What is the difference between a generic method limited by inheritance and a base class parameter?

Question

Suppose I have the following code:

public class BaseClass { }
public class DerivedClass : BaseClass { }

public void GenericMethod<T>(T input) where T : BaseClass
{
 //code
}

public void NormalMethod(BaseClass input)
{
 //code
}

My question is what is the difference between the two methods? Is there any advantages or disadvantages to either method, and why?

Answer 1

What is the difference between the two methods?

Basically none.

Is there any advantages or disadvantages to either method?

At best there is a slight (compile-time) performance improvement when you use the non-generic version, since that doesn't need a specific version of the method to be compiled. Otherwise, there is nothing significant I can think of.

What could be a use case for using generics here:

• When you would return T ;
• When T needs to derive from a class and an interface;
• If your class uses a type argument, you could follow that over specifying the required type again.

Answer 2

It makes little sense to use generics in the code you show.

On the other hand, if you were to return T as opposed to BaseClass from that method, the caller can access T -specific members instead of only members declared on BaseClass (unless they cast the return value).