Revamping associative arrays

[BCS]

Hello Moritz,

> On Sat, 17 Oct 2009 18:58:08 +0000, BCS wrote:
> 
>> Hello Chris Nicholson-Sauls,
>> 
>>> Idea: the .keys and .values properties, rather than creating arrays,
>>> could create iterable ranges with the smallest possible footprint,
>>> internally walking the tree structure.
>>> 
>> what will this do?
>> 
>> foreach(key; aa.keys)
>> if(Test(key))
>> aa.remove(key);
>
> It's undefined behavior.
> You shouldn't try to mutate the aa while iterating.
> I hope that will be fixed.
> It took me some time to find this out.

That's the reason for the above idiom. Under the current spec, the above 
is totally valid and, as far as I know, the only valid way to remove all 
elements fitting some test with only a single pass.

Whatever is chosen, the above code had better work or at a minimum, requiter 
nothing more than the addition of a .dup

OTOH building .keys must do a pass of it's own so all that's gained is sugar. 
But still, switching to a .keys that gets invalidated on updating the AA 
will break existing code so making the fix simple should be kept in mind.