Sorry, I just love templates, AAs and mixins :)

[Saaa]

Chris Nicholson-Sauls wrote:
> Saaa wrote:
>> Ary Borenszweig wrote:
>>> Saaa wrote:
>>>> public void addToAA(char[] var_name, KT, ET)(KT key, ET element)
>>>> {
>>>>   mixin(ET.stringof~`[]* elements = key in `~var_name~`;`);
>>>>   if( elements == null )
>>>>   {
>>>>     ET[] temp;
>>>>     temp.length = 1;
>>>>     temp[0] = element;
>>>>     mixin(var_name~`[key] = temp;`);
>>> Why `key`? Where's `key` defined?
>> Here: ...(KT key, ET element)
>>>>   }
>>>>   else
>>>>   {
>>>>     (*elements).length = (*elements).length + 1;
>>>>     (*elements)[(*elements).length-1] = element;
>>> I don't understand this. Key is not used.
>> That's because there is already a link to the key through elements.
>>
>>>>   }
>>>> }
>>> And how do you use it? I tried to but I failed.
>> You need a AA defined like this:
>> BaseType[][KeyType] AAname;
>>
>> addToAA!("AAname")(KeyType key, BaseType value);
>>
>>> Also passing a string as var_name is not nice. Isn't it better to write 
>>> something like:
>>>
>>> char[int] x;
>>> x.add(1, 'h');
>>>
>>> ?
>>
>> The string is the actual variable name so I think that way doesn't work, 
>> right?
>>
>> Check the new version(shorter)  in my other reply :D
>>
>>
>
> This worked just now with DMD 2.035:
>
> ////////////////////////////// BEGIN CODE
> module test1;
>
> import std .stdio ;
>
> public void add ( AAA : E[][K], K, E ) ( ref AAA aa, K key, E[] elem ... ) 
> {
>     if ( auto ptr = key in aa ) {
>         *ptr ~= elem;
>     }
>     else {
>         aa[ key ] = elem;
>     }
> }
>
> void main () {
>     int[][ char ] sandbox ;
>
>     sandbox.add( 'a', 1 );
>     sandbox.add( 'b', 1, 2 );
>     sandbox.add( 'c', 1 );
>     sandbox.add( 'a', 2, 3 );
>
>     foreach ( key, elems ; sandbox ) {
>         writeln(`    [`, key, `] `, elems);
>     }
> }
> ////////////////////////////// END CODE
>
> -- Chris Nicholson-Sauls

Thanks, that looks nice.
One small difference is that  main() now needs to have access to sandbox 
whereas using mixins you could keep sandbox private to add()'s location.