<HTML><BODY>Hi Martin<br><br>Thank you very much for your comment and suggestion about improving.<br><br>Best regards, Alex<br><br><br><blockquote style="border-left:1px solid #0857A6; margin:10px; padding:0 0 0 10px;">
Четверг, 31 августа 2017, 12:50 +03:00 от Martin Kouba <mkouba@redhat.com>:<br>
<br>
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<div id="style_15041730570000000403_BODY">Hi Alex,<br>
<br>
1) should work but looks a little bit cumbersome. WRT 2) you should <br>
avoid using BeanManager to create a bean instance whenever possible. And <br>
in this particular case, if SimpleFoo is @Dependent it wouldn't be <br>
destroyed correctly (@PreDestroy) when Parent or Child is destroyed.<br>
<br>
The following should also work (no need to have two Instance IPs):<br>
<br>
public class Parent {<br>
<br>
@Inject<br>
private Instance<SimpleFoo> fooInstance;<br>
<br>
private SimpleFoo foo;<br>
<br>
protected SimpleFoo newFoo() {<br>
return fooInstance.get();<br>
}<br>
<br>
@PostConstruct<br>
private void doPostConstruct() {<br>
foo = newFoo();<br>
}<br>
}<br>
<br>
public class Child extends Parent {<br>
<br>
@Override<br>
protected AdvancedFoo newFoo() {<br>
return fooInstance.select(AdvancedFoo.class).get();<br>
}<br>
}<br>
<br>
<br>
Martin<br>
<br>
Dne 31.8.2017 v 11:07 Alex Sviridov napsal(a):<br>
> Hi Martin,<br>
> <br>
> <br>
> Could you comment the following solutions?<br>
> <br>
> 1)<br>
> public class Parent {<br>
> <br>
> @Inject<br>
> private Instance<SimpleFoo> fooInstance;<br>
> <br>
> private SimpleFoo foo;<br>
> <br>
> protected SimpleFoo newFoo() {<br>
> return fooInstance.get();<br>
> }<br>
> <br>
> @PostConstruct<br>
> private void doPostConstruct() {<br>
> foo = newFoo();<br>
> }<br>
> }<br>
> <br>
> public class Child extends Parent {<br>
> <br>
> @Inject<br>
> private Instance<AdvancedFoo> fooInstance;<br>
> <br>
> @Override<br>
> protected AdvancedFoo newFoo() {<br>
> return fooInstance.get();<br>
> }<br>
> }<br>
> <br>
> <br>
> 2)<br>
> <br>
> public class Parent {<br>
> <br>
> @Inject<br>
> protected BeanManager beanManager;<br>
> <br>
> private SimpleFoo foo;<br>
> <br>
> protected SimpleFoo newFoo() {<br>
> SimpleFoo foo = constructing bean with BM;<br>
> return foo;<br>
> }<br>
> <br>
> @PostConstruct<br>
> private void doPostConstruct() {<br>
> foo = newFoo();<br>
> }<br>
> }<br>
> <br>
> public class Child extends Parent {<br>
> <br>
> @Override<br>
> protected AdvancedFoo newFoo() {<br>
> AdvancedFoo foo = constructing bean with BM;<br>
> return foo;<br>
> }<br>
> }<br>
> <br>
> <br>
> Best regards, Alex<br>
> <br>
> Среда, 30 августа 2017, 10:51 +03:00 от Matej Novotny<br>
> <<a href="mailto:manovotn@redhat.com">manovotn@redhat.com</a> <mailto:<a href="mailto:manovotn@redhat.com">manovotn@redhat.com</a>>>:<br>
> <br>
> 1) If you inject Instance<T>, you still have the ambiguous<br>
> dependency issue for any class which does have a subclass.<br>
> E.g. from your sample:<br>
> <br>
> @Inject<br>
> Instance<SimpleFoo> instance;<br>
> <br>
> //within some method<br>
> instance.get(); -> this will blow up because you have two beans<br>
> which have SimpleFoo type (SimpleFoo and AdvancedFoo)<br>
> <br>
> 2) I don't understand what you mean by this. How does BM help here?<br>
> <br>
> <br>
> Sidenote:<br>
> You might want to try and use what Martin said - limiting the types<br>
> of a bean with @Typed(MyClass.Foo).<br>
> That way you have control over the bean types and can further<br>
> manupulate the injection.<br>
> Limit all your children to only the actual subclass type they have:<br>
> <br>
> @Dependent<br>
> @Typed(AdvancedFoo.class)<br>
> public class AdvancedFoo extends SimpleFoo {<br>
> // this ben now only has a bean of AdvancedFoo, e.g. it does not<br>
> fit into injection point for SimpleFoo<br>
> }<br>
> <br>
> And then override the initializer methods like this:<br>
> <br>
> @Dependent<br>
> public class Parent extends Child {<br>
> <br>
> @Inject<br>
> @Override<br>
> protected void setFoo(AdvancedFoo foo) {<br>
