Re: Operators overloading

[Timon Gehr]

On 05/19/2013 09:32 AM, matovitch wrote:
Okay, putting the if inside is quite easy :

It is not a valid transformation. This removes the condition from the 
signature.

     const Vertex opBinary(string op)(const ref Vertex vertex)
     {
         static /*[...]*/ if (op == "+" || op == "-")
         {
             Vertex result = *this;
             mixin("result" ~ op ~ "= vertex;");
             return result;
         }
     }

But...I'd like to define cross product :

     const T opBinary(string op)(const ref Vertex vertex)
     {
         static if (op == "*")
         {
             T result = 0;
             foreach(i; 0..vertex_size)
                 result += coordinate[i] * vertex.coordinate[i];
             return result;
         }
     }

The compiler is not so great here and doesn't distinguish the two
opBinary by their signatures. Why ?

Because the two signatures are identical.

const T opBinary(string op)(const ref Vertex vertex);

Do this:

    const Vertex opBinary(string op)(const ref Vertex vertex)
    if (op == "+" || op == "-"){
        Vertex result = *this;
        mixin("result" ~ op ~ "= vertex;");
        return result;
    }

    const T opBinary(string op)(const ref Vertex vertex)
    if (op == "*"){
        T result = 0;
        foreach(i; 0..vertex_size)
            result += coordinate[i] * vertex.coordinate[i];
        return result;
    }