[cdi-dev] [JBoss JIRA] (CDI-45) Optional Injection Points

[Antonin Stefanutti (JIRA)]

    [ https://issues.jboss.org/browse/CDI-45?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12997578#comment-12997578 ] 

Antonin Stefanutti edited comment on CDI-45 at 9/1/14 5:14 PM:
---------------------------------------------------------------

Then one potential compromise would be to enrich the existing abstractions, either {{Instance}} or {{Provider}} with the equivalent semantic that of {{Optional}}. For example:
{code}
@Inject
Provider<MyBean> bean;

if (bean.isPresent())
    bean.get();
{code}
Or if we think {{Optional}} is a convenient abstraction:
{code}
@Inject
Provider<MyBean> bean;

bean.getOptional();
{code}
In any case, I think that a {{isSatisfied()}} / {{isResolvable()}} method is missing on the {{Instance}} interface when alternatives are enabled for example and that would avoid writing {{!isUnsatisfied() && !isAmbiguous()}}.

As per backward compatibility for these interfaces, are they really meant to be implemented aside from the implementations? That would avoid introducing another interface. If not maybe default method in Java 8 could help.


was (Author: stefanutti):
Then one potential compromise would be to enrich the existing abstractions, either {{Instance}} or {{Provider}} with the equivalent semantic that of {{Optional}}. For example:
{code}
@Inject
Provider<MyBean> bean;

if (bean.isPresent())
    bean.get();
{code}
In any case, I think that a {{isSatisfied()}} / {{isResolvable()}} method is missing on the {{Instance}} interface when alternatives are enabled for example and that would avoid writing {{!isUnsatisfied() && !isAmbiguous()}}.

As per backward compatibility for these interfaces, are they really meant to be implemented aside from the implementations? That would avoid introducing another interface. If not maybe default method in Java 8 could help.

> Optional Injection Points
> -------------------------
>
>                 Key: CDI-45
>                 URL: https://issues.jboss.org/browse/CDI-45
>             Project: CDI Specification Issues
>          Issue Type: Feature Request
>          Components: Resolution
>    Affects Versions: 1.0
>            Reporter: Stuart Douglas
>             Fix For: 2.0 (discussion)
>
>
> There are occoasions where it may be useful for some injection points to be optional, e.g.
> @Inject
> @Optional 
> MyBean bean; 
> This would behave the same as a normal injection point, however it will not cause the deployment to fail if it is not satisified. 



--
This message was sent by Atlassian JIRA
(v6.3.1#6329)