> this.foo = foo; // assuming foo is a protected field<br>
> }<br>
> }<br>
> <br>
> Matej<br>
> <br>
> <br>
> ----- Original Message -----<br>
> > From: "Alex Sviridov" <<a href="mailto:ooo_saturn7@mail.ru">ooo_saturn7@mail.ru</a><br>
> <mailto:<a href="mailto:ooo_saturn7@mail.ru">ooo_saturn7@mail.ru</a>>><br>
> > To: "weld-dev" <<a href="mailto:weld-dev@lists.jboss.org">weld-dev@lists.jboss.org</a><br>
> <mailto:<a href="mailto:weld-dev@lists.jboss.org">weld-dev@lists.jboss.org</a>>><br>
> > Sent: Tuesday, August 29, 2017 8:54:47 PM<br>
> > Subject: Re: [weld-dev] How to make method injection when bean<br>
> subclass is required in Weld?<br>
> ><br>
> > I thought here, and would like to share my ideas hoping to get<br>
> comments from<br>
> > more experienced people.<br>
> ><br>
> > First of all I came to conclusion that CDI works badly with cases<br>
> when we<br>
> > need<br>
> > to change field values in super classes. If there is a lot of<br>
> inheritance as<br>
> > in my case:<br>
> > ParentA, ChildA0, ChildA1.., ParentB, ChildB0, ChildB1..,... then<br>
> situation<br>
> > is<br>
> > becoming very bad. Maybe in future there will be other solutions<br>
> in CDI<br>
> > specs.<br>
> ><br>
> > I found two additional ways that can be used. 1) Inject not beans but<br>
> > instances,<br>
> > + method SimpleFoo newFoo {return Instance<SimpleFoo>.get} +<br>
> overriding.<br>
> > 2) Inject BeanManager + method SimpleFoo newFoo() {beanManager...} +<br>
> > overriding.<br>
> ><br>
> > Maybe such ways can be named lazy/postponed initialization with<br>
> overriding<br>
> > support....<br>
> ><br>
> > Best regards, Alex<br>
> ><br>
> ><br>
> ><br>
> ><br>
> > Вторник, 29 августа 2017, 18:22 +03:00 от Martin Kouba<br>
> <<a href="mailto:mkouba@redhat.com">mkouba@redhat.com</a> <mailto:<a href="mailto:mkouba@redhat.com">mkouba@redhat.com</a>>>:<br>
> ><br>
> > Hi Alex,<br>
> ><br>
> > that's an interesting question. Indeed, qualifiers are the way to<br>
> go if<br>
> > you need to keep the method signature.<br>
> ><br>
> > Another way could be to override the setFoo() method so that the<br>
> Child<br>
> > initializer is ignored and add a new method to inject AdvancedFoo:<br>
> ><br>
> > @Override<br>
> > protected void setFoo(SimpleFoo foo) { // Do nothing }<br>
> ><br>
> > @Inject<br>
> > void setAdvancedFoo(AdvancedFoo foo) {<br>
> > super.setFoo(foo);<br>
> > }<br>
> ><br>
> > However, note that right now there are the following beans:<br>
> ><br>
> > SimpleFoo with bean types Object, SimpleFoo<br>
> > AdvancedFoo -> Object, SimpleFoo, AdvancedFoo<br>
> ><br>
> > So if you do @Inject SimpleFoo you get ambiguous dependency exception<br>
> > because both SimpleFoo and AdvancedFoo are eligible for injection.<br>
> ><br>
> > To resolve this you need to use qualifiers or restrict the bean<br>
> types of<br>
> > AdvancedFoo:<br>
> ><br>
> > @Typed(AdvancedFoo.class)<br>
> > class AdvancedFoo extends SimpleFoo {}<br>
> ><br>
> > HTH<br>
> ><br>
> > Martin<br>
> ><br>
> ><br>
> > Dne 29.8.2017 v 15:09 Matej Novotny napsal(a):<br>
> > > Hi Alex,<br>
> > ><br>
> > > no need to be sorry, you have come to the right place :)<br>
> > > As for your question, the simplest thing is probably to use<br>
> qualifiers.<br>
> > ><br>
> > > Create your own like this:<br>
> > ><br>
> > > @Qualifier<br>
> > > @Retention(RetentionPolicy.RUNTIME)<br>
> > > @Target({ ElementType.TYPE, ElementType.PARAMETER,<br>
> ElementType.FIELD,<br>
> > > ElementType.METHOD })<br>
> > > public @interface MyQualifier {}<br>
> > ><br>
> > ><br>
> > > And then change your AdvancedFoo class to use the qualifier:<br>
> > ><br>
> > > @Dependent<br>
> > > @MyQualifier<br>
> > > public class AdvancedFoo extends SimpleFoo {<br>
> > > }<br>
> > ><br>
> > > And accordingly, the init method which uses injection should<br>
> then look like<br>
> > > this:<br>
> > ><br>
> > > @Dependent<br>
> > > public class Parent extends Child {<br>
> > ><br>
> > > @Inject<br>
> > > @Override<br>
