[cdi-dev] [JBoss JIRA] (CDI-552) Add support for injection, decorators and interceptors on "new-ed" objects

[George Gastaldi (JIRA)]

    [ https://issues.jboss.org/browse/CDI-552?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13092748#comment-13092748 ] 

George Gastaldi commented on CDI-552:
-------------------------------------

CDI provides a  {{CDI.instance().select(MyBusinessService.class).get()}} to return an object with resolved injections. 
By using {{new}}, the lifecycle scope is no longer controlled by the CDI container so I am not sure CDI implementations can do that.

> Add support for injection, decorators and interceptors on "new-ed" objects
> --------------------------------------------------------------------------
>
>                 Key: CDI-552
>                 URL: https://issues.jboss.org/browse/CDI-552
>             Project: CDI Specification Issues
>          Issue Type: Epic
>          Components: Beans, Decorators, Interceptors, Resolution
>    Affects Versions: 2.0-EDR1
>            Reporter: Rogerio Liesenfeld
>
> The current CDI programming model is not friendly to object-oriented code or proper class design, and does not support true POJOs.
> With this I mean:
> 1) For object-oriented code, I need to be able to instantiate and use *stateful*, short-lived, objects, while still having @Inject fields in it. I shouldn't be forced to have a stateless (non-OO) class (ie, a [Transaction Script|http://martinfowler.com/eaaCatalog/transactionScript.html]).
> 2) Most classes in a business app are not meant to be used as subclasses, ie, they are not designed for extension; therefore, I should be able to make them {{final}} (see http://lcsd05.cs.tamu.edu/slides/keynote.pdf, page 26, or item 17 in the [book|http://www.amazon.com/Effective-Java-2nd-Joshua-Bloch/dp/0321356683]).
> 3) For a class to truly be a POJO, I must be able to make *full use* of the Java language when designing and implementing it; arbitrary constraints like "can't be final", "can't have final instance fields", "cannot be instantiated directly", etc. prevent it from being a "plain-old" Java object.
> Specifically, what I want is to be able to write the following in a JSF/CDI backing bean for a web UI:
> {code}
> MyBusinessService businessOp = new MyBusinessService(fieldFromUI1, fieldFromUI2, listWithMoreDataFromUI);
> businessOp.performSomeBusinessOperation(otherArgs);
> String result1 = businessOp.getResultXyz();
> List<result> moreResultData = businessOp.getFinalData();
> {code}
> ... while having MyBusinessService be a CDI bean containing one or more @Inject/@PersistenceContext fields (typically, an EntityManager and perhaps other service beans).
> Without this ability, application developers are forced to create procedural Transation Scripts (stateless service class, which tend to have low cohesion).
> For a CDI implementation to do this, it will need to use the java.lang.instrument API, like others tools (AspectJ, JBoss AOP, JBoss Byteman, JaCoCo, JMockit) already do.
> Also, for reference, the Spring framework already supports it for some time: http://docs.spring.io/spring/docs/3.0.0.M3/spring-framework-reference/html/ch08s08.html



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