Php type hinting not getting along with interfaces and abstract classes?

Question

I think it\'ll be much easier to see the problem in a code example than writing the question in the first place. Here is my php code:

Answer 1

Here's an example that shows, why this is not allowed:

method($b);
}

This would be a valid code, but it would fail, if you pass a ConcreteClass to moo, because its method ConcreteClass::method does not allow BClass.

It is complicated, but it is easier to understand, if you see an example.