Question

I recently ran into a problem where it seems I need a ‘static abstract’ method. I know why it is impossible, but how can I work around this limitation?

For example I have an abstract class which has a description string. Since this string is common for all instances, it is marked as static, but I want to require that all classes derived from this class provide their own Description property so I marked it as abstract:

abstract class AbstractBase
{
    ...
    public static abstract string Description{get;}
    ...
}

It won’t compile of course. I thought of using interfaces but interfaces may not contain static method signatures.

Should I make it simply non-static, and always get an instance to get that class specific information?

Any ideas?

Answer 1

Combining static and abstract is somewhat meaningless, yes. The idea behind static is one need not present an instance of the class in order to use the member in question; however with abstract, one expects an instance to be of a derived class that provides a concrete implementation.

I can see why you’d want this sort of combination, but the fact is the only effect would be to deny the implementation use of ‘this’ or any non-static members. That is, the parent class would dictate a restriction in the implementation of the derived class, even though there’s no underlying difference between calling an abstract or ‘static abstract’ member (as both would need a concrete instance to figure out what implementation to use)