Re: [xwiki-devs] [Proposal] Define XClass property types using components

On Mon, Oct 22, 2012 at 11:33 AM, Marius Dumitru Florea &lt;mariusdumitru.florea(a)xwiki.com&gt; wrote: > On Mon, Oct 22, 2012 at 12:15 PM, Thomas Mortagne > &lt;thomas.mortagne(a)xwiki.com&gt; wrote: >> On Mon, Oct 22, 2012 at 10:36 AM, Marius Dumitru Florea >> &lt;mariusdumitru.florea(a)xwiki.com&gt; wrote: >>> Hi devs, >>> >>> Currently, the available XClass property types are hard-coded in >>> MetaClass [1]. So in order to add a new property type you need to >>> recompile the XWiki old core. I'd like to be able to create new >>> property types using components so I created this branch [2] that >>> includes the following important changes: >>> >>> (A) Use the value of the "classType" XML element from the XAR as a >>> property type hint >>> >>> If you look at the XML export of an XClass you'll see that each >>> property has a "classType" element whose content is the full name of >>> the Java class used to implement that property type: >>> >>> <classType>com.xpn.xwiki.objects.classes.DBTreeListClass</classType> >>> >>> I think this is bad because: >>> * it exposes an implementation detail >>> * you cannot change the property type implementation without breaking >>> backwards compatibility >>> >>> So I'm proposing to use the "classType" as a hint for the property >>> type. Well, technically it will be a hint, but semantically it will >>> specify the data type of the property value (e.g. String, Date, >>> Number). For backwards compatibility, the existing property types will >>> have hints that can be extracted from the value of the 'classType' >>> (i.e. the full Java class name): >>> >>> String hint = >>> StringUtils.removeEnd(StringUtils.substringAfterLast(classType, >>> "."), "Class"); >>> >>> So both: >>> >>> <classType>com.xpn.xwiki.objects.classes.DBTreeListClass</classType> >>> <classType>DBTreeList</classType> >>> >>> will point to the property type with hint "DBTreeList". Of course, >>> when exporting an XClass with the new version of the core you'll only >>> see the property type hint. >>> >>> The only issue with this approach is that XClasses exported with the >>> new version will not work on an older version but this is acceptable >>> IMO. >> I don't like breaking stuff too much especially when it's far from > To be clear. This is not backwards compatibility. Are you sure that a > XAR from 4.2 can be imported in XWiki 1.0 for instance? In other > words, whenever we extended the XAR/XML format did we take care to > keep the new XARs working on older versions of XWiki? If the answer is > yes then I agree with your suggestions below. But for me it's enough > to ensure that older XARs work with newer versions of XWiki, not the > other way around. I don't have any breaking change in mind except that obviously a 2.0 document is not going to be parsed properly with XWiki version that only knows 1.0. Anyway the point is not if it's going to fully work with XWiki 1.0. I don't see any reason to break anything here and it's not even like either of my suggestions was introducing any important complexity in your proposal.

> Thanks, > Marius > >> mandatory technically. We could either: >> * keep theses old classType and have cleaner ones for new types. It's >> not a big deal IMO, we are talking about oldcore API here and we will >> have to introduce a new component API for this anyway with the new >> model. >> * or simply introduce a new field in the class which would fallback on >> String hint = >> StringUtils.removeEnd(StringUtils.substringAfterLast(classType, >> "."), "Class"); when it's not defined >> >>> (B) Add a PropertyClassProvider [3] role to retrieve an instance of a >>> property class and to access its meta class >>> >>> Currently, in order to define a new property type you need to create >>> two Java classes: >>> * one extending PropertyMetaClass, to define the list of meta >>> properties of the new property type (e.g. displayType, dateFormat, >>> multiSelect, etc.) >>> * one extending ProperyClass, to define setters and getters for the >>> meta properties and maybe some custom display. This is the property >>> type itself. >>> >>> So I added a PropertyClassProvider role that has two methods: one to >>> get the meta class and one to get a new instance of the property type >>> (e.g. when adding a property to an XClass). As a quick implementation >>> I transformed all meta classes into implementations of this role. >>> Finally, I modified MetaClass to lookup property class providers >>> instead of hard-coding the property types. >>> >>> WDYT? >>> >>> Note that I've not added any CLIRR excludes and I tested my changes >>> with the default, unchanged, class editor and it works fine. >>> >>> Thanks, >>> Marius >>> >>> [1] >>> https://github.com/xwiki/xwiki-platform/blob/xwiki-platform-4.2/xwiki-platf… >>> [2] >>> https://github.com/xwiki/xwiki-platform/compare/feature-xclass-property-com… >>> [3] >>> https://github.com/xwiki/xwiki-platform/commit/fb9fcc7313ccb16f38c2d17dd7ed… >>> _______________________________________________ >>> devs mailing list >>> devs(a)xwiki.org >>> http://lists.xwiki.org/mailman/listinfo/devs >> >> >> -- >> Thomas Mortagne >> _______________________________________________ >> devs mailing list >> devs(a)xwiki.org >> http://lists.xwiki.org/mailman/listinfo/devs > _______________________________________________ > devs mailing list > devs(a)xwiki.org > http://lists.xwiki.org/mailman/listinfo/devs -- Thomas Mortagne _______________________________________________ devs mailing list devs(a)xwiki.org http://lists.xwiki.org/mailman/listinfo/devs