[e4-dev] A missing framework piece: contexts?

[Oleg Besedin <obesedin@xxxxxxxxxx>]

“Progress is made by lazy men looking
for easier ways to do things”. 

I think this is exactly how the concept
of contexts came to life. Our code runs in some environment; way too often
we need to pass tens of arguments from method to method and from class
to class just to keep them aware of the environment. 

To make it easier we are considering
adding a concept of "context". At the conceptual level a "context"
is a combination of:
- a bag that could be stuffed with elements
that compose environment, and
- a mechanism to inject elements from
the bag into your POJO objects

The contexts are organized in a hierarchy.
Child context can add service objects that make sense at their level: 
        IEquinoxContext
 myContext = ApplicationContext.newChild();
        myContext.addObject("log",
myLog);

The service objects from the context
can be injected into POJO objects using field and method injection:

        myContext.injectInto(object)

resulting in the field object.equinoxLog
being set to "myLog". 

Contexts support dynamic events and
multiple service objects per ID. In addition, contexts can be tied into
creation of objects from the extension registry and help access OSGi services.

I'd like to raise this subject at the
E4 call to see what people think about it. The details of this work can
be found in the enhancement request 259423:

https://bugs.eclipse.org/bugs/show_bug.cgi?id=259423

Sincerely,
Oleg Besedin