Should this be a class member?

Question

A class implements a public function that calculates some value. During the calculation the function creates temp data that I also want to retrieve.

I could either add a class member that stores that data which I can get after the function has finished, or give the function another parameter so that the callee has to take care of it. So it's basically

class A {
    TempData member;
    ...
    public Output function(Input input) {
        // calculate return value and save temp data to member
    }
}

vs.

class B {
    ...
    public Output function(Input input, TempData fillme) {
        // calculate return value and save temp data to fillme
    }
}

My problem: both versions look wrong to me. The temp data doesn't really belong to class A and the function with the additional parameter in class B, I don't know...

Is there another solution? If not, which one of those two would you choose and why?

Answer 1

It sounds like you are struggling with a multi-output function problem. The best solution is to create a separate class that represents the return value of this function and holds your Output and TempData objects. Then you can cleanly return an instance of this class.