Re: opDispatch(string name, E...) (E e) question.

[Simen Kjærås]

On Sun, 25 Mar 2012 22:45:57 +0200, bls <bizp...@orange.fr> wrote:
How do I "call" opDispatch(string name, E...)(E elements) ?
What I want to archive is to call f.i. fm.list with an arbitrary number  
of arguments without using

fm.list(1, "abc", 4L, 3.33);

Instead I would prefer
fm.list = (1, "abc", 4L, 3.33);

Is this somehow possible ?

No. However, this is:

fm.list = tuple( 1, "abc", 4L, 3.33 );

In that case, you probably want to use the overload
opDispatch(string name, E...)(Tuple!E elements)

and mark the other:
opDispatch(string name, E...)(E element) if ( !(E.length == 1 &&  
isTuple!(E[0])))

tuple, Tuple, and isTuple are found in std.typecons.


import std.variant;
import std.conv;
....
auto fm = FlexMap();

fm.ten = 10;
fm.ten = ["Ten", "Zehn", "Tein"];
fm.list = [20, 10, 2, 2, 44 ] ;
fm.list = "Hello opDispatch";

struct FlexMap
{
     Variant[] [string] map;

     Variant[] opDispatch(string name)()
     {
        return map[name];
     }
        
     Variant[] opDispatch(string name, E...)(E elements)
     {
        foreach(element; elements)
                        map[name] ~= to!Variant(element);
                return map[name];
     }
        
     Variant[] opDispatch(string name, T) (T t)
     {
        map[name] ~= to!Variant(t);
        return map[name];
     }          
}



Another question :
How do I bring in :

opDispatch(string name, T) (T[] t)

into FlexMap ?


It's possible to do with template constraints:

import std.traits : isArray;

void opDispatch(string name, T)(T t) if ( isArray!T )
{
    // Array specific.
}
void opDispatch(string name, T)(T t) if ( !isArray!T)
{
    // Single element.
}



One could also use static if:

Variant[] opDispatch(string name, T)(T t)
{
    static if ( is( T U : U[] ) )
    {
        map[name] ~= to!
    }
    else
    {
        // Whatever you want to do differently here.
    }
}