queue_call_deferred() method

[pixel-boy]

When I create tools, I often have methods to generate or update nodes:

func update():
	# Updates the nodes


func generate():
	# Generate all the necessary nodes

And to prevent these functions from being called multiple times in the same frame, I have method queue_update() and queue_generate(), currently, the simplest version I've found to do this is to write this:

func queue_update():
	if !RenderingServer.frame_pre_draw.is_connected(update):
	RenderingServer.frame_pre_draw.connect(update,CONNECT_ONE_SHOT)

I wanted to know if there was a shorter / more optimal way, and if not I would like to suggest adding a method, I'm not sure what form it should take, maybe something like a call_deferred variant:

update.queue_call_deferred()

[sockeye-d]

I wouldn't use frane_pre_draw here, since SceneTree.process_frame exists and frames are not guaranteed to be drawn for every process tick (for example, if you have low processor mode on).

I will add that I do think this is a fairly common pattern and it'd be cool if Callable got some sort of mechanism for it, although in my opinion it should be called queue_call, like queue_redraw and queue_update. Logistically though, where would it get tracked? A global hash map would be slow and unwieldy, and storing it on the Callable itself would have inconsistent semantics. Also, since (as far as I know) Callables aren't interned, so it'd have unintuitive behavior when doing something like

func do_stuff() -> void:
    (func(): print("hi")).queue_call()

which would end up printing once for every call rather than once per frame