[Zope-dev] difference between OOSet and OOTreeSet?

[Gary Poster]

On Mar 2, 2007, at 2:42 AM, Chris Withers wrote:

> Gary Poster wrote:
>>> Okay, so I want a persistent, ordered sequence which is quick to  
>>> find items in and which doesn't re-store the whole sequence when  
>>> an item is inserted or removed.
>>>
>>> What should I be using?
>> Ordered, as in sorted?  Or ordered, as in user-determined order?
>
> Ordered as in sorted, thankfully :-)

:-)

>> If sorted, use BTreeSet (or the keys of a BTree).
>
> As in OOTreeSet, right?

Yes.

>> Even though my assertion is right semantically for "Set", this is  
>> a BTreeSet, and I don't see this behavior changing ever.
>
> *phew*
>
>>  No, it isn't a sequence, so `reversed` won't work, but `list`  
>> will always give you the same order.
>
> Well, you can iterate over it...
>
> Am I right in thinking I can get the reversed semantics I want by  
> negating the numeric part of insert?
>
> s = OOTreeSet()
> s.insert(-myvalue)
> s.insert(-someothervalue)
>
> ...I just have to remember to re-negate them when I get 'em out?

Yeah, that would work.

>> "Set" does not match the  "doesn't re-store the whole sequence  
>> when an item is inserted or removed" requirement.
>
> But OOTreeSet does, right?

Yes.

>> In both cases, IMO you'll want your data to be of homogenous types.
>
> Yep, DateTimes all the way, or if you can't negate them,  
> DateTime.timeTime's

Cool.  I doubt you can negate the old Zope DateTimes, but who knows  
what tricks that class has up its sleeve.  ;-)

Gary