On 06.03.2007, at 18:54, Christophe Combelles wrote:
Hi,
I'm playing again with the notion of categories of objects.
I have two main goals:
---------------------
1) I must let the user choose the category of an object added to
the zodb. For this, I must be able to retrieve the list of
categories and present them in a form field managed by a vocabulary
(or in a different manner).
2) I must have different behaviours for categorized objects:
objects of different categories would have different views,
different addMenuItems (if they are containers), etc.
the first requirement would tell me to define categories as
objects, while the second one would tell me to define them as
interfaces.
The possible solutions I see:
----------------------------
1) The simplest solution is to store the categories as text strings
into the annotations of the object. So categories actually are just
tags.
2) The second solution is to do the same, but replace text strings
with category objects, that implement ICategory. And categories can
be stored separately in a category container, or in a registered
utility that gives the list of available categories. This is a bit
better, but this way I don't know how to easily let my categorized
objects behave differently according to their categories.
3) The third solution is to define categories as interfaces
extending ICategory. I can retrieve the list of categories with
ICategory.dependents
But to present them in a form, I must have a pretty name for each
interface. Should I store them in a Tagged Value?
4) The fourth solution I see, is to define an interface type,
ICategoryType, extending IInterface just like IContentType. Then my
categories would be interfaces whose type is ICategoryType. But
with IContentType, is there a way to retrieve the list of all
available content types?
imho 4) is the best solution, just take a look at zope.app.content to
see how to get the vocabulary and the inspection implementation of
objects
you can then set the interface on objects by using
zope.interface.alsoProvides
regards, Bernd
Do you have some advice on the subject? Am I asking the wrong
questions? Is there an obvious solution I've not seen? Am I going
too far and should I rather keep it simple and stupid?
regards,
Christophe
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