How to make a class "printable"?

Question

I am looking for something similar to toString method in Scala or show typeclass from Haskell. Example:

extends Node

class C:
    var x
    func _init(nx = 0):
        x = nx

func _ready():
    print(C.new(4))

Output:

[Reference:978]

Example of desired output (defined in class):

C(4)

---

Is there some standard way of doing this in GDScript*, or adhoc method is only solution?

---

*: For example a method which gets called by print (I failed to find documentation for print, the search in docs is a bit weird).

Answer 1

Add the function _to_string() to your class

class C:
    var x
    func _init(nx = 0):
        x = nx

    func _to_string():
        return "C(%s)" % x

func _ready():
    print(C.new(4))

Output :

C(4)

I found the answer in this discussion : https://github.com/godotengine/godot/pull/27886

Answer 2

Unless this has since changed, it doesn't seem like this is possible yet:

• https://github.com/godotengine/godot/pull/6306
• https://www.reddit.com/r/godot/comments/al7zub/is_there_an_equivalent_to_pythons_def_str_self_in/
• https://github.com/godotengine/godot/issues/2085

As an alternative, you could write your own utility singleton that handles it

extends Node
class_name Utils

static func print(obj):
    match typeof(obj):
         typeof(SomeClass):
               print(obj.property, obj.property, ...)

Then you can call it like:

Utils.print(some_object)

Answer 3

An obvious alternative is simply add a to_string() function, no need for a singleton:

class C:
    var x
    func _init(nx = 0):
        x = nx

    func to_string():
        return 'C(%s)' % x

func _ready():
    print(C.new(4).to_string())

Output:

C(4)