Cast Object - get null

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Too early happy, now it seems opEquals wouldn't be called...
I tried this again:

U opCast(U)() const if (is(Unqual!U == Vector2D!byte) ||
		is(Unqual!U == Vector2D!ubyte) ||
		is(Unqual!U == Vector2D!short) ||
		is(Unqual!U == Vector2D!ushort) ||
		is(Unqual!U == Vector2D!int) ||
		is(Unqual!U == Vector2D!uint) ||
		is(Unqual!U == Vector2D!long) ||
		is(Unqual!U == Vector2D!ulong) ||
		is(Unqual!U == Vector2D!float) ||
		is(Unqual!U == Vector2D!double) ||
		is(Unqual!U == Vector2D!real))
	{
		return U(this.x, this.y);
	}

And normal casts works perfectly but what should i do if i get 
Object like in opEquals?
I think you want me to say what I understand now slowly: it does 
not work with Object. Isn't it?
It's a very unhappy solution to call

if (vs == Vector2s(vf)) as simply if (vs == vf)

If there any other solutions or any ideas to fix my solution in 
my previous post?