Hi, On Thu, Mar 12, 2015 at 9:44 PM, Sergiu Dumitriu <[email protected]> wrote:
> On 03/12/2015 07:24 AM, Eduard Moraru wrote: > > Hi, > > > > On Thu, Mar 12, 2015 at 12:03 PM, [email protected] <[email protected] > > > > wrote: > > > >> Hi Edy, > >> > >> On 12 Mar 2015 at 10:49:29, Eduard Moraru ([email protected](mailto: > >> [email protected])) wrote: > >> > >>> Hi, > >>> > >>> As it's documentation [1] mentions, the usage of the @Priority > annotation > >>> should be defined by the classes it is used on: > >>> > >>> "The effect of using the Priority annotation in any particular instance > >> is > >>> defined by other specifications that define the use of a specific > class. > >>> For example, the Interceptors specification defines the use of > priorities > >>> on interceptors to control the order in which interceptors are called." > >>> > >>> Therefore, I suggest we use the @Priority annotation on components that > >>> need it and that like to specify the order in which they are *used* > (i.e. > >>> perform their main task). > >> > >> so what you’re suggesting is that: > >> > >> @Component > >> @Name(“content”) > >> @Priority(1000) > >> public class ContentMacro implement Macro > >> > >> has a different meaning than: > >> > >> @Component > >> @Named(“XWiki.WatchListJobClass") > >> @Priority(1000) > >> public class WatchListJobClassDocumentInitializer ... > >> > >> because one if a Macro and the other one is a Document Initializer > >> > >> right? > >> > > > > ...and because they clearly express it, in their documentations, that > they > > accept some annotations and they define how those annotations will be > > interpreted. Basically, the purpose of the javax.annotations package. > > > > > >> (BTW note that this wouldn’t work if in the future we start supporting > >> several roles per component impl.) > >> > >> So it means that people reading the code need to understand that even > >> though it’s the same annotation, it’ll have a different meaning. > >> > >> Compare this to: > >> > >> @Component > >> @Name(“content”) > >> @MacroPriority(1000) > >> > > > > I don`t find this better since it does not tell me what the macro does > with > > that priority. @MacroExcutionPriority would have been clear, if that is > > what we pursue. > > > > public class ContentMacro implement Macro > >> > >> and > >> > >> @Component > >> @Named(“XWiki.WatchListJobClass") > >> @DocumentInitializerPriority(1000) > >> public class WatchListJobClassDocumentInitializer ... > >> > >> IMO the second one is more clear in its intent. WDYT? > >> > > > > Honestly, I am not a big fan of annotations, specially in Java, and I try > > to keep them to a minimal as much as possible. It feels like a shortcut > > that leads to a dead end. They are not code, but configuration and, as > > such, modifying configuration should not require recompiling the code. > > > > Back to our particular discussion, AFAIK, we are not doing multiple roles > > per implementation. That, indeed, would probably not work with the javax > > Priority annotation due to lack of specificity. > > > > I do see the advantages of typed annotations, but also the need to be > aware > > of more and more annotations, as they come, when our usecase is pretty > > simple and would be well satisfied by the javax Priority one. That is the > > main reason why I looked for a more generic solution instead of just > making > > a new annotation for the document initializer use case. I find it > uselessly > > polluting. > > > > I`d love to hear more opinions on this :) > > For your love, here's another opinion. > Always appreciated :) > > 1. I spent a while looking for javax.annotations.Priority, since I > didn't see it at > > http://docs.oracle.com/javase/7/docs/api/javax/annotation/package-summary.html > ... Turns out it's a JEE class that's not in JSE. AFAIK, we're not > really using JEE yet, just JSE with a few JEE modules. Am I wrong? If > not, do we want to require JEE from now on, or is that annotation > available in a Maven Central library that doesn't bring in the whole JEE? > Just an individual library: http://mvnrepository.com/artifact/javax.annotation/javax.annotation-api/1.2 > > 2. I agree with you that this is configuration, not code, thus changing > it shouldn't require recompiling code. I'm -0.5 for the original > proposal because of this. > > 3. I'd like to resurect http://markmail.org/thread/mrbmbn45cltfvh57 and > enhance/build on top of it. Since we're already using an external file > for listing components, and since we already have a kind of priority in > that file, why not use that file to also give components priorities. If > someone wants to change the priority of a component, all that's required > is to add a new file in WEB-INF/classes with the new priority of the > component. > Re 2) and 3): I also thought about externalizing all of this into a file, but I do not think this is the right situation where this applies. For instance, in JPA