Can I use a primitive type for a UPROPERTY?

Development Programming & Scripting
1

You definitly can use primitive types. Are you decorating your class correctly with the UCLASS macro?

2

I would like to expose a C++ “bool” primitive data type to blueprints so that I can check/uncheck the value in the editor, and based on Epic’s documentation, it looks like I can use a primitive data type (bool, int32) as a UPROPERTY. When I try, however, I get compiler errors which vary depending on what primitive type I use. Given that the errors are not consistent, I’m either missing a step, or one cannot, in fact, use primitive types this way. Can anyone help?

3

Hi Dijon, you certainly can use primitive types as properties. Make sure if it’s editable that you also specify a category, like this

UPROPERTY(EditAnywhere, Category = MySettings)
bool MyBooleanValue;

Also make sure the property is either public or protected.

I hope this helps.

4

Hi Alderbit,

I tried it that way, and it fails with:
error C2659: ‘=’ : function as left operand

If I change bool to int32, then it fails with:
error C2661: ‘UIntProperty::UIntProperty’ : no overloaded function takes 3 arguments

I must be missing something important.

5

Do you have a #include “YourClassName.generated.h” at the top?

Have you tried a clean and build?

Can you post some code?

6

Hi Michael,

Yes, I used the editor to generate the class to allow it to create the necessary boilerplate code. The class compiles and builds without problem, but when I add UPROPERTY(), UPROPERTY(EditAnywhere, Category = MySettings), or UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = MySettings), for example, then the build fails with errors similar to those that I posted in my comment to Alderbit’s response. Any other ideas?

7

Yes, the generated file is present.
Yes, I tried clean and build (a very slooooow process), but no change.
On a whim, I decided to rename my variable from isSelected to bSelected and it compiled. I went back through ACharacter, AActor, APawn but only found in UObject the property IsSelected (note the initial capital ‘I’). Could this be the cause? I wasn’t aware that a similar property existed but, even then, C++ is case sensitive, is it not? While my code now builds, I would really like to know why it failed. Can you help?

8

Blueprints might not be case sensitive - so autogenerated methods clashed? That’s probably it as IsSelected() is a function - so the below messages about ‘function as left operand’ and your bool taking 3 arguments make sense.

9

Thank you VERY much for taking the time to help me sort this out.