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From Dmitri Plotnikov <dmi...@apache.org>
Subject Re: [JXPATH] Difference in introspection
Date Fri, 14 Jun 2002 21:34:46 GMT
Steve,

> > The idea of writing a custom JXPathBeanInfo is not that bad.
> > On the other
> > hand, I don't see why I could not update the introspector to
> > recursively
> > acquire property descriptors for all those parent interfaces.
>
> Yep, this would be nice. I wonder why the java.beans.Introspector()
doesn't
> provide this?  At this stage I have chosen to write a custom
JXPathBeanInfo
> that uses reflection to get a list of methods and then constructs a
> PropertyDescriptor for each.
I will do a similar thing tonight and check it in, because others may need
this functionality too.

> > The only issue with the use of the JXPathBeanInfo for the
> > interface is that
> > the _only_ properties available via the XPaths will be those on the
> > interface.  Any additional properties declared by the class
> > directly will be
> > inaccessible.
>
> I know. This is exactly what I want. I don't want to expose my entire
> internal API to the client, just a subset of it to ease maintenance and
> provide the client with a simplified more specific API. I control this in
a
> NOdePointerFactory impl - it checks the given Bean ojbect for a well-known
> XPath Interface (about 6 in total) and then uses the methods on the
matching
> XPath interface to create a BeanPointer. A little bit of work but worth
the
> effort.
Definitely makes sense to me now.  Very cool.

> Do you think this use-case of applying an "XPath API" could be applicable
to
> other developers? Definitely high on my list of requirements.
I don't know.  So far, you are the first.  If we hear the same requirement
from others, we should incorporate this solution into JXPath.

> steve.

- Dmitri

>
> >
> > Would it be possible to get JXPathBeanInfo for the object's
> > class, not the
> > interface?
> >
> > - Dmitri
> >
> > ----- Original Message -----
> > From: "Stephen Bartlett" <sbartlett@versata.com.au>
> > To: "'Jakarta Commons Developers List'"
> > <commons-dev@jakarta.apache.org>
> > Sent: Thursday, June 13, 2002 7:32 PM
> > Subject: RE: [JXPATH] Difference in introspection
> >
> >
> > > Dmitri,
> > >
> > > I have a NodePointerFactory impl that uses the JXPathIntrospector to
> > create
> > > a JXPathBeanInfo object for an Interface. I take it this is
> > incorrect
> > > usage??
> > >
> > > Looking at the code
> > JXPathBasicBeanInfo.getPropertyDEscriptors() tests for
> > > an Interface but the BeanInfo object returned by
> > > java.beans.Introspector.getBeanInfo() doesn't  recognizes
> > methods from
> > super
> > > interfaces even without a 'stop' class.
> > >
> > > I guess I could implement my own JXPathBeanInfo class that
> > uses reflection
> > > instead of JavaBeans to create PropertyDescriptors ?
> > >
> > > cheers,
> > > steve.
> > >
> > > > -----Original Message-----
> > > > From: Dmitri Plotnikov [mailto:dmitri@apache.org]
> > > > Sent: Thursday, 13 June 2002 10:42 PM
> > > > To: Jakarta Commons Developers List
> > > > Subject: Re: [JXPATH] Difference in introspection
> > > >
> > > >
> > > > Stephen,
> > > >
> > > > > Any reason why Interfaces are introspected differently Objects ?
> > > > >
> > > > > When an Interface is introspected "PropertyDescriptors" are
> > > > created only
> > > > for
> > > > > methods defined on the Interface and not for inherited
> > > > methods.  This is
> > > > not
> > > > > the case when an Object is introspected.
> > > > >
> > > > > Is this expected? I feel it is inconsistent and prevents me
> > > > from extending
> > > > > Interfaces.
> > > > JXPath is not supposed to introspect interfaces - just
> > > > JavaBeans.  How did
> > > > you get it to introspect an interface?
> > > >
> > > > Thanks,
> > > >
> > > > >
> > > > > Steve.
> > > >
> > > > - Dmitri
> > > >
> > > >
> > > > --
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