[webbeans-dev] Dynamic lookup

An issue that Bill brought up on the last concall, and that has been bothering me for a while is that we have a few different cases where the application wants to perform a dynamic lookup: (1) when binding types vary at runtime (2) when the dependency is optional (3) when you want to obtain an object that belongs to a child manager But the only way we let you do this is by injecting the Manager object, which has really evolved into an SPI-type integration point and has a whole bundle of operations that should not really be in the view of the application. Furthermore, it requires use of AnnotationLiteral for all binding types, which is pretty nasty. So I think we need to provide a different API, one that is more appropriate to usage by the application. Other solutions do have sugar for this: Guice has an injectable Provider<T> interface, Spring let's you write an abstract method which is implemented by the container. I think we should model a lookup interface on what we have for event firing. Analogous to: @Observable @SomeBinding Event<SomeEventType> someEvent; We should let you inject: @Obtainable @SomeBinding Instance<SomeType> someInstance; Which would let you call someInstance.get() to obtain an instance of the SomeType with SomeBinding. This would involve the following new interface: public interface Instance<T> { public T get(Annotation... bindings); public boolean isSatisfied(Annotation... bindings); } This is a *much* simpler API to use. The isDefined() method would let you determine if any Web Bean exists that satisfies the API type and bindings. -- Gavin King gavin.king(a)gmail.com http://in.relation.to/Bloggers/Gavin http://hibernate.org http://seamframework.org -- Gavin King gavin.king(a)gmail.com http://in.relation.to/Bloggers/Gavin http://hibernate.org http://seamframework.org