[jsr-314-open] [NEW - MR] Add ExpressionFactory to "11.4.6 Delegating Implementation Support"

[Pete Muir]

Hi all,

I would like to propose adding ExpressionFactory to the list of  
classes required to support the decorator pattern. This is to aid  
integration with CDI (JSR-299) implementations, which are require a  
callback when EL expression evaluation completes; the necessary hook  
into EL is via the ExpressionFactory. Adding ExpressionFactory to this  
list would make implemetors have to jump through fewer hoops to obtain  
the callback [1].

I propose this change to the MR so it can be used in the EE6 platform,  
the target for JSR-299.

Changes to spec required
-----------------------------------

* Add ExpressionFactory to the list of classes required to support the  
decorator pattern
* Add ExpressionFactoryWrapper class to support the decorator pattern

Changes to implementation required
--------------------------------------------------

* Add support for exposing and using wrapped ExpressionFactory

Impact on users and frameworks
--------------------------------------------

Users can now:

* call application.setExpressionFactory(new  
WebBeansExpressionFactory(application.getExpressionFactory());
* configure a wrapping expression factory in faces-config.xml
    <application>
        
<expressionFactory>org.jboss.webbeans.el.WebBeansExpressionFactory</ 
expressionFactory>
    </application>

[1] Currently this is possible by wrapping the application via the  
application factory and overriding the getExpressionFactory method