Question

Scenario:

class A { }

class B : A { }

class C<T> where T: A { }

Question

Why cant C<A> = C<B> when B is a subclass of A?
it throws the “cannot implicitly convert” error

Thanks

–UPDATE–
can i create an implicit method for that C<A> would recognize C<B>?

Answer 1

Use co-variant if you need to do this, and because co-variant just work only with interface and delegate, so define an interface with the magic word out instead of class:

interface IC<out T> where T : A
{
}

So, you can assign like you want:

class CA : IC<A>
{}

class CB : IC<B>
{ }

IC<A> x = new CA();
IC<B> y = new CB();

x = y;