Is this a good way to expose generic base class methods through an interface?
- by Nate Heinrich
I am trying to provide an interface to an abstract generic base class. I want to have a method exposed on the interface that consumes the generic type, but whose implementation is ultimately handled by the classes that inherit from my abstract generic base.
However I don't want the subclasses to have to downcast to work with the generic type (as they already know what the type should be).
Here is a simple version of the only way I can see to get it to work at the moment.
public interface IFoo
{
void Process(Bar_base bar);
}
public abstract class FooBase<T> : IFoo
where T : Bar_base
{
abstract void Process(T bar);
// Explicit IFoo Implementation
void IFoo.Process(Bar_base bar)
{
if (bar == null) throw new ArgumentNullException();
// Downcast here in base class (less for subclasses to worry about)
T downcasted_bar = bar as T;
if (downcasted_bar == null)
{
throw new InvalidOperationException(
string.Format("Expected type '{0}', not type '{1}'",
T.ToString(), bar.GetType().ToString());
}
//Process downcasted object.
Process(downcasted_bar);
}
}
Then subclasses of FooBase would look like this...
public class Foo_impl1 : FooBase<Bar_impl1>
{
void override Process(Bar_impl1 bar)
{
//No need to downcast here!
}
}
Obviously this won't provide me compile time Type Checking, but I think it will get the job done...
Questions:
1. Will this function as I think it will?
2. Is this the best way to do this?
3. What are the issues with doing it this way?
4. Can you suggest a different approach?
Thanks!
