Range Over Iterators in GDScript

With the provided input, the task is to translate the Go code example into GDScript. Here is how the code and explanation will look in Markdown format suitable for Hugo:

Starting with Godot version 3.2, GDScript has added support for iterators using the for loop, which lets us range over pretty much anything!

extends Node

class List:
    var head: Element = null
    var tail: Element = null

    class Element:
        var next: Element = null
        var val: Variant = null

    func push(val: Variant) -> void:
        if tail == null:
            head = Element.new()
            head.val = val
            tail = head
        else:
            tail.next = Element.new()
            tail.next.val = val
            tail = tail.next

    func all() -> Iterator:
        return Iterator.new(self)

    class Iterator:
        var list: List
        var current: Element

        func _init(list: List) -> void:
            self.list = list
            self.current = list.head

        func has_next() -> bool:
            return self.current != null

        func next() -> Variant:
            val = self.current.val
            self.current = self.current.next
            return val

func _ready():
    var lst = List.new()
    lst.push(10)
    lst.push(13)
    lst.push(23)

    for val in lst.all():
        print(val)

# To iterate over Fibonacci numbers:
class Fibonacci:
    var a: int = 1
    var b: int = 1

    func all() -> Iterator:
        return Iterator.new(self)

    class Iterator:
        var fibonacci: Fibonacci

        func _init(fibonacci: Fibonacci) -> void:
            self.fibonacci = fibonacci

        func has_next() -> bool:
            return true

        func next() -> int:
            var a = self.fibonacci.a
            var b = self.fibonacci.b
            self.fibonacci.a = b
            self.fibonacci.b = a + b
            return a

func _ready():
    var fib = Fibonacci.new()
    for n in fib.all():
        if n >= 10:
            break
        print(n)

GDScript’s for loop ranges over iterators using the next() method to get the next element until has_next() returns false. We implemented the List class with a nested Element and Iterator class to handle iteration and the push method to add elements to the list.

The Fibonacci class generates an infinite sequence of Fibonacci numbers as long as the for loop continues. This is illustrated with a break statement when the current number equals or exceeds 10.

To run this code, attach it to a Node in your Godot scene and run the scene.

By leveraging GDScript’s support for iterators, we can elegantly iterate over custom data structures like lists or even infinite sequences like Fibonacci numbers. This makes GDScript both powerful and expressive for game development in Godot.

Generics in GDScript

Errors in GDScript

Learn X By Example

Title here

Range Over Iterators in GDScript