GDScript reference

GDScript is a high-level, object-oriented, imperative, and gradually typed programming language built for Godot.

GDScript is a high-level, dynamically typed programming language used to create content. It uses an indentation-based syntax similar to languages like Python. Its goal is to be optimized for and tightly integrated with Godot Engine, allowing great flexibility for content creation and integration.

GDScript is entirely independent from Python and is not based on it.

History

Note

Documentation about GDScript's history has been moved to the Frequently Asked Questions.

Example of GDScript

Some people can learn better by taking a look at the syntax, so here's an example of how GDScript looks.

# Everything after "#" is a comment.
# A file is a class!

# (optional) class definition:
class_name MyClass

# Inheritance:
extends BaseClass

# (optional) icon to show in the editor dialogs:
@icon("res://path/to/optional/icon.svg")


# Member variables.
var a = 5
var s = "Hello"
var arr = [1, 2, 3]
var dict = {"key": "value", 2: 3}
var other_dict = {key = "value", other_key = 2}
var typed_var: int
var inferred_type := "String"

# Constants.
const ANSWER = 42
const THE_NAME = "Charly"

# Enums.
enum {UNIT_NEUTRAL, UNIT_ENEMY, UNIT_ALLY}
enum Named {THING_1, THING_2, ANOTHER_THING = -1}

# Built-in vector types.
var v2 = Vector2(1, 2)
var v3 = Vector3(1, 2, 3)


# Functions.
func some_function(param1, param2, param3):
    const local_const = 5

    if param1 < local_const:
        print(param1)
    elif param2 > 5:
        print(param2)
    else:
        print("Fail!")

    for i in range(20):
        print(i)

    while param2 != 0:
        param2 -= 1

    match param3:
        3:
            print("param3 is 3!")
        _:
            print("param3 is not 3!")

    var local_var = param1 + 3
    return local_var


# Functions override functions with the same name on the base/super class.
# If you still want to call them, use "super":
func something(p1, p2):
    super(p1, p2)


# It's also possible to call another function in the super class:
func other_something(p1, p2):
    super.something(p1, p2)


# Inner class
class Something:
    var a = 10


# Constructor
func _init():
    print("Constructed!")
    var lv = Something.new()
    print(lv.a)

If you have previous experience with statically typed languages such as C, C++, or C# but never used a dynamically typed one before, it is advised you read this tutorial: GDScript: An introduction to dynamic languages.

Language

In the following, an overview is given to GDScript. Details, such as which methods are available to arrays or other objects, should be looked up in the linked class descriptions.

Identifiers

Any string that restricts itself to alphabetic characters (a to z and A to Z), digits (0 to 9) and _ qualifies as an identifier. Additionally, identifiers must not begin with a digit. Identifiers are case-sensitive (foo is different from FOO).

Keywords

The following is the list of keywords supported by the language. Since keywords are reserved words (tokens), they can't be used as identifiers. Operators (like in, not, and or or) and names of built-in types as listed in the following sections are also reserved.

Keywords are defined in the GDScript tokenizer in case you want to take a look under the hood.

Keyword

Description

if

See if/else/elif.

elif

See if/else/elif.

else

See if/else/elif.

for

See for.

while

See while.

match

See match.

break

Exits the execution of the current for or while loop.

continue

Immediately skips to the next iteration of the for or while loop.

pass

Used where a statement is required syntactically but execution of code is undesired, e.g. in empty functions.

return

Returns a value from a function.

class

Defines a class.

class_name

Defines the script as a globally accessible class with the specified name.

extends

Defines what class to extend with the current class.

is

Tests whether a variable extends a given class, or is of a given built-in type.

as

Cast the value to a given type if possible.

self

Refers to current class instance.

signal

Defines a signal.

func

Defines a function.

static

Defines a static function. Static member variables are not allowed.

const

Defines a constant.

enum

Defines an enum.

var

Defines a variable.

breakpoint

Editor helper for debugger breakpoints.

preload

Preloads a class or variable. See Classes as resources.

await

Waits for a signal or a coroutine to finish. See Awaiting for signals.

yield

Previously used for coroutines. Kept as keyword for transition.

assert

Asserts a condition, logs error on failure. Ignored in non-debug builds. See Assert keyword.

void

Used to represent that a function does not return any value.

PI

PI constant.

TAU

TAU constant.

INF

Infinity constant. Used for comparisons and as result of calculations.

NAN

NAN (not a number) constant. Used as impossible result from calculations.

Operators

The following is the list of supported operators and their precedence.

