[Zope-dev] Re: Zope 2.7: OrderSupport for ObjectManager

[Yuppie]

Hi Chris!


Thanks for your feedback.

Chris McDonough wrote:
> I'm a bit uncomfortable with the sort-by-subobject-attribute code in
> orderObjects (the code that is called when sort order is not
> "position").
> 
> I'm wondering if a generic "IndexedFolder" implementation might be
> better for this behavior, where the user may define one or more indexes
> on the container itself.  The indexes could named after attributes of
> subobjects.  The indexes and a sort function for each index would be
> maintained on the container, and the API methods objectValues,
> objectIds, etc.would consult the indexes to return objects in sorted
> order dynamically (as opposed to just returning the presorted list of
> _objects, which needs to be manipulated statically after each
> insertion).

Well, you could use 'orderObjects' for that use case if you write some 
code that does the necessary manipulation after each insertion. But we 
included it for another use case:

Sometimes people want to maintain a user-specific order, but want to 
start from a sorted order. E.g. if most sub-objects should be ordered by 
'title', but some special sub-objects should be at top of the container.


I like your ideas of "IndexedFolder". And there are the two methods 
'getDefaultSorting' and 'setDefaultSorting' in OrderSupport that do 
something similar in a very basic way.

> This might be an argument to ditch the dynamic sorting feature until we
> better understand the use cases.  That said, the feature isn't exposed
> in the mgmt interface, so it might be ok.  But if people come to rely on
> it, it will be difficult to remove (and will never ever go away).

AFAICS, 'orderObjects' would still be useful for the use case described 
above. 'getDefaultSorting' and 'setDefaultSorting' provide a small 
subset of the API you propose and should play well with any "IndexedFolder".


Cheers,

Yuppie