associative arrays: iteration is finally here

[Andrei Alexandrescu]

Pelle Månsson wrote:
> Andrei Alexandrescu wrote:
>> Walter has magically converted his work on T[new] into work on making 
>> associative arrays true templates defined in druntime and not 
>> considered very special by the compiler.
>>
>> This is very exciting because it opens up or simplifies a number of 
>> possibilities. One is that of implementing true iteration. I actually 
>> managed to implement last night something that allows you to do:
>>
>> int[int] aa = [ 1:1 ];
>> auto iter = aa.each;
>> writeln(iter.front.key);
>> writeln(iter.front.value);
>>
>> Two other iterations are possible: by key and by value (in those cases 
>> iter.front just returns a key or a value).
>>
>> One question is, what names should these bear? I am thinking of makign 
>> opSlice() a universal method of getting the "all" iterator, a default 
>> that every container must implement.
>>
>> For AAs, there would be a "iterate keys" and "iterate values" 
>> properties or functions. How should they be called?
>>
>>
>> Thanks,
>>
>> Andrei
> aa.each, aa.keys and aa.values seem good names?

The latter two would break existing definitions of keys and values.

> Also, foreach with a single variable should default to keys, in my opinion.

That is debatable as it would make the same code do different things for 
e.g. vectors and sparse vectors.


Andrei