Programming to Interfaces simplification

[Frustrated]

http://dpaste.dzfl.pl/c25655e2dfe9

The code above simplifies using interfaces as the programming
object. It allows one to program the derived classes as if they
were not part of an abstraction by mapping the abstracted virtual
methods to concrete methods.

e.g.,

class WindowsGui : iGui
{
	WindowsButton _button;
	@property WindowsButton button(WindowsButton b) { return
(_button = b); }
	
	mixin(Fixup!(WindowsGui, iButton, WindowsButton));
}

instead of

class WindowsGui : iGui
{
	WindowsButton _button;
          @property iButton button(iButton b)
          {
              assert(cast(WindowsButton)b !is null, `Invalid object
type dependency mismatch! Type: `~b.classinfo.name~` Type
Expected: WindowsButton`);
              auto bb = cast(WindowsButton)b;
              // do work with bb.
          }
}

(note the check and the cast are required for all usages of
iButton if one wants to treat it as a WindowsButton. By using the
mix, no checks and no casts are required. Much cleaner looking
and less verbose code results, which is the whole point.)

One problem with the template is that b.classinfo.name returns
the interface instead of the actual class.

In the example on dpaste, b.classinfo.name returns iButton, the
base interface of LinuxButton. I want to display the actual class
name that causes the problem(LinuxButton trying to be used where
a WindowsButton goes).

Obviously the Fixup template is not robust nor optimized for all
cases but should handle most.