Promise.all for Godot 4

Promise.all.gd

class_name Promise
extends Resource

signal completed(results)

var _funcs: Array[Callable]
var _completed := false
var _results: Dictionary


func _init(funcs: Array[Callable]):
	_funcs = funcs
	for idx in range(len(_funcs)):
		_call_func(_funcs[idx], idx)
	

func _call_func(f: Callable, idx: int) -> void:
	var result = await f.call()
	_funcs.erase(f)
	_results[idx] = result

	if _funcs.is_empty() and not _completed:
		var keys = _results.keys()
		keys.sort()

		var to_emit = []
		for i in keys:
			to_emit.append(_results[i])

		completed.emit(to_emit)
		_completed = true