Multiple types in one specialized D template

Question

Say I have to deal ushort and uint some way, but string differently. So guess I need one specialized template for string and other to both ushort and uint. Is it?

// for most
void func(T)(T var) { ... }

// for uint and ushort
void func(T: uint, ushort)(T var) { ... }

That is the idea, although the code can't compile. It's valid or very bad?

Answer 1

Try this:

void func(T)(T var) if ( is(T : uint) || is(T : ushort) )
{
   ...
}

void func(T : string)(T var)
{
   ...
}

You could also do it in one function:

void func(T)(T var)
{
    static if ( is(T : uint) || is(T : ushort) )
    {
        ...
    }
    else if ( is(T : string) )
    {
        ...
    }
    else
    {
        // handle anything else
    }
}

Answer 2

If you need only specific types, follow Peter's answer.
If you would like to cover all integral/numeric data and all string (including wstring and dstring) data types, then you could use helpers from std.traits module:

import std.traits;

void func(T)(T var)
{
    static if (isNumeric!T) { //  or isIntegral!T
        //...
    } else if (isSomeString!T) {
        //...
    }
    else {
        //...
    }
}

Answer 3

You are not precise understand his meaning mix multi template parameters should do like this void func(T...)(T args) { static if(T.length==2&&is(T[0]:int)&&is(T[1]:short)) { //do some thing func(int,short) }else static if(T.length==1&&is(isSomeString!T[0]) { }otherwise { static assert("unsupport function"); }

}