[Zope-dev] TreeVocabulary in zope.schema.vocabulary

[Marius Gedminas]

On Thu, Jan 26, 2012 at 04:02:54PM +0200, Jan-Carel Brand wrote:
> On Wed, 2012-01-25 at 18:56 +0100, Souheil CHELFOUH wrote:
> > A quick note :
> > 
> > This quite an advanced vocabulary, why not make another package with a
> > dependency on zope.schema ?
> > I don't quite see the point to have that in the "core".
> 
> Ok, Charlie also expressed his reservations. I'll put it in a different
> package then.
> 
> I'm not too sure what to name it though. For example, under what
> namespace? zope or z3c?

My gut feeling says "z3c".

OTOH I don't think a single class warrants a whole separate PyPI
package.  Especially if it's going to be used with z3c.form (hint, hint
;) or that collective.forgotthenamealready you mentioned upthread.

> I'm guessing zope.vocabulary, or rather zope.treevocabulary?

(Or z3c.treevocabulary)

But I'd rather see this in zope.schema.

Incidentally, since this would be a new feature, it would need a minor
version bump in setup.py (4.0.2dev -> 4.1dev).

> > Furthermore, for the dict class in use in the vocabulary, you could
> > add a "factory" class that can be overriden easily.
> > That would allow people with OrderDict capabilities to use them
> > without having to re-sort later on.
> 
> Could you please elaborate on what you mean?

I think he meant something like

    class TreeVocabulary(object):

        # you can subclass and use OrderedDictionary instead
        dict_factory = dict

This would mean that you can't subclass dict and would instead have to
delegate __getitem__, __iter__, __len__, keys, values, items and all the
rest by hand.

I'm actually feeling a bit guilty about raising this question.  As I
said, I don't have a use-case for ordered TreeVocabularies myself.  (Or
unordered ones either, for that matter ;)  The only reason for hashing
this out now is to avoid painful API changes if we ever decide that we
need those.  Feel free to cry YAGNI at any time.  It's already hard
enough to contribute to zope3-or-is-it-bluebream-or-is-it-ztk-aaaugh as
it is, without us adding extra barriers in place.

> If I create a factory class to create TreeVocabulary instances, how will
> overriding that factory (without creating a separate
> SortableTreeVocabulary) allow people to use OrderedDict?
> 
> Incidentally, I came upon this: http://pypi.python.org/pypi/ordereddict
> which provides the OrderedDict to Python 2.4 to 2.7

Oh, neat.  I've used http://pypi.python.org/pypi/odict in the past, but
it doesn't have the blessing of stdlib'ness.

> I think it might make sense to just subclass OrderedDict and implement
> an ordered tree from the start.

> > By the way, good work on that, it's something that is often needed in
> > advanced forms. I'll make sure to try it.
> > Thank you for the effort.
> 
> Thanks! Much appreciated.

Thanks!

Marius Gedminas
-- 
http://pov.lt/ -- Zope 3/BlueBream consulting and development
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