Question

Is it considered good practice or bad practice to write an interface that exists solely to concentrate other interfaces?

interface InterfaceA : InterfaceB, InterfaceC {
}

In doing this, a concrete implementation only needs to implement InterfaceA, which seems like a good thing, but it doesn’t add any value by extending, which seems wasteful.

Answer 1

I think it depends on if it makes sense in your domain. If it does, I would do it, then your program more accurately models your domain.

In addition, of course, you can now write code which requires/uses objects implementing InterfaceA i.e. all methods of both the super-interfaces; that wouldn’t have been possible before.