> > > protected void setFoo(@MyQualifier SimpleFoo foo) {<br>
> > > super.setFoo(foo);<br>
> > > }<br>
> > > }<br>
> > ><br>
> > > Does this answer your question?<br>
> > ><br>
> > > Matej<br>
> > ><br>
> > > ----- Original Message -----<br>
> > >> From: "Alex Sviridov" < <a href="mailto:ooo_saturn7@mail.ru">ooo_saturn7@mail.ru</a><br>
> <mailto:<a href="mailto:ooo_saturn7@mail.ru">ooo_saturn7@mail.ru</a>> ><br>
> > >> To: "weld-dev" < <a href="mailto:weld-dev@lists.jboss.org">weld-dev@lists.jboss.org</a><br>
> <mailto:<a href="mailto:weld-dev@lists.jboss.org">weld-dev@lists.jboss.org</a>> ><br>
> > >> Sent: Tuesday, August 29, 2017 1:46:23 PM<br>
> > >> Subject: [weld-dev] How to make method injection when bean<br>
> subclass is<br>
> > >> required in Weld?<br>
> > >><br>
> > >> Hi all,<br>
> > >><br>
> > >> I am really sorry for writing to this mailing list, but I<br>
> checked all user<br>
> > >> forums and chats and saw that they are very old.<br>
> > >><br>
> > >> I would be very thankful if someone gives suggestion for<br>
> solving the<br>
> > >> following problem.<br>
> > >> I have a child and parent class. Child has SimpleFoo, Parent<br>
> needs Advaced<br>
> > >> foo. So,<br>
> > >><br>
> > >> @Dependent<br>
> > >> public class SimpleFoo {<br>
> > >> }<br>
> > >><br>
> > >> @Dependent<br>
> > >> public class AdvancedFoo extends SimpleFoo {<br>
> > >> }<br>
> > >><br>
> > >> @Dependent<br>
> > >> public class Child {<br>
> > >><br>
> > >> private SimpleFoo foo;<br>
> > >><br>
> > >> @Inject<br>
> > >> protected void setFoo(SimpleFoo foo) {<br>
> > >> this.foo = foo;<br>
> > >> }<br>
> > >> }<br>
> > >><br>
> > >> @Dependent<br>
> > >> public class Parent extends Child {<br>
> > >><br>
> > >> @Inject<br>
> > >> @Override<br>
> > >> protected void setFoo(SimpleFoo foo) { //How to inject here<br>
> AdvancedFoo?<br>
> > >> super.setFoo(foo);<br>
> > >> }<br>
> > >> }<br>
> > >><br>
> > >> How to inject in Parent AdvancedFoo? I know that I can do it via<br>
> > >> constructor<br>
> > >> injection<br>
> > >> but I need method injection. How to do it? Can it be done<br>
> without using<br>
> > >> names<br>
> > >> (like MyBean1)<br>
> > >> but only using classes (AdvancedFoo)?<br>
> > >><br>
> > >> Best regards, Alex<br>
> > >><br>
> > >><br>
> > >><br>
> > >><br>
> > >><br>
> > >> --<br>
> > >> Alex Sviridov<br>
> > >><br>
> > >> _______________________________________________<br>
> > >> weld-dev mailing list<br>
> > >> <a href="mailto:weld-dev@lists.jboss.org">weld-dev@lists.jboss.org</a> <mailto:<a href="mailto:weld-dev@lists.jboss.org">weld-dev@lists.jboss.org</a>><br>
> > >> <a href="https://lists.jboss.org/mailman/listinfo/weld-dev" target="_blank">https://lists.jboss.org/mailman/listinfo/weld-dev</a><br>
> > > _______________________________________________<br>
> > > weld-dev mailing list<br>
> > > <a href="mailto:weld-dev@lists.jboss.org">weld-dev@lists.jboss.org</a> <mailto:<a href="mailto:weld-dev@lists.jboss.org">weld-dev@lists.jboss.org</a>><br>
> > > <a href="https://lists.jboss.org/mailman/listinfo/weld-dev" target="_blank">https://lists.jboss.org/mailman/listinfo/weld-dev</a><br>
> > ><br>
> ><br>
> > --<br>
> > Martin Kouba<br>
> > Senior Software Engineer<br>
> > Red Hat, Czech Republic<br>
> ><br>
> ><br>
> > _______________________________________________<br>
> > weld-dev mailing list<br>
> > <a href="mailto:weld-dev@lists.jboss.org">weld-dev@lists.jboss.org</a> <mailto:<a href="mailto:weld-dev@lists.jboss.org">weld-dev@lists.jboss.org</a>><br>
> > <a href="https://lists.jboss.org/mailman/listinfo/weld-dev" target="_blank">https://lists.jboss.org/mailman/listinfo/weld-dev</a><br>
> <br>
> <br>
> <br>
> ------------------------------------------------------------------------<br>
> <br>
> -- <br>
> Alex Sviridov<br>
<br>
-- <br>
Martin Kouba<br>
Senior Software Engineer<br>
Red Hat, Czech Republic<br>
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</blockquote>
<br>
<br>-- <br>Alex Sviridov<br></BODY></HTML>