Operator

Description

x[index]

Subscription (highest priority)

x.attribute

Attribute reference

foo()

Function call

is

Instance type checker

~

Bitwise NOT

-x

Negative / Unary negation

* / %

Multiplication / Division / Remainder

These operators have the same behavior as C++. Integer division is truncated rather than returning a fractional number, and the % operator is only available for ints ("fmod" for floats), and is additionally used for Format Strings

+

Addition / Concatenation of arrays

-

Subtraction

<< >>

Bit shifting

&

Bitwise AND

^

Bitwise XOR

|

Bitwise OR

< > == != >= <=

Comparisons

in

Content test

not

Boolean NOT

and

Boolean AND

or

Boolean OR

if x else

Ternary if/else

as

Type casting

= += -= *= /= %= &= |= <<= >>=

Assignment (lowest priority)

Literals

Literal

Type

45

Base 10 integer

0x8f51

Base 16 (hexadecimal) integer

0b101010

Base 2 (binary) integer

3.14, 58.1e-10

Floating-point number (real)

"Hello", "Hi"

Strings

"""Hello"""

Multiline string

&"name"

StringName

^"Node/Label"

NodePath

$NodePath

Shorthand for get_node("NodePath")

Integers and floats can have their numbers separated with _ to make them more readable. The following ways to write numbers are all valid:

12_345_678  # Equal to 12345678.
3.141_592_7  # Equal to 3.1415927.
0x8080_0000_ffff  # Equal to 0x80800000ffff.
0b11_00_11_00  # Equal to 0b11001100.

Annotations

There are some special tokens in GDScript that act like keywords but are not, they are annotations instead. Every annotation start with the @ character and is specified by a name.

Those affect how the script is treated by external tools and usually don't change the behavior.

For instance, you can use it to export a value to the editor:

@export_range(1, 100, 1, "or_greater")
var ranged_var: int = 50

Annotations can be specified one per line or all in the same line. They affect the next statement that isn't an annotation. Annotations can have arguments sent between parentheses and separated by commas.

Both of these are the same:

@export_file("*.png")
@remote
var x

@export_file("*.png") @remote var x

Here's the list of available annotations:

Annotation

Description

@tool

Enable the Tool mode.

@onready

Defer initialization of variable until the node is in the tree. See @onready annotation.

@icon(path)

Set the class icon to show in editor. To be used together with the class_name keyword.

@master

@puppet

@remote

@mastersync

@puppetsync

@remotesync

RPC modifiers. See high-level multiplayer docs.

@export

@export_enum

@export_file

@export_dir

@export_global_file

@export_global_dir

@export_multiline

@export_placeholder

@export_range

@export_exp_easing

@export_color_no_alpha

@export_node_path

@export_flags

@export_flags_2d_render

@export_flags_2d_physics

@export_flags_3d_render

@export_flags_3d_physics

Export hints for the editor. See GDScript exports.

Comments

Anything from a # to the end of the line is ignored and is considered a comment.

# This is a comment.

Built-in types

Built-in types are stack-allocated. They are passed as values. This means a copy is created on each assignment or when passing them as arguments to functions. The only exceptions are Arrays and Dictionaries, which are passed by reference so they are shared. (Packed arrays such as PackedByteArray are still passed as values.)

Basic built-in types

A variable in GDScript can be assigned to several built-in types.

null

null is an empty data type that contains no information and can not be assigned any other value.

bool

Short for "boolean", it can only contain true or false.

int

Short for "integer", it stores whole numbers (positive and negative). It is stored as a 64-bit value, equivalent to "int64_t" in C++.

float

Stores real numbers, including decimals, using floating-point values. It is stored as a 64-bit value, equivalent to "double" in C++. Note: Currently, data structures such as Vector2, Vector3, and PackedFloat32Array store 32-bit single-precision "float" values.

String

A sequence of characters in Unicode format. Strings can contain the following escape sequences:

Escape sequence

Expands to

\n

Newline (line feed)

\t

Horizontal tab character

\r

Carriage return

\a

Alert (beep/bell)

\b

Backspace

\f

Formfeed page break

\v

Vertical tab character

\"

Double quote

\'

Single quote

\\

Backslash

\uXXXX

Unicode codepoint XXXX (hexadecimal, case-insensitive)

Also, using \ followed by a newline inside a string will allow you to continue it in the next line, without inserting a newline character in the string itself.

GDScript also supports GDScript format strings.

StringName

An immutable string that allows only one instance of each name. They are slower to create and may result in waiting for locks when multithreading. In exchange, they're very fast to compare, which makes them good candidates for dictionary keys.

NodePath

A pre-parsed path to a node or a node property. They are useful to interact with the tree to get a node, or affecting properties like with Tweens.

Vector built-in types

Vector2

2D vector type containing x and y fields. Can also be accessed as an array.

Vector2i

Same as a Vector2 but the components are integers. Useful for representing items in a 2D grid.

Rect2

2D Rectangle type containing two vectors fields: position and size. Also contains an end field which is position + size.

Vector3

3D vector type containing x, y and z fields. This can also be accessed as an array.

Vector3i

Same as Vector3 but the components are integers. Can be use for indexing items in a 3D grid.

Transform2D

3×2 matrix used for 2D transforms.

Plane

3D Plane type in normalized form that contains a normal vector field and a d scalar distance.

Quat

Quaternion is a datatype used for representing a 3D rotation. It's useful for interpolating rotations.

