equivariant functions

[Christopher Wright]

Jason House wrote:
> Templates are non-virtual right now

That could be changed, but it would require a lot of bookkeeping in 
temporary files (and not object files). And it would interfere with 
precompiled libraries.

Once D gets decent runtime reflection, I'd like to get generics that 
would pretty much just hide a bunch of casts and reflection calls:

generic (T : class) void foo (T thing)
{
	int i = thing.someMethod();
	thing.otherMethod (10, true, new Object());
}

transforms to:
void foo (ClassInfo info, Object thing)
{
	int i = *cast(int*)info.getMethod ("someMethod").invoke!()(thing);
	info.getMethod ("otherMethod").invoke!(uint, bool, Object)(thing, 10, 
true, new Object());
}

But that's probably a bit much to ask.