annotations, I would agree: That stuff belongs in a configuration file, not in class annotations. However, for components, it's not really something you get to configure that often. Also, if for JPA you had control over the DB to change things so a config file would be handy to just fix the config without a recompile, for components everything is related to code. If you want to change something, i.e. a priority, you do it because you changed some code that needs this config modification, so these annotations are tightly related to the code (i.e. you have to build something anyway) and I see no advantage in externalizing them in a config file. I am not completely against annotations, just against abusing them. 2) seems to suggest that you would like us to remove them (all component annotations, since you revived the discussion on 3) altogether. Re 3), AFAIR (did not re-read it now, just scanned it quickly), I believe that file only makes sense for the component manager and component related priorities like default implementation priority, execution priority and dispose priority. Anything else that is related to how a specific component is used by another specific component (i.e. not the component manager itself; e.g. How the macro manager is running macros or how the transformation manager is running transformations or whatnot), IMO, does not belong in that file. Thanks, Eduard > Before we discuss a syntax, anybody wants to veto this? > > > Thanks, > > Eduard > > > >> > >>> Priorities on other behaviors that are added to a component (for > example > >>> through interfaces like Initializable or Disposable, interfaces which > are > >>> not components themselves) should provide their own specialized > >>> (behavior-driven) priority annotations (e.g. @DisposePriority, > >>> @InitializationPriority, etc.). > >>> > >>> Note: If we want to explore the possibility of using our own generic > >>> Priority annotation, we need to consider the fact that multiple > >> annotations > >>> on the same java class is only supported [1] starting with java 1.8. > >> Until > >>> then, the commonly used workaround [3] seems cumbersome to use. > >> > >> Yep, I’d really not like to use a generic annotation with the namespace > >> being specified. I much much prefer typed annotations. > >> > >> Thanks > >> -Vincent > >> > >>> Thanks, > >>> Eduard > >>> > >>> ---------- > >>> [1] http://docs.oracle.com/javaee/7/api/javax/annotation/Priority.html > >>> [2] http://bugs.java.com/bugdatabase/view_bug.do?bug_id=7151010 > >>> [3] > >>> > >> > http://stackoverflow.com/questions/1554112/multiple-annotations-of-the-same-type-on-one-element > >>> > >>> On Thu, Mar 12, 2015 at 10:41 AM, [email protected] > >>> wrote: > >>> > >>>> Hi devs, > >>>> > >>>> As part of http://jira.xwiki.org/browse/XWIKI-11905, Edy has started > >>>> using the Java @Priority annotation. > >>>> > >>>> This seems very good and I personally didn’t know about this > annotation > >>>> before (maybe it’s been introduced not that long ago?). So for me it > >> raises > >>>> the question of: do we want to use this annotation more and how does > it > >>>> compare with what we’ve done so far. > >>>> > >>>> I can think of a few places that could have used it: > >>>> > >>>> * Macros.get/setPriority(). It should be possible to add support for > >>>> @Priority and modify MacroTransformation to use that annotation. > >>>> * Transformations. We have a jira issue opened for adding support for > >>>> Priority in Transformation’s executions (in TransformationManager). > >>>> * @DisposePriority (used by ECM). > >>>> * TranslationBundle.get/setPriority() > >>>> * … and probably some other places… > >>>> > >>>> However, I think there’s a namespacing problem. For example imagine > >> that > >>>> we code a Macro and set @Priority on that Macro component. The ECM > >> could > >>>> interpret it as a dispose priority while the MacroTransformation could > >>>> interpret it as an execution priority… > >>>> > >>>> Globally I think that use an annotation for expressing priority is > >> great > >>>> and much better than what we’ve done in the past with > get/setPriority() > >>>> methods. It’s better because priority is not a business concept and > >> we’re > >>>> polluting the business interface with it. > >>>> > >>>> Now, in order to fix the namespacing issue, I think that the best > >> solution > >>>> is that each module requiring some priority should introduce its own > >>>> annotation and should NOT depend on the @Priority one from the JDK > >> (i.e. we > >>>> ban the usage of it). > >>>> > >>>> WDYT? > >>>> > >>>> Thanks > >>>> -Vincent > >>>> > >>>> > >>>> W > > -- > Sergiu Dumitriu > http://purl.org/net/sergiu > _______________________________________________ > devs mailing list > [email protected] > http://lists.xwiki.org/mailman/listinfo/devs > _______________________________________________ devs mailing list [email protected] http://lists.xwiki.org/mailman/listinfo/devs
