 4?
- trigger(oyun_bitti)
- oyun_bitti.fire()
- send_signal("oyun_bitti")
- oyun_bitti.emit() Correct answer
Explanation: In Godot 4, signal objects have a direct 'emit()' method (e.g., oyun_bitti.emit()).
2 Trigger signal
signal level_up
func finish_quest():
level_up.____()signal level_up
func finish_quest():
level_up.emit()Explanation: In Godot 4, .emit() is called on the signal object to trigger it.
3 Emitting and triggering terms
| Term | Meaning |
|---|---|
emit() |
Directly triggers the signal |
emit_signal |
Method to emit signal by name |
Argümanlar |
Data carried to listeners |
Handler |
Function handling the signal |