@Named is the same as marking a component in Plexus and giving it a hint - and just as you can have components with explicit hints/names, you can also have components without an explicit name. If you don't choose an explicit name then it will use the fully-qualified class as the name.
As for having multiple implementations and how they are selected - as Hervé mentioned before, this is the stock behaviour that Maven was built on (the semantics originated in Plexus and have been carried over as the runtime has evolved) and it's this that allows plugins/extensions to adapt and extend Maven. On Thu, 7 Nov 2019 at 09:45, Tibor Digana <tibordig...@apache.org> wrote: > Question. > Why we used @Named? I was talking about it in before that the names must > not be the same but i do not understand why we use @Named since there is no > benefit from expression language in Maven where the name of bean is only > useful as a reference to the bean. > Additionally, two beans having @Named @Singleton implementing the same > interface is a strange combination. Even if somebody wants to inject the > interface it will be the same problem. And the same with names. > > On Thu, Nov 7, 2019 at 4:48 AM Stuart McCulloch <mccu...@gmail.com> wrote: > > > The index generator is very simple and just indexes named classes, which > > makes it very fast with negligible impact on the build. > > > > To spot this kind of ambiguity at generation time would require a deep > > analysis of the type hierarchy and caching of those hierarchies to check > > for overlaps. > > > > This would quickly become messy (especially for the case where we're > > indexing via an annotation processor) compared to checking at runtime. > > > > Also in some ways this is better handled by application ITs. The > container > > doesn't really have enough context to definitively say "this is wrong" > > because it could be that the developer intended to have multiple > > implementations and plans to have them all injected into a list. It could > > also be that two implementations happen to share the same superclass or > > interface which would make them ambiguous if someone asked for an > > implementation at that particular type level, but in reality they are > only > > ever injected as different sub-types where there is no ambiguity. > > > > Compare this to checking at the application level: when adding a > > replacement component you'd just need an IT confirming that new component > > is being used. Most of the time the replacement is there to fix a bug, so > > you'd expect regression tests to catch if it wasn't used. Other reasons > to > > rewrite or replace a component are performance related, in which case you > > might also expect a performance related IT to verify the new > implementation > > is having an effect. > > > > On Thu, 7 Nov 2019 at 03:08, Gabriel Belingueres <belingue...@gmail.com> > > wrote: > > > > > @Hervé: The patch worked fine. Thanks! > > > > > > @Stuart: In the light that the model interpolator was the only case > > found, > > > that is, both equally qualifying classes were located inside the same > > > javax.injected.Named file, I wonder if it would be easier to check for > > > ambiguities at generation time, in the sisu-maven-plugin (adding an > > > optional parameter to fail the build if this kind of case is found). > > WDYT? > > > > > > Regards, > > > Gabriel > > > > > > > > > El mié., 6 de nov. de 2019 a la(s) 13:39, Herve Boutemy ( > > > hbout...@apache.org) > > > escribió: > > > > > > > MNG-6799 issue created [1] > > > > proposed fix added to the reproducible branch [2] by simply removing > > the > > > > @Named annotation for the deprecated StringSearchModelInterpolator: > CI > > > > seems ok > > > > ok for merge? > > > > > > > > Regards, > > > > > > > > Hervé > > > > > > > > [1] https://issues.apache.org/jira/browse/MNG-6799 > > > > > > > > [2] > > > > > > > > > > https://github.com/apache/maven/commit/16961b32b7dccbc9447ed4e18b4e0949d5fe3b56 > > > > > > > > On 2019/11/03 21:27:21, Stuart McCulloch <mccu...