AABB

Axis-aligned bounding box (or 3D box) contains 2 vectors fields: position and size. Also contains an end field which is position + size.

Basis

3x3 matrix used for 3D rotation and scale. It contains 3 vector fields (x, y and z) and can also be accessed as an array of 3D vectors.

Transform

3D Transform contains a Basis field basis and a Vector3 field origin.

Engine built-in types

Color

Color data type contains r, g, b, and a fields. It can also be accessed as h, s, and v for hue/saturation/value.

NodePath

Compiled path to a node used mainly in the scene system. It can be easily assigned to, and from, a String.

RID

Resource ID (RID). Servers use generic RIDs to reference opaque data.

Object

Base class for anything that is not a built-in type.

Container built-in types

Array

Generic sequence of arbitrary object types, including other arrays or dictionaries (see below). The array can resize dynamically. Arrays are indexed starting from index 0. Negative indices count from the end.

var arr = []
arr = [1, 2, 3]
var b = arr[1] # This is 2.
var c = arr[arr.size() - 1] # This is 3.
var d = arr[-1] # Same as the previous line, but shorter.
arr[0] = "Hi!" # Replacing value 1 with "Hi!".
arr.append(4) # Array is now ["Hi!", 2, 3, 4].

GDScript arrays are allocated linearly in memory for speed. Large arrays (more than tens of thousands of elements) may however cause memory fragmentation. If this is a concern, special types of arrays are available. These only accept a single data type. They avoid memory fragmentation and use less memory, but are atomic and tend to run slower than generic arrays. They are therefore only recommended to use for large data sets:

Dictionary

Associative container which contains values referenced by unique keys.

var d = {4: 5, "A key": "A value", 28: [1, 2, 3]}
d["Hi!"] = 0
d = {
    22: "value",
    "some_key": 2,
    "other_key": [2, 3, 4],
    "more_key": "Hello"
}

Lua-style table syntax is also supported. Lua-style uses = instead of : and doesn't use quotes to mark string keys (making for slightly less to write). However, keys written in this form can't start with a digit (like any GDScript identifier).

var d = {
    test22 = "value",
    some_key = 2,
    other_key = [2, 3, 4],
    more_key = "Hello"
}

To add a key to an existing dictionary, access it like an existing key and assign to it:

var d = {} # Create an empty Dictionary.
d.waiting = 14 # Add String "waiting" as a key and assign the value 14 to it.
d[4] = "hello" # Add integer 4 as a key and assign the String "hello" as its value.
d["Godot"] = 3.01 # Add String "Godot" as a key and assign the value 3.01 to it.

var test = 4
# Prints "hello" by indexing the dictionary with a dynamic key.
# This is not the same as `d.test`. The bracket syntax equivalent to
# `d.test` is `d["test"]`.
print(d[test])

Note

The bracket syntax can be used to access properties of any Object, not just Dictionaries. Keep in mind it will cause a script error when attempting to index a non-existing property. To avoid this, use the Object.get() and Object.set() methods instead.

Signal

A signal is a message that can be emitted by an object to those who want to listen to it. The Signal type can be used for passing the emitter around.

Signals are better used by getting them from actual objects, e.g. $Button.button_up.

Callable

Contains an object and a function, which is useful for passing functions as values (e.g. when connecting to signals).

Getting a method as a member returns a callable.``var x = $Sprite2D.rotate`` will set the value of x to a callable with $Sprite2D as the object and rotate as the method.

You can call it using the call method: x.call(PI).

Data

Variables

Variables can exist as class members or local to functions. They are created with the var keyword and may, optionally, be assigned a value upon initialization.

var a # Data type is 'null' by default.
var b = 5
var c = 3.8
var d = b + c # Variables are always initialized in order.

Variables can optionally have a type specification. When a type is specified, the variable will be forced to have always that same type, and trying to assign an incompatible value will raise an error.

Types are specified in the variable declaration using a : (colon) symbol after the variable name, followed by the type.

var my_vector2: Vector2
var my_node: Node = Sprite2D.new()

If the variable is initialized within the declaration, the type can be inferred, so it's possible to omit the type name:

var my_vector2 := Vector2() # 'my_vector2' is of type 'Vector2'.
var my_node := Sprite2D.new() # 'my_node' is of type 'Sprite2D'.

Type inference is only possible if the assigned value has a defined type, otherwise it will raise an error.

Valid types are:

  • Built-in types (Array, Vector2, int, String, etc.).

  • Engine classes (Node, Resource, Reference, etc.).

  • Constant names if they contain a script resource (MyScript if you declared const MyScript = preload("res://my_script.gd")).

  • Other classes in the same script, respecting scope (InnerClass.NestedClass if you declared class NestedClass inside the class InnerClass in the same scope).

  • Script classes declared with the class_name keyword.

  • Autoloads registered as singletons.

