[Zope-dev] difference between OOSet and OOTreeSet?

[Chris Withers]

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?

> 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?

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

But OOTreeSet does, right?

> 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

cheers,

Chris

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