godot-gdscript

SKILL.md

Godot GDScript (4.x)

Write correct, statically typed GDScript and use the node lifecycle and signal
system the way the engine intends. Targets Godot 4.7 (GDScript 2.0).

When to use

Use when writing or fixing .gd files: declaring variables, functions, classes,
using @export/@onready, connecting signals, or awaiting coroutines/signals.

Use when porting Godot 3.x scripts to 4.x and the script no longer parses.

When not to use: scene/node structure and instancing questions →
godot-nodes-scenes; signal architecture/decoupling patterns →
godot-signals-groups; using C# instead of GDScript → godot-csharp.

Core workflow

Type everything you can. GDScript 2.0 supports static types
(var hp: int = 10, func add(a: int, b: int) -> int:). Types catch errors at
parse time and speed up the VM. Use := for inferred types.

Use the lifecycle callbacks for their purpose: _ready() once when the node
and its children enter the tree; _process(delta) every rendered frame;
_physics_process(delta) on the fixed physics tick (use it for movement/physics).

Grab node references with @onready, not in _init() — children do not exist
until the node enters the tree.

Expose tunables with @export so designers edit them in the Inspector.

React to events with signals + await, not polling, where it reads cleanly.

Run and read errors. The Debugger panel prints typed errors with line numbers;
fix the first error first (later ones are often cascades).

Patterns

1. A typed script with lifecycle, @export, and @onready

extends Node2D
class_name Spinner            # registers a global type usable in other scripts

@export var speed: float = 90.0          # editable in the Inspector (degrees/sec)
@export_range(0, 10, 0.5) var wobble := 2.0
@onready var sprite: Sprite2D = $Sprite2D # resolved when the node enters the tree

func _ready() -> void:
    # Runs once, after children are ready. Safe to touch $Sprite2D here.
    sprite.modulate = Color.AQUA

func _process(delta: float) -> void:
    # delta is seconds since last frame; multiply rates by it for FPS independence.
    rotation_degrees += speed * delta

2. Signals: declare, emit, connect (4.x Callable syntax)

extends Node

signal health_changed(current: int, maximum: int)   # typed signal params

var health := 100

func take_damage(amount: int) -> void:
    health = max(health - amount, 0)
    health_changed.emit(health, 100)     # 4.x: emit as a method on the signal

func _ready() -> void:
    # 4.x: connect with a Callable, not a string method name.
    health_changed.connect(_on_health_changed)

func _on_health_changed(current: int, maximum: int) -> void:
    print("HP: %d/%d" % [current, maximum])

3. await — pause until a timer or signal fires (replaces 3.x yield)

func flash_then_continue() -> void:
    modulate = Color.RED
    await get_tree().create_timer(0.2).timeout   # resume after 0.2s
    modulate = Color.WHITE
    # await any signal: var result = await some_node.some_signal

4. Lambdas, typed arrays, and safe access

var enemies: Array[Node] = []                    # typed array

func cull_dead() -> void:
    enemies = enemies.filter(func(e): return e.is_inside_tree())

func get_first_name(d: Dictionary) -> String:
    return d.get("name", "unknown")              # default avoids missing-key errors

Pitfalls

3.x → 4.x signal API changed. emit_signal("x") still works but prefer
x.emit(...); connect("x", self, "_on_x") is gone — use x.connect(_on_x) with a
Callable. yield(obj, "sig") is now await obj.sig.

export var is now @export var (annotation). Likewise onready→@onready,
tool→@tool, remote/master RPC keywords → the @rpc(...) annotation.

@onready and $NodePath in _init() fail — the node isn't in the tree yet.
Initialize node references in _ready() or with @onready.

Integer division truncates. 5 / 2 == 2. Use 5.0 / 2 or cast to float.

_process vs _physics_process. Put move_and_slide() and physics in
_physics_process(delta); using _process makes motion frame-rate dependent.

class_name must be unique project-wide and is required to use the type name in
other scripts or as an Inspector type.

References

For the full annotation list, advanced typing, and style conventions, read
references/annotations-and-typing.md.

Related skills

godot-nodes-scenes — the scene tree, instancing, and autoloads.

godot-signals-groups — event-driven architecture with signals and groups.

godot-resources — data-driven design with custom Resource types.

godot-csharp — the same engine concepts using C#/.NET.