UFUNCTION optional parameters?

Development Programming & Scripting
1

Hi guys,

I am writing a class, and I would like to use some UFUNCTIONs in it, which will have default argument values (so that you may or may not specify them, while calling functions from Blueprints). How do I do that? So far, I did not find a single line in engine code or in docs, that explain this optional parameter specifier.

I have tried these versions:

UFUNCTION(BlueprintCallable, Category = Mechanics)
void forceInitItem(uint16 itemLvl = 1);

this throws compilation error from UBT: “C++ Default parameter not parsed: itemLvl "1"”

FUNCTION(BlueprintCallable, Category = Mechanics)
void forceInitItem(optional uint16 itemLvl = 1);

This simply gives error like “unrecognized keyword “optional””

So, what’s the right way?

2

Change uint16 to int32. For some reason not all parameter types seem to like taking default values. int32 will at least give you the same range of positive values.

1 Like
3

Whoa this is a cryptic piece of information :slight_smile:
Thanks man, that works now.

1 Like
4

To be more specific, not all native types have blueprint equivalents. The BP type ‘Integer’ is int32. The error isn’t ‘uint16 can’t have a default value’ but that you are trying to provide a type to blueprint that it can’t understand. If you removed the ‘BlueprintCallable’ part of the function you’d find the error to be resolved as well.

1 Like