Casting

Values assigned to typed variables must have a compatible type. If it's needed to coerce a value to be of a certain type, in particular for object types, you can use the casting operator as.

Casting between object types results in the same object if the value is of the same type or a subtype of the cast type.

var my_node2D: Node2D
my_node2D = $Sprite2D as Node2D # Works since Sprite2D is a subtype of Node2D.

If the value is not a subtype, the casting operation will result in a null value.

var my_node2D: Node2D
my_node2D = $Button as Node2D # Results in 'null' since a Button is not a subtype of Node2D.

For built-in types, they will be forcibly converted if possible, otherwise the engine will raise an error.

var my_int: int
my_int = "123" as int # The string can be converted to int.
my_int = Vector2() as int # A Vector2 can't be converted to int, this will cause an error.

Casting is also useful to have better type-safe variables when interacting with the scene tree:

# Will infer the variable to be of type Sprite2D.
var my_sprite := $Character as Sprite2D

# Will fail if $AnimPlayer is not an AnimationPlayer, even if it has the method 'play()'.
($AnimPlayer as AnimationPlayer).play("walk")

Constants

Constants are values you cannot change when the game is running. Their value must be known at compile-time. Using the const keyword allows you to give a constant value a name. Trying to assign a value to a constant after it's declared will give you an error.

We recommend using constants whenever a value is not meant to change.

const A = 5
const B = Vector2(20, 20)
const C = 10 + 20 # Constant expression.
const D = Vector2(20, 30).x # Constant expression: 20.
const E = [1, 2, 3, 4][0] # Constant expression: 1.
const F = sin(20) # 'sin()' can be used in constant expressions.
const G = x + 20 # Invalid; this is not a constant expression!
const H = A + 20 # Constant expression: 25 (`A` is a constant).

Although the type of constants is inferred from the assigned value, it's also possible to add explicit type specification:

const A: int = 5
const B: Vector2 = Vector2()

Assigning a value of an incompatible type will raise an error.

You can also create constants inside a function, which is useful to name local magic values.

Note

Since objects, arrays and dictionaries are passed by reference, constants are "flat". This means that if you declare a constant array or dictionary, it can still be modified afterwards. They can't be reassigned with another value though.

Enums

Enums are basically a shorthand for constants, and are pretty useful if you want to assign consecutive integers to some constant.

If you pass a name to the enum, it will put all the keys inside a constant dictionary of that name.

Important

In Godot 3.1 and later, keys in a named enum are not registered as global constants. They should be accessed prefixed by the enum's name (Name.KEY); see an example below.

enum {TILE_BRICK, TILE_FLOOR, TILE_SPIKE, TILE_TELEPORT}
# Is the same as:
const TILE_BRICK = 0
const TILE_FLOOR = 1
const TILE_SPIKE = 2
const TILE_TELEPORT = 3

enum State {STATE_IDLE, STATE_JUMP = 5, STATE_SHOOT}
# Is the same as:
const State = {STATE_IDLE = 0, STATE_JUMP = 5, STATE_SHOOT = 6}
# Access values with State.STATE_IDLE, etc.

Functions

Functions always belong to a class. The scope priority for variable look-up is: local → class member → global. The self variable is always available and is provided as an option for accessing class members, but is not always required (and should not be sent as the function's first argument, unlike Python).

func my_function(a, b):
    print(a)
    print(b)
    return a + b  # Return is optional; without it 'null' is returned.

A function can return at any point. The default return value is null.

Functions can also have type specification for the arguments and for the return value. Types for arguments can be added in a similar way to variables:

func my_function(a: int, b: String):
    pass

If a function argument has a default value, it's possible to infer the type:

func my_function(int_arg := 42, String_arg := "string"):
    pass

The return type of the function can be specified after the arguments list using the arrow token (->):

func my_int_function() -> int:
    return 0

Functions that have a return type must return a proper value. Setting the type as void means the function doesn't return anything. Void functions can return early with the return keyword, but they can't return any value.

func void_function() -> void:
    return # Can't return a value.

Note

Non-void functions must always return a value, so if your code has branching statements (such as an if/else construct), all the possible paths must have a return. E.g., if you have a return inside an if block but not after it, the editor will raise an error because if the block is not executed, the function won't have a valid value to return.

Referencing functions

Functions are first-class items in terms of the Callable object. Referencing a function by name without calling it will automatically generate the proper callable. This can be used to pass functions as arguments.

func map(arr: Array, function: Callable) -> Array:
    var result = []
    for item in arr:
        result.push_back(function.call(item))
    return result

func add1(value: int) -> int:
    return value + 1;

func _ready() -> void:
    var my_array = [1, 2, 3]
    var plus_one = map(my_array, add1)
    print(plus_one) # Prints [2, 3, 4].

Note

Callables must be called with the call method. You cannot use the () operator directly. This behavior is implemented to avoid performance issues on direct function calls.

