How use "toHash" without cast

[Namespace]

That is my Code:

[code]
class Vector2D(T) {
private:
	static Vector2D!(T) CastFromObject(Object o) {
		import std.typetuple;

		foreach (Type; TypeTuple!(byte, ubyte, short, ushort, int, 
uint, long, ulong, float, double, real)) {
			if (auto vec = cast(Vector2D!(Type)) o) {
				return cast(Vector2D!(T)) vec;
			}
		}

		return null;
	}
	
public:
	T x;
	T y;
	
	this(T x, T y) {
		this.x = x;
		this.y = y;
	}
	
	static Vector2D!(T) opCall(T x, T y) {
		return new Vector2D!(T)(x, y);
	}
	
	float Summe() const pure nothrow {
		return this.x + this.y;
	}
	
	override bool opEquals(Object o) const {
		if (o is null) {
			debug {
				writeln("Object is null ;)");
			}

			return false;
		}

		const Vector2D!(T) vec = CastFromObject(o);

		if (vec is this) {
			return true;
		}

		return (vec.x == this.x) && (vec.y == this.y);
	}
	
	override hash_t toHash() const pure nothrow {
		return this.x + this.y;
	}
	
	override int opCmp(Object o) const {
		if (o is null) {
			return -1;
		}

		const Vector2D vec = CastFromObject(o);

		if (vec is this) {
			return 0;
		}

		if (this.Summe() > vec.Summe()) {
			return 1;
		}

		if (this.Summe() < vec.Summe()) {
			return -1;
		}

		return 0;
	}
	
	override string toString() const {
		return "Vector2D!(" ~ T.stringof ~ ")(" ~ to!(string)(this.x) ~ 
", " ~ to!(string)(this.y) ~ ")";
	}
}

[/code]

I have dmd 2.059 and with my current version of toHash i get the 
compiler errors, that he cannot implicit convert from float, 
real, double, long and so on to uint.
I cannot solve the problem with a simple cast or to!uint because 
then he said that casts form float to uint are not allowed or 
that to! isn't trusted and nothrow. I hate such annoying errors...