How do I make a function delegate parameter optional?

Development Pipeline & Plugins Editor Scripting
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1

Hello,

I have a function with a Delegate (by ref) (or Event reference) Parameter which connects to a ‘Bind Event to’ node, but if I leave this input node blank, it does not allow me to compile the code and produces an error saying that it needs to have some sort of input.

How can I make it, so that it allows me to leave it blank? Is there a way to check if the input contains anything?

2

Make the delegate a const reference in the function declaration and then use the UFUNCTION meta property AutoCreateRefTerm like so:

DECLARE_DYNAMIC_DELEGATE(FLoadingComplete);

UFUNCTION(BlueprintCallable, meta = (AutoCreateRefTerm = "OnComplete"))
void ShowLoadingScreen(const FLoadingComplete& OnComplete);
3

Thanks! But this is a Blueprint Scripting question. Is it possible to do that in blueprints?

4

I was not aware that it was even possible to use a delegate as a parameter using blueprints only. The only way I managed to do it was by collapsing a Bind Event to... node. This makes me think that it wasn’t really an intended feature.

The C++ code above will create a function that is usable in Blueprint, if that’s an option for you.

5

Ah alright, thanks for the help! :slight_smile:

6

Suppose that a member function beside a delegate has some more arguments which all have their default values, then compiler asks for default value of that delegate too, otherwise it wont compile. How to resolve that? Is there a way to give a delegate also a default function whose node would be created and lbound to main node, everytime the user create node of the main function in BP?