Question

I have inherited some code that uses the ref keyword extensively and unnecessarily. The original developer apparently feared objects would be cloned like primitive types if ref was not used, and did not bother to research the issue before writing 50k+ lines of code.

This, combined with other bad coding practices, has created some situations that are absurdly dangerous on the surface. For example:

---

Customer person = NextInLine(); 
//person is Alice
person.DataBackend.ChangeAddress(ref person, newAddress);
//person could now be Bob, Eve, or null

Could you imagine walking into a store to change your address, and walking out as an entirely different person?

---

Scary, but in practice the use of ref in this application seems harmlessly superfluous. I am having trouble justifying the extensive amount of time it would take to clean it up. To help sell the idea, I pose the following question:

How else can unnecessary use of ref be destructive?

I am especially concerned with maintenance. Plausible answers with examples are preferred.

You are also welcome to argue clean-up is not necessary.

Answer 1

I would say the biggest danger is if the parameter were set to null inside the function for some reason:

public void MakeNull(ref Customer person)
{
    // random code
    person = null;
    return;
}

Now, you’re not just a different person, you’ve been erased from existence altogether!

As long as whoever is developing this application understands that:

By default, object references are passed by value.

and:

With the ref keyword, object references are passed by reference.

If the code works as expected now and your developers understand the difference, it’s probably not worth the effort it’s going to take remove them all.