Godot 4 await parallel calls

MultiAwait.gd

extends RefCounted
class_name MultiAwaiter
## Can await till multiple method calls are done
## 
## You use it like:
## [codeblock]
## var awaiter = MultipleAwait.new()
## awaiter.push_method( my_func.bind(arg_a, arg_b, ...) ) 
## await awaiter.run()  # You can also connect stuff to it's completed signal
## [/codeblock]
##
## It's probably not a good idea to reuse it, so no method to clear the method_list is provided


signal completed

var _remaining : int = 0
var _method_list : Array[Callable] = []

## Used to build your list of methos to call. Use method_name.bind() to call with arguments
func push_method(method: Callable):
	_method_list.append(method)


## Corroutine that calls all the methods in parallel and waits till they are done
func run():
	assert( _remaining == 0, "Either you tried to call run() while it was already running or it's a bug")
	_remaining = _method_list.size()
	for m in _method_list:
		(func(): await m.call(); _on_method_done() ).call()
	# If _remaining is 0 either we had an empty _method_list or all the methods completed immediately
	if _remaining == 0:
		completed.emit() # not needed internally but there might be external connections
		return
	# otherwise await the completed signal
	await completed

## Internal. Updates remaining count and emits the completed signal when it reaches 0
func _on_method_done():
	_remaining -= 1
	assert(_remaining >= 0)
	if _remaining == 0:
		completed.emit()