TSubclassOf upward cast

Development Programming & Scripting C++
1

I have two classes A and B, B is inherited from A:

UCLASS()
class A
{
…
}

UCLASS()
class B:A
{
…
}

now I’m having a function take a parameter of TSubclassOf<class A>
//declare of function
foo( TSubclassOf<class A> varClass )

However, I want to pass the parameter as TSubclassOf<class B>

//declare of varClass
UPROPERTY(…)
TSubclassOf<class B> varClass

//try to call foo by this variable
foo( varClass )

the compiler will send err:
error C2440: ‘initializing’ : cannot convert from ‘B*’ to ‘A*’

How should I avoid this? Since I found it really convenient of declaring varClass as TSubclassOf<> instead of UClass*.
I will prefer using TSubclassOf<> if I can solve this question.

2

Will this help at all?

3

No, what I’m trying to do is pass it as a parameter.
I don’t want to access any of its variable or function.

The best way I can thought is to modify the declaration of function, while keeping the variable type.

4

You can’t really cast TSubclassOf<> because it’s still pointer to UClass*, not YourClass*, and YourClass does not derive at any point from UClass.

5

It should work completely fine, since any TSubclassOf can be implicitly converted to UClass*. I just did a quick test and got no errors. In fact a quick look at the docs shows there is even a templated copy-constructor taking any TSubclassOf argument.

I’m guessing you just have a problem with your class declarations. Perhaps at the point you call the function one of the classes has only been forward declared or something?

6

yes, you are right!

Got no error at all if I include the header file.

Really appreciate your help.