Cast Object - get null

[Namespace]

On Thursday, 19 April 2012 at 15:48:29 UTC, Namespace wrote:
> It seems that i can't cast if i want a const Vector2D, neither 
> with castFromtObject nor with opCast. If i do it i get a very 
> long list of compile errors. It's no problem because i can deal 
> without cast to const but it would be usefull if you can show 
> me how i can use both, const and normal casts.

For example in this case

void foo(T)(const Vector2D!(T) vec) {
	bar(cast(Vector2s) vec);
}

void bar(const Vector2s vec) {

}

const Vector2f vf = Vector2f(23, 42);

Vector2s vs = Vector2s(vf);
Vector2s vs_ = cast(Vector2s) vf;

Vector2f vf_ = cast(Vector2f) vs;

Vector2s vs2 = Vector2s(23, 42);

if (vs2 == vf) {
	writeln("equal!");
}

foo(vf);
foo(vs);

i get this compiler errors:

cast.d(323): Error: template 
cast.Vector2D!(short).Vector2D.opCast matches more
than one template declaration, cast.d(285):opCast(U) if 
(is(Unqual!(U) == Vector
2D!(byte)) || is(Unqual!(U) == Vector2D!(ubyte)) || is(Unqual!(U) 
== Vector2D!(s
hort)) || is(Unqual!(U) == Vector2D!(ushort)) || is(Unqual!(U) == 
Vector2D!(int)
) || is(Unqual!(U) == Vector2D!(uint)) || is(Unqual!(U) == 
Vector2D!(long)) || i
s(Unqual!(U) == Vector2D!(ulong)) || is(Unqual!(U) == 
Vector2D!(float)) || is(Un
qual!(U) == Vector2D!(double)) || is(Unqual!(U) == 
Vector2D!(real))) and cast.d(
306):opCast(T) if 
(isImplicitlyConvertible!(typeof(this),const(T)))
cast.d(360): Error: template instance cast.foo!(short) error 
instantiating

I can avoid them if i change bar to

void foo(T)(const Vector2D!(T) vec) {
	static if (is(typeof(vec.x) == const float)) {
		bar(cast(Vector2s) vec);
	} else {
		bar(vec);
	}
}

Of course i must check for more then only "const float" but it is 
only a test case.
So it seems i have to change the cast operator. But i have no 
idea how.
I thougth that "inout" would help me, but i was wrong. So maybe 
you have some ideas?