Static functions

A function can be declared static. When a function is static, it has no access to the instance member variables or self. This is mainly useful to make libraries of helper functions:

static func sum2(a, b):
    return a + b

Statements and control flow

Statements are standard and can be assignments, function calls, control flow structures, etc (see below). ; as a statement separator is entirely optional.

Expressions

Expressions are sequences of operators and their operands in orderly fashion. An expression by itself can be a statement too, though only calls are reasonable to use as statements since other expressions don't have side effects.

Expressions return values that can be assigned to valid targets. Operands to some operator can be another expression. An assignment is not an expression and thus does not return any value.

Here are some examples of expressions:

2 + 2 # Binary operation.
-5 # Unary operation.
"okay" if x > 4 else "not okay" # Ternary operation.
x # Identifier representing variable or constant.
x.a # Attribute access.
x[4] # Subscript access.
x > 2 or x < 5 # Comparisons and logic operators.
x == y + 2 # Equality test.
do_something() # Function call.
[1, 2, 3] # Array definition.
{A = 1, B = 2} # Dictionary definition.
preload("res://icon.png) # Preload builtin function.
self # Reference to current instance.

Identifiers, attributes, and subscripts are valid assignment targets. Other expressions cannot be on the left side of an assignment.

if/else/elif

Simple conditions are created by using the if/else/elif syntax. Parenthesis around conditions are allowed, but not required. Given the nature of the tab-based indentation, elif can be used instead of else/if to maintain a level of indentation.

if [expression]:
    statement(s)
elif [expression]:
    statement(s)
else:
    statement(s)

Short statements can be written on the same line as the condition:

if 1 + 1 == 2: return 2 + 2
else:
    var x = 3 + 3
    return x

Sometimes, you might want to assign a different initial value based on a boolean expression. In this case, ternary-if expressions come in handy:

var x = [value] if [expression] else [value]
y += 3 if y < 10 else -1

Ternary-if expressions can be nested to handle more than 2 cases. When nesting ternary-if expressions, it is recommended to wrap the complete expression over multiple lines to preserve readability:

var count = 0

var fruit = (
        "apple" if count == 2
        else "pear" if count == 1
        else "banana" if count == 0
        else "orange"
)
print(fruit)  # banana

# Alternative syntax with backslashes instead of parentheses (for multi-line expressions).
# Less lines required, but harder to refactor.
var fruit_alt = \
        "apple" if count == 2 \
        else "pear" if count == 1 \
        else "banana" if count == 0 \
        else "orange"
print(fruit_alt)  # banana

while

Simple loops are created by using while syntax. Loops can be broken using break or continued using continue:

while [expression]:
    statement(s)

for

To iterate through a range, such as an array or table, a for loop is used. When iterating over an array, the current array element is stored in the loop variable. When iterating over a dictionary, the key is stored in the loop variable.

for x in [5, 7, 11]:
    statement # Loop iterates 3 times with 'x' as 5, then 7 and finally 11.

var dict = {"a": 0, "b": 1, "c": 2}
for i in dict:
    print(dict[i]) # Prints 0, then 1, then 2.

for i in range(3):
    statement # Similar to [0, 1, 2] but does not allocate an array.

for i in range(1, 3):
    statement # Similar to [1, 2] but does not allocate an array.

for i in range(2, 8, 2):
    statement # Similar to [2, 4, 6] but does not allocate an array.

for c in "Hello":
    print(c) # Iterate through all characters in a String, print every letter on new line.

for i in 3:
    statement # Similar to range(3).

for i in 2.2:
    statement # Similar to range(ceil(2.2)).

match

A match statement is used to branch execution of a program. It's the equivalent of the switch statement found in many other languages, but offers some additional features.

Basic syntax:

match [expression]:
    [pattern](s):
        [block]
    [pattern](s):
        [block]
    [pattern](s):
        [block]

Crash-course for people who are familiar with switch statements:

  1. Replace switch with match.

  2. Remove case.

  3. Remove any breaks.

  4. Change default to a single underscore.

Control flow:

The patterns are matched from top to bottom. If a pattern matches, the first corresponding block will be executed. After that, the execution continues below the match statement. You can use continue to stop execution in the current block and check for an additional match in the patterns below it.

There are 6 pattern types:

  • Constant pattern

    Constant primitives, like numbers and strings:

    match x:
        1:
            print("We are number one!")
        2:
            print("Two are better than one!")
        "test":
            print("Oh snap! It's a string!")
    
  • Variable pattern

    Matches the contents of a variable/enum:

    match typeof(x):
        TYPE_REAL:
            print("float")
        TYPE_STRING:
            print("text")
        TYPE_ARRAY:
            print("array")
    
  • Wildcard pattern

    This pattern matches everything. It's written as a single underscore.

    It can be used as the equivalent of the default in a switch statement in other languages:

    match x:
        1:
            print("It's one!")
        2:
            print("It's one times two!")
        _:
            print("It's not 1 or 2. I don't care to be honest.")
    
