Use new keyword if hiding was intended

I have the following snippet of code that's generating the "Use new keyword if hiding was intended" warning in VS2008:

public double Foo(double param)
{
   return base.Foo(param);
}

The Foo() function in the base class is protected and I want to expose it to a unit test by putting it in wrapper class solely for the purpose of unit testing. I.e. the wrapper class will not be used for anything else. So one question I have is: is this accepted practice?

Back to the new warning. Why would I have to new the overriding function in this scenario?

c# inheritance warnings new-operator

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1 Answer

The key is that you're not overriding the method. You're hiding it. If you were overriding it, you'd need the override keyword (at which point, unless it's virtual, the compiler would complain because you can't override a non-virtual method).

You use the new keyword to tell both the compiler and anyone reading the code, "It's okay, I know this is only hiding the base method and not overriding it - that's what I meant to do."

Frankly I think it's rarely a good idea to hide methods - I'd use a different method name, like Craig suggested - but that's a different discussion.

answered 2009-01-16T16:38:59.173

Use new keyword if hiding was intended

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