Table of Contents

• Overview of GDScript
• Signals
• Coroutines with yield
• Inheritance
• Define virtual methods
• GDScript file naming convention?
• match

Overview of GDScript tutorial

# A file is a class!

# Inheritance

extends BaseClass

# Member Variables

var a = 5
var s = "Hello"
var arr = [1, 2, 3]
var dict = {"key": "value", 2:3}

# 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)

# Function

func some_function(param1, param2):
    var local_var = 5

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

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

    while param2 != 0:
        param2 -= 1

    var local_var2 = param1 + 3
    return local_var2

# Functions override functions with the same name on the base/parent class.
# If you still want to call them, use '.' (like 'super' in other languages).

func something(p1, p2):
    .something(p1, p2)

# Inner Class

class Something:
    var a = 10

# Constructor

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

Signals discussion

# No arguments.
signal your_signal_name
# With arguments.
signal your_signal_name_with_args(a, b)

func _callback_no_args():
    print("Got callback!")

func _callback_args(a,b):
    print("Got callback with args! a: ", a, " and b: ", b)

func connect_signals():
    instance.connect("your_signal_name", self, "_callback_no_args")
    instance.connect("your_signal_name_with_args", self, "_callback_args")
    # bind arguments to a signal that lacks them
    instance.connect("your_signal_name", self, "_callback_args", [22, "hello"])

func emit_signals():
    emit_signal("your_signal_name")
    emit_signal("your_signal_name_with_args", 55, 128)
    some_instance.emit_signal("some_signal")

Coroutines with yield discussion

func my_func():
   print("Hello")
   yield()
   print("world")

func _ready():
    var y = my_func()
    # Function state saved in 'y'.
    print("my dear")
    y.resume()
    # 'y' resumed and is now an invalid state.

func my_func():
   print("Hello")
   print(yield())
   return "cheers!"

func _ready():
    # `y` is just a GDScriptFunctionState instance.
    # There appears no way to get values from the coroutine
    # with intermediate return value.
    var y = my_func()

    # Function state saved in 'y'.
    print(y.resume("world"))
    # 'y' resumed and is now an invalid state.

func my_func():
        yield(button_func(), "completed")
        print("All buttons were pressed, hurray!")

func button_func():
    yield($Button0, "pressed")
    yield($Button1, "pressed")

Inheritance discussion

# 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

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

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

Define virtual methods howto

• There appears nothing called virtual method, but you can only override methods.
• So, if you want a pure virtual method, you can just define the method signature with pass.

GDScript file naming convention? discussion

• The popular vote seems to be lower snake_case for the actual file name.
• Like player.gd instead of Player.gd
• This is because most of OS-compatibility.

match reference

# constant
match x:
    1:
        print("We are number one!")
    2:
        print("Two are better than one!")
    3, 4, 5:
        print("Three or four or five!")
    "test":
        print("Oh snap! It's a string!")
    _:
        print("Default")

• You can also use binding pattern, array pattern, dictionary pattern.