@gmail.com> wrote: > > > > > I did a quick review of the various components in core > > > > > and StringVisitorModelInterpolator / StringSearchModelInterpolator > > > > appears > > > > > to be the only case where a role (ModelInterpolator) has two > > > non-default > > > > > implementations and another component only asks for the first > > > > > implementation. There are other roles which have multiple > > > > implementations, > > > > > but in those cases that's expected because each implementation has > a > > > > > specific name and handles a specific case (see the various > > > > ProfileActivator > > > > > implementations which are all then injected into a list in > > > > > DefaultProfileSelector.) > > > > > > > > > > It also appears that StringVisitorModelInterpolator was only added > > > > recently > > > > > - if it's meant to be a replacement of > StringSearchModelInterpolator > > > then > > > > > one option would be to simply remove StringSearchModelInterpolator. > > > > > Alternatively if StringSearchModelInterpolator is needed to be kept > > > > around > > > > > for compatibility reasons (such as someone directly extending it > > > outside > > > > of > > > > > Maven) then the Named annotation could be removed > > > > > from StringSearchModelInterpolator so it isn't automatically picked > > up. > > > > > > > > > > Wrt. extra checks, checking for multiple implementations in the > same > > > > > realm/classloader that haven't been given specific names is a > > > > possibility - > > > > > you can open feature requests at > > > > > https://bugs.eclipse.org/bugs/describecomponents.cgi?product=Sisu > > > > > > > > > > On Sun, 3 Nov 2019 at 19:05, Gabriel Belingueres < > > > belingue...@gmail.com> > > > > > wrote: > > > > > > > > > > > Hi Hervé: > > > > > > > > > > > > I was thinking in the lines of some checking at the maven core > > level > > > > only, > > > > > > enough to detect problems and ensure there are no regressions. > > > > > > > > > > > > At the plugin level, I guess the assurance that the right > component > > > is > > > > > > injected can be checked with an integration test. > > > > > > > > > > > > The way I realized the problem was that I was adding some logging > > > > traces > > > > > > into the StringVisitorModelInterpolator class but *nothing* > showed > > > > (even > > > > > > the build was successful and the interpolation indeed was > happening > > > > > > somewhere). Then added the same logging lines to > > > > > > StringSearchModelInterpolator, and the logging appeared in the > > build, > > > > which > > > > > > confirmed the issue. (I didn't test if there are any other > > component > > > > with > > > > > > the same problem.) > > > > > > > > > > > > El dom., 3 de nov. de 2019 a la(s) 06:27, Hervé BOUTEMY ( > > > > > > herve.bout...@free.fr) escribió: > > > > > > > > > > > > > nice idea, but overriding by adding a new implementation in > > > > classpath is > > > > > > > the > > > > > > > normal overriding way: not sure how "ambiguity checker" could > > make > > > a > > > > > > > difference > > > > > > > between such wanted override vs unwanted ambiguity > > > > > > > > > > > > > > BTW, how did you see that StringVisitorModelInterpolator was > not > > > > used but > > > > > > > StringSearchModelInterpolator instead, please? > > > > > > > > > > > > > > Regards, > > > > > > > > > > > > > > Hervé > > > > > > > > > > > > > > Le dimanche 3 novembre 2019, 05:30:50 CET Gabriel Belingueres a > > > > écrit : > > > > > > > > Thanks Stuart. > > > > > > > > > > > > > > > > The reproducibility PR you mention helps in having a > > > deterministic > > > > > > > ordering > > > > > > > > inside the Named components file to buld exactly the same > > > > executable, > > > > > > but > > > > > > > > it does not mean it is the right priority for component > > > injection. > > > > > > > > > > > > > > > > Do you know if it is possible to configure sisu to throw an > > > > exception > > > > > > if > > > > > > > > trying to inject an ambiguous component? Otherwise, I guess > we > > > must > > > > > > > > implement some sort of "ambiguity checker", either as an > > > > integration > > > > > > test > > > > > > > > (don't know if it is possible) or either built-it into maven > > > > > > executable. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > El sáb., 2 de nov. de 2019 a la(s) 20:54, Stuart McCulloch ( > > > > > > > > > > > > > > > > mccu...