Is variable arguments supported in gdscript?

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:information_source: Attention Topic was automatically imported from the old Question2Answer platform.
:bust_in_silhouette: Asked By alexzheng

I want to define a method with variable arguments, is that supported?

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:bust_in_silhouette: Reply From: Zaven Muradyan

Unfortunately, it doesn’t appear that this is supported yet: GDScript: Variadic functions (variable number of arguments/varargs) · Issue #16565 · godotengine/godot · GitHub

The basic workaround would be to accept an array argument and just use array notation at the call site:

func foo(args):
    for x in args:
        pass

foo(["hello", "world"])
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:bust_in_silhouette: Reply From: jagc

This is a duplicate of this question.
The answer provided there hits it perfectly.

For those too lazy to click the link, this is one example variation of implementing the answer:

func nameOfFunc(firstArg, params = {}):
  var data = firstArg

  # Ternary operation just to keep it short
  # But you can do whatever you want when:
  #   checking a key's existence and assigning values
  var a = (0 if not params.has('a') else params['a'])
  var b = (0 if not params.has('b') else params['b'])
  var c = (0 if not params.has('c') else params['c'])

  data += a + b + c

  return data

So let’s call it inside a function.

func printExample():
  var a = 1
  var c = 1

  # in our definition, we have named optional parameters 'a', 'b', 'c'
  # we're only setting up to use 'a' and 'c'
  
  var params = {
    a = a,
    c = c
	}

  var sum = nameOfFunc(1, params)

  print(sum) # output: 3

Tested working at Godot 3.1.1

Old thread, but in case someone else stumbles on this like I did, I want to add two points:

  1. Since dictionaries are mutable, using them as a default param value is dangerous. Any changes to the params dict in the method would persist across method calls, causing unwanted behavior.
  2. You can simplify the code for getting the params by using dictionary’s built-in .get() method instead of using inline if statements.

With the above two considerations, here’s what I’d do for arbitrary parameters:

func nameOfFunc(firstArg, params = null):
var data = firstArg

if params != null:
    var a = params.get('a', 0)
    var b = params.get('b', 0)
    var c = params.get('c', 0)

    data += a + b + c

return data

BigOzzie | 2022-10-02 17:53

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I posted about a kwargs unpacker function I made, if anyone is interested. I dont know if it can be used for all situations, but you can try it and edit it as needed/wanted.

Hope it helps someone

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Stumbled upon this in a Google search pretty easily so I’m just going to add (8 years later lol) variadic arguments have been supported since 4.5.

Usage:

Func my_variadic_function(example: int, param: string, … args: Array)

for Arg in args:

Print(Arg)

The docs go over it, but it must be assigned as an untyped Array, must be the last argument in the parameters, and any index can hold any variant value. It’s pretty cool.

Cheers!

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You could link the Docs too :slight_smile:
For anyone interested: Variadic functions on Godot Docs.
It was implemented with PR#82808.

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