Set iterators

[Allen Wirfs-Brock]

On Feb 14, 2012, at 3:45 AM, Andreas Rossberg wrote:

> On 14 February 2012 12:02, David Bruant <bruant.d at gmail.com> wrote:
>> Le 14/02/2012 11:23, Andreas Rossberg a écrit :
> 
>>> And I see potential reasons why order might differ for separate
>>> iterations over the same collection.
>> 
>> I'm interested in hearing more :-)
> 
> Dynamic changes of representation, for example. V8 does things like
> that all the time. And it currently goes to some length to make for-in
> deterministic.
> 

Good hash table designs typically rehash (reorganize) themselves when they reach a certain percentage of their total capacity or are experiencing too many hash collisions. One of the simplest  iteration strategies for a hash table is often physical placement order. Rehashing will typically change the physical placement of entries and hence that ordering.

Allen 

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