Re: Why not make listener events more generic

Geoff Longman wrote:

>Right now expressions that invoke listeners are like this:
>
>listeners.doSomething
>
>where doSomething is a method with the correct signature:
>
>public void doSomething(IRequestCycle cycle) throws RequestCycleException
>
>Why not extend this to make it possible to implement simple listeners
>directly in OGNL?
>i.e. make the expression the listener. I'm finding that I'm building pages
>using aggregation with beans
>more than extending a Page class these days. Would cut down on the code
>writing if I were able
>to manipulate my beans without declaring the listener methods.
>
>One could extend the OGNL context to contain the cycle as well as the
>component. This would
>allow one to replace the method declaration with simple expressions like:
>
>cycle.setPage("Home")
>beans.myBean.incrementCounter()
>
>etc.
>
>Any thoughts?
>  
>
Instead of having an event like "doSomething(IRequestCycle cycle)" 
implemented on an object why not have a generic one that will forward to 
an OGNL lambda expression?  This would allow you to not have to code up 
an entire class to implement a listener for simple cases like described 
above.  An OGNL lambda expression is an expression that is compiled to 
an AST that can then be executed at a later time.

Example:

    #myExpression = :[ doSomething() ]
    #myExpression(newRootObject)

Will cause doSomething to be called on newRootObject.  The calling 
syntax is NOT parameters; only one is allowed and it becomes the root 
object for the called expression.

- Drew

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< Drew Davidson | OGNL Technology >
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