Pierre De Rop created FELIX-5996:
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Summary: Remove generic parameter in DM Component interface
Key: FELIX-5996
URL: https://issues.apache.org/jira/browse/FELIX-5996
Project: Felix
Issue Type: Task
Components: Dependency Manager
Affects Versions: org.apache.felix.dependencymanager-r13
Reporter: Pierre De Rop
Assignee: Pierre De Rop
Since dm-r13, the Component interface is now taking a generic parameter so it
make it easier to define extended components like adapters.
So, with this new model, it looks like the following:
{code:java}
public interface Component<T extends Component<T>> {
T setInterface(String service, Dictionary properties)
T setImplementation(Object ob);
...
}
public interface AdapterComponent extends Component<AdapterComponent> {
AdapterComponent setAdaptee(Class<?> service, String filter);
AdapterComponent setAdapteeCallbacks(String add, String change, String
remove, String swap);
...
}
{code}
and you can now do something like this:
{code:java}
Component adapter = createAdapterComponent()
.setAdaptee(Adaptee.class, "(foo=bar)")
.setAdapteeCallbacks("setAdaptee", "changeAdaptee", null, null)
.setImplementation(AdapterImpl.class)
.setInterface(AdapterService.class, null)
.add(createServiceDependency().setService(LogService.class));
{code}
now, while using the generic parameter simplify the declaration of component
adapters, it has a drawback: the Component now takes a generic parameter, and
old code using simple components now generates a compilation warning:
{code:java}
Component adapter = createComponent()
.setImplementation(SimpleComponent.class)
...
{code}
so, the above example generates a compilation warning, and you now have to
declare "?" in order to get rid of the warning:
{code:java}
Component<?> adapter = createComponent()
.setImplementation(SimpleComponent.class)
...
{code}
that being said, maybe we can refactor in order to get rid of the generic
parameter, by copying the top level component methods in sub interfaces, like
this:
{code:java}
public interface Component {
Component setInterface(String service, Dictionary properties);
Component setImplementation(Object ob);
...
}
public interface AdapterComponent extends Component
{ // Component methods with specialized signatures AdapterComponent
setInterface(String service, Dictionary properties) AdapterComponent
setImplementation(Object ob); … // AdapterComponent methods AdapterComponent
setAdaptee(Class<?> service, String filter); AdapterComponent
setAdapteeCallbacks(String add, String change, String remove, String swap);
{code}
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