How Do I Handle Conflicts in Overloaded Method Signatures?

Question

Hi.

I have a feeling this question is a can of worms but I am going to ask anyway... :)

I have a method:

private MembershipUser GetUserFromReader(SqlDataReader reader)

And I want overload this method with a different return type:

private User GetUserFromReader(SqlDataReader reader)

But the compiler complains that the two methods have the same signature.

So, what is the best way to do this? I would prefer to not add an unnecessary parameter just to change the method signature.

I have played with the idea of doing something like:

private User GetUserFromReader(T reader)

But haven't really explored this in full yet. It seems like I'll need to make a bunch of changes with how I use my reader object.

Any ideas? What is the best practice when you have two overloaded methods of the same signature?

Thanks for helping out...

Answer 1

You can't change the return type on an overload. How is the compiler supposed to tell which one you want to use?

What you should do is return a common superclass of everything you might want to return, and then just return whatever is applicable.

Either that, or name the methods differently, since they clearly do different things.

Answer 2

Your only real options are:

1. Change the name of the function
2. Change the signature of the function

I hate to be trite, but there isn't a way around the restriction on differentiating methods solely by return type.

If one of the overloads is declared in a parent class then you can use the new keyword to "hide" the higher method from callers, but new (on a member declaration) is usually considered evil.

Answer 3

The simple answer is that, as far as C# is concerned, you can't. Overloading by return type is permitted (I think) by MSIL, but not by C#.

The only real choice (i.e, excluding adding a "dummy" parameter), is to call one method GetMembershipUserFromReader and the other GetUserFromReader

Answer 4

Why overload it? Why not just let the method say what it does, like so:

private MembershipUser GetMembershipUserFromReader(SqlDataReader reader)
private User GetUserFromReader(SqlDataReader reader)

Answer 5

If you really want to differentiate the return type, but use the same method signature, you could use generics:

private T GetUserFromReader<T>(SqlDataReader reader)

But it's much simpler to just rename the methods, as in Luhmann's answer.