Bug 331746

Comment 1 Oleg Besedin 2010-12-03 09:50:28 EST

Sorry, I don't understand this.

We are not changing how extension registry work. I'd like to do taht, but that is out of scope for the 4.1. Extension registry functionality remains unchanged between 3.x and 4.0/4.1.

If you are saying that it would be nice to customize objects created in DI, then I totally agree; moreover, we alcready provide this functionality.

In a simple example:

class MyPart { 
  @Inject
  public MyPart(Component parent, ModelService s) {
     ....
  }
} 

you can also add "@PostConstruct" method to "finalize" creation/injection process:

class MyPart { 
  @Inject
  public MyPart(Component parent, ModelService s) {
     ....
  }

  @PostConstruct
  public void init(@Optional ISelection initialSelection) {
     ....
  }
} 

you can have a factory classes by using IBinding:

InjectorFactory.getDefault().addBinding(MyPart.class).implementedBy(MyFactory.class)

or using ContextFunctions:

public class MyFactory extends ContextFunction {
 public Object compute(IEclipseContext context) {
  MPart result = ContextInjectionFactory.make(MyPart.class, context);
  doWhatever(result);
  return result;
}

Is there something missing?

(Note: factory functions are a bit more "advanced" topic and related APIs might change.)

Comment 2 Sven Efftinge 2010-12-03 10:36:45 EST

E4 replaces a couple of extension points with the workbench model. E.g. action handlers are now contributed by the means of a workbench model snippet (or whatever you call it).

In Equinox the bundle where the contribution comes from can take care of the creation and initialization of objects. This is not possible in e4.

I suggest to allow to declare a factory instead of the actual type, such that e4 creates the factory and after that calls a certain method in order to obtain the real contributed object (e.g. action handler).

Some of the comments in Bug 331556 might help to understand my enhancement request.

Comment 3 John Arthorne 2010-12-03 10:48:33 EST

I think the only thing missing is the magic line at the end, that checks if the constructed object is actually a factory, in which case it is replaced with the real part. This is the corresponding line in the extension registry:

// Deal with executable extension factories.
if (result instanceof IExecutableExtensionFactory)
	result = ((IExecutableExtensionFactory) result).create();

I don't think there is a corresponding place in e4 where the contributed object can be replaced. I imagine a simple change in somewhere like InjectorImpl#internalMake:

if (newInstance instanceof FactoryObject)
  newInstance = ((FactoryObject)newInstance).create();

I.e., we actually perform our injection into a factory object, which then creates the real object.

Comment 4 Paul Webster 2012-01-04 08:09:02 EST

Can we look at this in M5?

PW

Comment 5 John Arthorne 2012-04-24 11:11:02 EDT

Please review target milestone and bump to > 4.2 if appropriate.