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

[Chris Nicholson-Sauls]

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