Initialize typed arrays with non trivial types

Help
,
1

Godot Version

Godot_v4.4.1-stable_win64.exe

Question

I’ve read here and here about how to initialize typed arrays.
However, i’m struggling to do this for instances of a specific class, like

extends Node
class_name Pics
class Pic:
	var name : String
	static func create(name : String) -> Pic:
		var instance = Pic.new()
		instance.name = name
		return instance
@export var pics : Array[Pics.Pic] = [ Pic.create("asdf"), ] # Error: Trying to assign an array of type "Array" to a variable of type "Array[Pic]".

Is there a way to do this?

2

Using type casting seemed to eliminate the error, at least for me. Instead of @export var pics : Array[Pics.Pic] = [ Pic.create("asdf"), ], try @export var pics := [ Pic.create("asdf"), ] as Array[Pics.Pic].
See GDScript reference - Casting and Static typing in GDScript - Type casting.

2 Likes
4

Not sure what i’m doing wrong.
Now i get

Export type can only be built-in, a resource, a node, or an enum.

for

@export var pics := [ Pic.create("asdf"), ] as Array[Pics.Pic]

and

@export var pics : Array[Pics.Pic] = [ Pic.create("asdf"), ] as Array[Pics.Pic]

and

@export var pics : Array[Pics.Pic] = [ Pic.create("asdf"), ]

Without @export there are no errors.
I can’t seem to reproduce the old error

Trying to assign an array of type “Array” to a variable of type “Array[Pic]”

but

Export type can only be built-in, a resource, a node, or an enum.

makes it clear and i found a post which talks about this already.

Thanks for your help!

5

Export type can only be built-in, a resource, a node, or an enum.

This is because Pic currently is a class, but not one that inherits from Resource. You can fix this by making the Pic class extend Resource or another class that inherits from it.

extends Node
class_name Pics
class Pic:
    extends Resource
	var name : String
	static func create(name : String) -> Pic:
		var instance = Pic.new()
		instance.name = name
		return instance
@export var pics := [ Pic.create("asdf"), ] as Array[Pics.Pic]
1 Like
6

Thanks for the explanation.

I found that (maybe it changed?) Resource derives from RefCounted.
By deriving Pic from Resource, @export pics as typed array works.

@export var pics : Array[Pics.Pic] = [ Pic.create("asdf"), ]

Thanks a lot!

1 Like
7

My mistake, you’re correct.
I’m glad I could help!