Signal and Connect

Odin

Hi everybody! I have successfully done several cases of emitt signal and connect. But I have a problem as for example: World's script:

func _ready():
	var abc = get_tree().get_root().find_node("menu",true,false)
	abc.connect("open" ,self, "do_something")

Menu's script:

	
signal open

func _ready():
	emit_signal("open")

In this case, because the Menu node has not been initialized, only when a button is pressed or do something, the Menu node will be initialized. So Godot will give an error "Connect null instance..."So in this case, how do I code to solve this problem? I always have this situation and don't know how to fix it. Want to connect to a node that does not exist.Hope you can guide me.I'm new to coding. Thank you so much.

DaveTheCoder

My solution is to place the connect() in the ready() method of a node that's a common parent of both nodes. By "both nodes", I mean the node that's connecting ("abc" in your example) and the node with the signal handler ("self" in your example). That ensures that both nodes are in the scene tree when the connect() is executed.

Odin

What you say is not possible, because the World node is already the parent of all the nodes in the game. There's no such thing as the father of the World node anymore. Maybe you don't understand what I mean. In case you want to make a connection with a Menu node, that Menu node has not been initialized, as I mentioned above. How will you code then? So that when connect signal it will not give error as " connect null instance.." The above code is only correct when the Menu node is available in the World node. But if the Menu node initializes later, then Godot will give an error immediately. So what should you do in this situation? Someone help me.

duane

If the menu node is created later, have the menu node make the connection.

fire7side

You could maybe connect it with the editor instead. Just declare the signal open and it will show up in the node window for connection.

DaveTheCoder

the World node is already the parent of all the nodes in the game

If that's true, then there should be no problem with connect(). The parent is initialized (added to the scene tree and _ready method called) after its children. What's the complete error message, and are there any other errors?

Is Menu a permanent part of the scene or is it added later? That wasn't clear from your post.

Also, calling emit_signal() from ready() can be tricky. In this case, you're calling emit_signal() from Menu's ready() method, but the node World that contains the "do_something" signal handler hasn't been added to the scene tree yet. You may need to use call_deferred() or yield() to solve that.

Odin

I mean if the World node plays the role of connect node, and the Menu node acts as "emit signal", but initially the Menu node does not exist, then Godot will give an error that the Menu node does not exist so it cannot be connected. So is there any code that helps us to anchor the connect command to a node that doesn't exist yet? so that when it is initialized, then it is actually connected to the World node.Sorry I'm practicing coding. So everyone forgive me.

DaveTheCoder

So is there any code that helps us to anchor the connect command to a node that doesn't exist yet?

I'm fairly certain that's not possible. Why not use duane's suggestion to have the menu node make the connection?

duane

If you don't want to put the code in the menu node, then you could have the function that eventually creates the menu node also connect it.

fire7side

Can't you put a function in the menu script, like emit() instead of having it in the ready function?

Odin

Ok, since I've been implementing a Menu node containing Connect() before, because I wanted to ask if anyone knows a better way. ^{^So} in the end, there is no other way but that way. Thank you very much for everyone's help. I still have to do it the old way.