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From "Stephen Colebourne" <scolebou...@eurobell.co.uk>
Subject Re: [BeanUtils] PropertyUtils and DynaBeans (getPropertyDescriptors)
Date Thu, 18 Apr 2002 20:27:09 GMT
Yes, keeping it separate makes sense to me.
Let me explain my interest in this area. At joda.org (and for my day job) I
have been developing classes to manage domain models. Part of this work has
involved defining classes that provide bean meta data, similar to DynaClass
and PropertyDescriptor and bean property access. Also built is code to query
the object model using XPath backed by Jaxen. On my todo list was an
implementation of the JEL syntax. I hadn't decided if that should be done as
a plugin to Jaxen, or from scratch.

So two things are in my mind.
1) Can I reuse the (forthcoming) JEL implementation from commons?
2) Could the joda work potentially form the basis for the new commons
component that James describes?

Stephen

From: Craig R. McClanahan <craigmcc@apache.org>
> I agree with keeping expression evaluation separate from DynaBeans.  Not
> only does this provide for consistency (what method on a standard JavaBean
> knows how to interpret "one.two[3].four(5)" :-), but different
> applications might want to use different expression language syntaxes --
> and baking a particular one into the beans themselves would really hamper
> this.
>
> Craig
>
>
> On Thu, 18 Apr 2002, James Strachan wrote:
>
> > Date: Thu, 18 Apr 2002 13:07:56 +0100
> > From: James Strachan <james_strachan@yahoo.co.uk>
> > Reply-To: Jakarta Commons Developers List
<commons-dev@jakarta.apache.org>
> > To: Jakarta Commons Developers List <commons-dev@jakarta.apache.org>
> > Subject: Re: [BeanUtils] PropertyUtils and DynaBeans
> >     (getPropertyDescriptors)
> >
> > From: "James Strachan" <james_strachan@yahoo.co.uk>
> > > ----- Original Message -----
> > > From: "Stephen Colebourne" <scolebourne@eurobell.co.uk>
> > > > This is what I was getting at. If DynaBeans were to become used as
the
> > > main
> > > > interface (instead of PropertyUtils), then DynaBeans would need to
> > support
> > > > this notation.
> > >
> > > I think DynaBeans is a great abstraction for DynaBeans and regular
beans.
> > > DynaBeans can handle
> > >
> > > * regular properties via get(String name)
> > > * indexed properties via get(String name, int index);
> > > * mapped properties via get(String name, String key);
> > >
> > > Where DynaBeans are maybe not the best abstraction right now is for
> > complex
> > > expressions like one.two[3].four(5).
> >
> > Incidentally, there's an expression language I refer to as JEL (Java
> > Expression Language) - I'm hoping the name catches on like JSTL did ;-).
Its
> > used in JSTL, will be native in JSP soon and I think JSF uses it too.
Its
> > quite similar to a superset of the expression language currently
supported
> > by beanutils. Right now it exists in the JSTL reference implementation
over
> > at jakarta-taglibs in the 'standard' taglib and hopefully its gonna move
> > over to jakarta commons sometime soon.
> >
> > When JEL moves over here, we're gonna have a seperate commons component
for
> > parsing and evaluating complex expressions on beans, Maps, Lists, arrays
> > (and hopefully DynaBeans too). So maybe its a good idea to consider
> > expression languages as being logically seperate from an 'introspection
> > wrapper'.  i.e. that DynaBeans can be used as a great wrapper around
> > introspection while supporting new features like mapped properties and
> > DynaBeans themselves too and that expression languages should be used
> > seperately, either via the API in beanutils right now or the JEL which
will
> > arrive here later.
> >
> > Does that sound a reasonable strategy?
> >
> > James



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