Operators overloading

[matovitch]

On Sunday, 19 May 2013 at 10:03:27 UTC, Timon Gehr wrote:
> 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;
>     }

Oh yes ! You are right...it takes a vertex in both cases. Thanks 
for losing your time with me. :-)