  • Binding pattern

    A binding pattern introduces a new variable. Like the wildcard pattern, it matches everything - and also gives that value a name. It's especially useful in array and dictionary patterns:

    match x:
        1:
            print("It's one!")
        2:
            print("It's one times two!")
        var new_var:
            print("It's not 1 or 2, it's ", new_var)
    
  • Array pattern

    Matches an array. Every single element of the array pattern is a pattern itself, so you can nest them.

    The length of the array is tested first, it has to be the same size as the pattern, otherwise the pattern doesn't match.

    Open-ended array: An array can be bigger than the pattern by making the last subpattern ...

    Every subpattern has to be comma-separated.

    match x:
        []:
            print("Empty array")
        [1, 3, "test", null]:
            print("Very specific array")
        [var start, _, "test"]:
            print("First element is ", start, ", and the last is \"test\"")
        [42, ..]:
            print("Open ended array")
    
  • Dictionary pattern

    Works in the same way as the array pattern. Every key has to be a constant pattern.

    The size of the dictionary is tested first, it has to be the same size as the pattern, otherwise the pattern doesn't match.

    Open-ended dictionary: A dictionary can be bigger than the pattern by making the last subpattern ...

    Every subpattern has to be comma separated.

    If you don't specify a value, then only the existence of the key is checked.

    A value pattern is separated from the key pattern with a :.

    match x:
        {}:
            print("Empty dict")
        {"name": "Dennis"}:
            print("The name is Dennis")
        {"name": "Dennis", "age": var age}:
            print("Dennis is ", age, " years old.")
        {"name", "age"}:
            print("Has a name and an age, but it's not Dennis :(")
        {"key": "godotisawesome", ..}:
            print("I only checked for one entry and ignored the rest")
    
  • Multiple patterns

    You can also specify multiple patterns separated by a comma. These patterns aren't allowed to have any bindings in them.

    match x:
        1, 2, 3:
            print("It's 1 - 3")
        "Sword", "Splash potion", "Fist":
            print("Yep, you've taken damage")
    

Classes

By default, all script files are unnamed classes. In this case, you can only reference them using the file's path, using either a relative or an absolute path. For example, if you name a script file character.gd:

# Inherit from 'Character.gd'.

extends "res://path/to/character.gd"

# Load character.gd and create a new node instance from it.

var Character = load("res://path/to/character.gd")
var character_node = Character.new()

Registering named classes

You can give your class a name to register it as a new type in Godot's editor. For that, you use the class_name keyword. You can optionally use the @icon annotation with a path to an image, to use it as an icon. Your class will then appear with its new icon in the editor:

# Item.gd

extends Node
class_name Item
@icon("res://interface/icons/item.png")
../../../_images/class_name_editor_register_example.png

Here's a class file example:

# Saved as a file named 'character.gd'.

class_name Character


var health = 5


func print_health():
    print(health)


func print_this_script_three_times():
    print(get_script())
    print(ResourceLoader.load("res://character.gd"))
    print(Character)

If you want to use extends too, you can keep both on the same line:

class_name MyNode extends Node

Note

Godot's class syntax is compact: it can only contain member variables or functions. You can use static functions, but not static member variables. In the same way, the engine initializes variables every time you create an instance, and this includes arrays and dictionaries. This is in the spirit of thread safety, since scripts can be initialized in separate threads without the user knowing.

Inheritance

A class (stored as a file) can inherit from:

  • A global class.

  • Another class file.

  • An inner class inside another class file.

Multiple inheritance is not allowed.

Inheritance uses the extends keyword:

# Inherit/extend a globally available class.
extends SomeClass

# Inherit/extend a named class file.
extends "somefile.gd"

# Inherit/extend an inner class in another file.
extends "somefile.gd".SomeInnerClass

To check if a given instance inherits from a given class, the is keyword can be used:

# Cache the enemy class.
const Enemy = preload("enemy.gd")

# [...]

# Use 'is' to check inheritance.
if entity is Enemy:
    entity.apply_damage()

To call a function in a super class (i.e. one extend-ed in your current class), user the super keyword:

super(args)

This is especially useful because functions in extending classes replace functions with the same name in their super classes. If you still want to call them, you can use super:

func some_func(x):
    super(x) # Calls the same function on the super class.

If you need to call a different function from the super class, you can specify the function name with the attribute operator:

func overriding():
    return 0 # This overrides the method in the base class.

func dont_override():
    return super.overriding() # This calls the method as defined in the base class.

Class constructor

The class constructor, called on class instantiation, is named _init. If you want to call the base class constructor, you can also use the super syntax. Note that every class has an implicit constructor that it's always called (defining the default values of class variables). super is used to call the explicit constructor:

func _init(arg):
   super("some_default", arg) # Call the custom base constructor.

This is better explained through examples. Consider this scenario:

# State.gd (inherited class).
var entity = null
var message = null


func _init(e=null):
    entity = e


func enter(m):
    message = m


# Idle.gd (inheriting class).
extends "State.gd"


func _init(e=null, m=null):
    super(e)
    # Do something with 'e'.
    message = m

There are a few things to keep in mind here:

  1. If the inherited class (State.gd) defines a _init constructor that takes arguments (e in this case), then the inheriting class (Idle.gd) must define _init as well and pass appropriate parameters to _init from State.gd.

