Ludovic Dubost wrote: > > We have thought about the capability of having class heritage.. but it's > not so easy to implement.. > Want to work on it ?
Indeed, it is not so easy. Marta and I worked on it about a year ago, and we had a working prototype. But the changes were too big to commit all at once, so the code remained on a local computer while waiting for the new Data component for XWiki. > Ludovic > > Pascal Voitot wrote: >> 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 <[EMAIL PROTECTED] >> <mailto:[EMAIL PROTECTED]>> 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: >> > 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 >> <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> >> > <mailto:[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>>> 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 with >> > 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@xwiki.org http://lists.xwiki.org/mailman/listinfo/devs
