18 Mar
2008
18 Mar
'08
1:23 p.m.
ok I see
But do we agree that we shall have a class/mechanism deletion somewhere? (in
fact I agree with myself about that at least because I'm frustrated not to
be able to delete the classes I don't need anymore :))
I'm not sure about something: did you intend to give to the concept of
"class" about the same "generic" extend as the concept of
"class" in any OO
language? Is a class a kind of descriptor of entities with their own
properties and relations to other entities? or is a class only a convenience
for gathering properties and creating objects with these properties?
If XWiki classes are real classes (I think they are) then it would be nice
to push the concepts as far as possible... Moreover, with XE (that I don't
have installed yet), it would be nice to be able to manage classes directly
and to have refactoring features :)...
Pascal
On Tue, Mar 18, 2008 at 12:52 PM, Ludovic Dubost <ludovic(a)xwiki.org> wrote:
Yes but we need tons of warning in case properties are deleted.
If class are deleted this is even more problematic as this can make a
lot of deletion.
For versioning, what we do is we store in the XML of each object the
definition of the class at the time the object was saved. This means we
can build the class as it was before we actually load the object.
Now I'm pretty sure we don't really make use of that.
Ludovic
Pascal Voitot wrote:
with
That's what I think...
In a ideal world, removing a class or a property should imply removing
associated instances naturally...
Another idea...One question: are classes and properties versioned as
documents? I mean, if you modify a class, is it possible to keep the
previous version and keep existing objects as instantiations of the
older version and then new objects will be instantiations of the newer
version of the class? We could also propose an object to be
translated into the newer version with some risks.
In this case, it could be simple to modify or remove properties of a
class even if it would bring some complexity also...
Then the last problem would be class deletion which would be more
violent and would need some strong warnings because objects would be
deleted definitely... in this case, a kind of temporary bin could be
interesting...
Pascal
On Tue, Mar 18, 2008 at 10:56 AM, Sergiu Dumitriu <sergiu(a)xwiki.com
<mailto:sergiu@xwiki.com>> wrote:
Pascal Voitot wrote:
> This might seem stupid but what are the limitations in
class/object
deletion?
We don't know what to do with the data. Adding a property is simple,
existing objects will not have a property and it will be added
when the
object is saved. But when you delete a property, what do we do?
Leave it
there? Delete it from all the objects?
If we keep it there, it will be "shadowed", as the persistence layer
will not know that it exists. More, if we add back that property the same name and another type, we'll
have errors because we'll
have two
instances with the same identifier in two places (this is what
happened
when switching number types or the multiselect metaproperty of a
list
property).
If we remove it, then we'll completely remove a lot of data. And is
a
warning enough for that? Probably we need a
mass rollback utility
that
is able to revert bulk changes.
My take is that we should remove the data, but what do others think?
--
Sergiu Dumitriu
http://purl.org/net/sergiu/
_______________________________________________
devs mailing list
devs(a)xwiki.org <mailto:devs@xwiki.org>
http://lists.xwiki.org/mailman/listinfo/devs
------------------------------------------------------------------------
_______________________________________________
devs mailing list
devs(a)xwiki.org
http://lists.xwiki.org/mailman/listinfo/devs
--
Ludovic Dubost
Blog: http://blog.ludovic.org/
XWiki: http://www.xwiki.com
Skype: ldubost GTalk: ldubost
_______________________________________________
devs mailing list
devs(a)xwiki.org
http://lists.xwiki.org/mailman/listinfo/devs