  2. Idle.gd can have a different number of arguments than the base class State.gd.

  3. In the example above, e passed to the State.gd constructor is the same e passed in to Idle.gd.

  4. If Idle.gd's _init constructor takes 0 arguments, it still needs to pass some value to the State.gd base class, even if it does nothing. This brings us to the fact that you can pass expressions to the base constructor as well, not just variables, e.g.:

    # Idle.gd
    
    func _init():
        super(5)
    

Inner classes

A class file can contain inner classes. Inner classes are defined using the class keyword. They are instanced using the ClassName.new() function.

# Inside a class file.

# An inner class in this class file.
class SomeInnerClass:
    var a = 5


    func print_value_of_a():
        print(a)


# This is the constructor of the class file's main class.
func _init():
    var c = SomeInnerClass.new()
    c.print_value_of_a()

Classes as resources

Classes stored as files are treated as resources. They must be loaded from disk to access them in other classes. This is done using either the load or preload functions (see below). Instancing of a loaded class resource is done by calling the new function on the class object:

# Load the class resource when calling load().
var MyClass = load("myclass.gd")

# Preload the class only once at compile time.
const MyClass = preload("myclass.gd")


func _init():
    var a = MyClass.new()
    a.some_function()

Exports

Note

Documentation about exports has been moved to GDScript exports.

Properties

Sometimes you want a class' member variable to do more than just hold data and actually perform some validation or computation whenever its value change. It may also be desired to encapsulate its access in some way.

For this, GDScript provides a special syntax to define properties using the set and get keywords after a variable declaration. Then you can define a code block that will be executed when the variable is accessed or assigned.

Example:

var milliseconds: int = 0
var seconds: int:
    get:
        return milliseconds / 1000
    set(value):
        milliseconds = value * 1000

Using the variable name inside its own setter or getter will directly access the underlying member, so it won't generate infinite recursion and saves you from explicitly declaring another variable:

signal changed(new_value)
var warns_when_changed = "some value":
    get:
        return warns_when_changed
    set(value):
        changed.emit(value)
        warns_when_changed = value

This backing member variable is not created if you don't use it.

Note

Unlike setget in previous Godot versions, the properties setter and getter are always called, even when accessed inside the same class (with or without prefixing with self.). This makes the behavior consistent. If you need direct access to the value, use another variable for direct access and make the property code use that name.

In case you want to split the code from the variable declaration or you need to share the code across multiple properties, you can use a different notation to use existing class functions:

var my_prop:
    get = get_my_prop, set = set_my_prop

This can also be done in the same line.

Tool mode

By default, scripts don't run inside the editor and only the exported properties can be changed. In some cases, it is desired that they do run inside the editor (as long as they don't execute game code or manually avoid doing so). For this, the @tool annotation exists and must be placed at the top of the file:

@tool
extends Button

func _ready():
    print("Hello")

See Running code in the editor for more information.

Warning

Be cautious when freeing nodes with queue_free() or free() in a tool script (especially the script's owner itself). As tool scripts run their code in the editor, misusing them may lead to crashing the editor.

Memory management

If a class inherits from class_Reference, then instances will be freed when no longer in use. No garbage collector exists, just reference counting. By default, all classes that don't define inheritance extend Reference. If this is not desired, then a class must inherit Object manually and must call instance.free(). To avoid reference cycles that can't be freed, a WeakRef function is provided for creating weak references. Here is an example:

extends Node

var my_node_ref

func _ready():
    my_node_ref = weakref(get_node("MyNode"))

func _this_is_called_later():
    var my_node = my_node_ref.get_ref()
    if my_node:
        my_node.do_something()

Alternatively, when not using references, the is_instance_valid(instance) can be used to check if an object has been freed.

Signals

Signals are a tool to emit messages from an object that other objects can react to. To create custom signals for a class, use the signal keyword.

extends Node


# A signal named health_depleted.
signal health_depleted

Note

Signals are a Callback mechanism. They also fill the role of Observers, a common programming pattern. For more information, read the Observer tutorial in the Game Programming Patterns ebook.

You can connect these signals to methods the same way you connect built-in signals of nodes like Button or class_RigidBody.

In the example below, we connect the health_depleted signal from a Character node to a Game node. When the Character node emits the signal, the game node's _on_Character_health_depleted is called:

# Game.gd

func _ready():
    var character_node = get_node('Character')
    character_node.health_depleted.connect(_on_Character_health_depleted)


func _on_Character_health_depleted():
    get_tree().reload_current_scene()

You can emit as many arguments as you want along with a signal.

Here is an example where this is useful. Let's say we want a life bar on screen to react to health changes with an animation, but we want to keep the user interface separate from the player in our scene tree.

