Dmitry Gusev created TAP5-2637:
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Summary: Provide API to query multiple/all service instances from
ObjectLocator by service interface/markers
Key: TAP5-2637
URL: https://issues.apache.org/jira/browse/TAP5-2637
Project: Tapestry 5
Issue Type: Improvement
Components: tapestry-ioc
Reporter: Dmitry Gusev
Tapestry IoC's `ObjectLocator` can only return a service if there's exactly one
implementation matching criteria:
{code:java}
<T> T getService(Class<T> serviceInterface)
<T> T getService(Class<T> serviceInterface, Class<? extends Annotation>...
markerTypes);
{code}
It's sometimes necessary to get all registered services, i.e. when integrating
with 3rd party libraries that support "bring your own service discovery", they
expect this functionality from service discovery.
At present `RegistryImpl` has everything we need to implement this feature, see
`#findServiceIdsForInterface` and `#findServiceDefsMatchingMarkerAndType`.
As future work we could also support list-type injections, i.e.
{code:java}
@Inject List<ServiceA> multipleInjections;{code}
Marker annotations would fit nicely here, e.g. `@Inject @Blue List<ServiceA>
multipleInjections;`
In theory it may break injections for services that implement the `List`
interface itself, unsure if there are any real use-cases for it. But as all
service definitions are known upfront on registry initialisation we may
implement a safety check and fail with error if there's any. We may also
provide a symbol to disable List-injections, and only run the mentioned
check/failure if the symbol is enabled.
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