Re: Comparing DS_HASH_TABLE objects

On Wed, Jun 3, 2009 at 6:36 PM, Helmut Brandl <[email protected]> wrote:
> In my opinion the notion of equality in Eiffel is not very consistent.

I would say it is consistent, but definitely not trivial. :-) The
general notion of equality is certainly not trivial!

> So regardless whether an entity is reference or expanded, feature calls
> are done in the same manner. If it comes to equality testing, we have to
> use different operators to test for equality (surely you can write 200 ~
> 200 instead of 200 = 200, but it reads ugly).

I agree. Maybe "==". would look nicer.

> The we have the difference between deep equality and normal equality. In
> generic classes like hash tables or even simple arrays it is difficult
> to take all the differences into account.

Yes. I agree.

> So for me, the problem is not in Eric's implementation of the hash
> tables, the problem is in the concept of equality in Eiffel.

No. I just want to be clear that my postings are in no way a criticism
of DS_HASH_TABLE. I just wanted to understand and discuss the
rationale and possible approaches to doing equality tests of hash
tables. I think Eric's approach with moving the equality testers for
keys and items "outside" of the hash table is good.

/Paul

-- 
Paul Cohen
www.seibostudios.se
mobile: +46 730 787 035
e-mail: paul.cohen-qf2BM/[email protected]


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