In our Character.gd script, we define a health_changed signal and emit it with Signal.emit(), and from a Game node higher up our scene tree, we connect it to the Lifebar using the Signal.connect() method:

# Character.gd

...
signal health_changed


func take_damage(amount):
    var old_health = health
    health -= amount

    # We emit the health_changed signal every time the
    # character takes damage.
    health_changed.emit(old_health, health)
...
# Lifebar.gd

# Here, we define a function to use as a callback when the
# character's health_changed signal is emitted.

...
func _on_Character_health_changed(old_value, new_value):
    if old_value > new_value:
        progress_bar.modulate = Color.red
    else:
        progress_bar.modulate = Color.green

    # Imagine that `animate` is a user-defined function that animates the
    # bar filling up or emptying itself.
    progress_bar.animate(old_value, new_value)
...

In the Game node, we get both the Character and Lifebar nodes, then connect the character, that emits the signal, to the receiver, the Lifebar node in this case.

# Game.gd

func _ready():
    var character_node = get_node('Character')
    var lifebar_node = get_node('UserInterface/Lifebar')

    character_node.health_changed.connect(lifebar_node._on_Character_health_changed)

This allows the Lifebar to react to health changes without coupling it to the Character node.

You can write optional argument names in parentheses after the signal's definition:

# Defining a signal that forwards two arguments.
signal health_changed(old_value, new_value)

These arguments show up in the editor's node dock, and Godot can use them to generate callback functions for you. However, you can still emit any number of arguments when you emit signals; it's up to you to emit the correct values.

../../../_images/gdscript_basics_signals_node_tab_1.png

GDScript can bind an array of values to connections between a signal and a method. When the signal is emitted, the callback method receives the bound values. These bound arguments are unique to each connection, and the values will stay the same.

You can use this array of values to add extra constant information to the connection if the emitted signal itself doesn't give you access to all the data that you need.

Building on the example above, let's say we want to display a log of the damage taken by each character on the screen, like Player1 took 22 damage.. The health_changed signal doesn't give us the name of the character that took damage. So when we connect the signal to the in-game console, we can add the character's name in the binds array argument:

# Game.gd

func _ready():
    var character_node = get_node('Character')
    var battle_log_node = get_node('UserInterface/BattleLog')

    character_node.health_changed.connect(battle_log_node._on_Character_health_changed, [character_node.name])

Our BattleLog node receives each element in the binds array as an extra argument:

# BattleLog.gd

func _on_Character_health_changed(old_value, new_value, character_name):
    if not new_value <= old_value:
        return

    var damage = old_value - new_value
    label.text += character_name + " took " + str(damage) + " damage."

Awaiting for signals

The await keyword can be used to create coroutines which waits until a signal is emitted before continuing execution. Using the await keyword with a signal or a call to a function that is also a coroutine will immediately return the control to the caller. When the signal is emitted (or the called coroutine finishes), it will resume execution from the point on where it stopped.

For example, to stop execution until the user presses a button, you can do something like this:

func wait_confirmation():
    print("Prompting user")
    await $Button.button_up # Waits for the button_up signal from Button node.
    print("User confirmed")
    return true

In this case, the wait_confirmation becomes a coroutine, which means that the caller also needs to await for it:

func request_confirmation():
    print("Will ask the user")
    var confirmed = await wait_confirmation()
    if confirmed:
        print("User confirmed")
    else:
        print("User cancelled")

Note that requesting a coroutine's return value without await will trigger an error:

func wrong():
    var confirmed = wait_confirmation() # Will give an error.

However, if you don't depend on the result, you can just call it asynchronously, which won't stop execution and won't make the current function a coroutine:

func okay():
    wait_confirmation()
    print("This will be printed immediately, before the user press the button.")

If you use await with an expression that isn't a signal nor a coroutine, the value will be returned immediately and the function won't give the control back to the caller:

func no_wait():
    var x = await get_five()
    print("This doesn't make this function a coroutine.")

func get_five():
    return 5

This also means that returning a signal from a function that isn't a coroutine will make the caller await on that signal:

func get_signal():
    return $Button.button_up

func wait_button():
    await get_signal()
    print("Button was pressed")

Note

Unlike yield in previous Godot versions, you cannot obtain the function state object. This in spirit of type-safety, because a function cannot say that returns an int but actually give a function state object during runtime.

@onready annotation

When using nodes, it's common to desire to keep references to parts of the scene in a variable. As scenes are only warranted to be configured when entering the active scene tree, the sub-nodes can only be obtained when a call to Node._ready() is made.

var my_label


func _ready():
    my_label = get_node("MyLabel")

This can get a little cumbersome, especially when nodes and external references pile up. For this, GDScript has the @onready annotation, that defers initialization of a member variable until _ready() is called. It can replace the above code with a single line:

@onready var my_label = get_node("MyLabel")

Assert keyword

The assert keyword can be used to check conditions in debug builds. These assertions are ignored in non-debug builds.