@gmail.com) escribió: > > > > > > > > > Yes, when there are multiple non-default implementations > with > > > the > > > > > > same > > > > > > > > > priority then it will pick the first in the list (where the > > > > "list" in > > > > > > > > > question is actually a combination of plugins + extensions > + > > > core > > > > > > > > > bindings for the given type) > > > > > > > > > > > > > > > > > > If a particular implementation should be treated as the > > default > > > > then > > > > > > it > > > > > > > > > should either start with "Default" or be annotated with > > > > > > > @Named("default") > > > > > > > > > - > > > > > > > > > the benefit of this approach is that it documents that this > > is > > > > the > > > > > > > default > > > > > > > > > implementation, to be favoured over the others. > Alternatively > > > if > > > > you > > > > > > > want > > > > > > > > > to have an ordering between implementations then you can > use > > > > > > @Priority > > > > > > > to > > > > > > > > > assign specific priorities and favour one over the other. > > > > > > > > > > > > > > > > > > If you don't mark an implementation as default and don't > > define > > > > any > > > > > > > > > priorities then the only current guarantees are that > > > > implementations > > > > > > in > > > > > > > > > plugins and extensions will be favoured over > implementations > > in > > > > core > > > > > > > (to > > > > > > > > > allow overriding). But there is an upcoming improvement to > > sort > > > > the > > > > > > > list > > > > > > > > > inside each module that would make this more deterministic > > from > > > > build > > > > > > > to > > > > > > > > > build, at least when ranking implementations inside a > > > particular > > > > > > > module: > > > > > > > > > https://github.com/eclipse/sisu.inject/pull/5 - with that > > > change > > > > > > then > > > > > > > > > you'll get an extra guarantee that inside a module it will > be > > > > ordered > > > > > > > by > > > > > > > > > package+name. > > > > > > > > > > > > > > > > > > PS. even with the old Plexus runtime annotations you could > be > > > at > > > > the > > > > > > > whim > > > > > > > > > of classpath ordering, similarly Plexus XML descriptors are > > > > > > influenced > > > > > > > by > > > > > > > > > classpath resource ordering - so ideally it's better to be > > > > explicit > > > > > > > about > > > > > > > > > ordering > > > > > > > > > > > > > > > > > > On Sat, 2 Nov 2019 at 23:07, Gabriel Belingueres < > > > > > > > belingue...@gmail.com> > > > > > > > > > > > > > > > > > > wrote: > > > > > > > > > > Hi: > > > > > > > > > > > > > > > > > > > > I just built maven core from source and found that it was > > > using > > > > > > > > > > StringSearchModelInterpolator instead of > > > > > > > StringVisitorModelInterpolator, > > > > > > > > > > > > > > > > > > a > > > > > > > > > > > > > > > > > > > regression from the last 3.6.2 release. > > > > > > > > > > > > > > > > > > > > I found that in > > > > > > > maven-model-builder/META-INF/sisu/javax.injected.Named > > > > > > > > > > file, both interpolators are listed but in reverse order > > > > (comparing > > > > > > > it > > > > > > > > > > > > > > > > > > with > > > > > > > > > > > > > > > > > > > the same file in 3.6.2), that is > > > StringSearchModelInterpolator > > > > > > appear > > > > > > > > > > > > > > > > > > first > > > > > > > > > > > > > > > > > > > in the file and StringVisitorModelInterpolator second. > > > > > > > > > > > > > > > > > > > > (I believe the dependency injection picks up the first > one > > it > > > > finds > > > > > > > with > > > > > > > > > > the right type.) > > > > > > > > > > > > > > > > > > > > Deleting the @Named annotation from > > > > StringSearchModelInterpolator > > > > > > > solved > > > > > > > > > > the issue, as this make the entry disappear from the > > > > > > > > > > javax.injected.Named > > > > > > > > > > file. Then the dependency injection uses the > > > > > > > > > > StringVisitorModelInterpolator. > > > > > > > > > > > > > > > > > > > > Can anyone confirm this issue? > > > > > > > > > > And if so, how to best prevent in the future that this > type > > > of > > > > > > > > > > dependency > > > > > > > > > > injection regressions from happening? > > > > > > > > > > > > > > > > > > > > Kind regards, > > > > > > > > > > Gabriel > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --------------------------------------------------------------------- > > > > > > > To unsubscribe, e-mail: dev-unsubscr...@maven.apache.org > > > > > > > For additional commands, e-mail: dev-h...@maven.apache.org > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --------------------------------------------------------------------- > > > > To unsubscribe, e-mail: dev-unsubscr...@maven.apache.org > > > > For additional commands, e-mail: dev-h...@maven.apache.org > > > > > > > > > > > > > >
