Hi Stefan,I believe Optionals are not optimal for that.If a service is removed,
you would need a new empty optional instance. Optionals doesn't support to hold
a state. In addition to that you don't have callbacks where to get notified
about adding, modifying or removing a service. I could imagine, to get an
object similar to the promise injected, that supports the lifecycle callbacks,
as well as resolving, unresolving or re-resolving as well as handling
cardinality. A fluent API around the OSGi's ServiveTracker could be a solution.
Injecting Optional for just a subset of the supported cases in DS would, from
my perspective "pollute" the spec.Maybe you can realize a custom solution using
ServiceHooks?Regards,Mark Hoffmann M.A. Dipl.-Betriebswirt (FH) CEO/CTO Phone:
+49 3641 384 910 0 Mobile: +49 175 701 2201 E-Mail:
m.hoffm...@data-in-motion.biz Web: www.datainmotion.de Data In Motion
Consulting GmbH Kahlaische Strasse 4 07745 Jena Germany Geschäftsführer/CEO
Mark Hoffmann Jürgen Albert Jena HRB 513025 Steuernummer 162/107/05779 USt-Id
DE310002614
-------- Ursprüngliche Nachricht --------Von: Stefan Bischof via osgi-dev
<osgi-dev@mail.osgi.org> Datum: 22.09.20 15:48 (GMT+01:00) An:
osgi-dev@mail.osgi.org Betreff: [osgi-dev] SCR: ServiceInjection into Fields
that are Optional<Service>
Hi,
I like it to use Optionals if it is possible that a field could
be null.
In context of OSGi Services with SCR that means I have to handle
it like this:
```
@Component
public class MyComponent
{
Optional<Foo> oFoo = Optional.empty();
@Reference(cardinality = ReferenceCardinality.OPTIONAL)
void bindFoo(Foo foo)
{
oFoo = Optional.of(foo);
}
}
```
What I really want to do is this:
```
@Component
public class MyComponent
{
@Reference
Optional<Foo> oFoo;
}
```
We have something like this in OSGi - CDI Integration Specification
https://youtu.be/7-UUJ4WkMsg?t=839
It would be nice to have this feature with the new version of the
R8 DS Spec.
Regards
Stefan
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