The main issue is that my code needs to perform bean introspection on an
Object without knowing whether that object is a regular bean or a
DynaBean. Sure, I could add a clause like you suggest everywhere I want
to do this, but it seems like this is really something that should be
handled in PropertyUtils so that introspection information can be
cached. The system I'm working on processes tens of thousands of objects
at a pass, so creating a new WrapDynaBean for each object when a lookup
on the classlass would suffice seems excessive.
Kris
Niall Pemberton wrote:
Maybe you could spell out the issues with PropertyUtils and DynaBeans and
the methods involved and what you're trying to do because its not clear what
your trying to resolve.
I'm don't see much value in the getDynaProperties() method being in
PropertyUtils - all you need to do is make eveything a DynaBean then you can
get the DynaProperties and do whatever you want using the existing
DynaBean/DynaClass methods - no need for PropertyUtils at all.
DynaBean dynaBean = (bean instanceof DynaBean)
? (DynaBean)bean : new WrapDynaBean(bean);
For caching to work people are going to have to change how they create
DynaBeans and I believe its better left up to the environment they're being
used in to implement a caching mechanism - Struts does this for its
DynaActionForm implementation.
Niall
----- Original Message -----
From: "Kris Nuttycombe" <[EMAIL PROTECTED]>
To: "Commons Developers Jakarta" <[EMAIL PROTECTED]>
Sent: Saturday, December 04, 2004 12:55 AM
Subject: [beanutils] PropertyUtils & DynaBeans
Hi, all,
As it currently stands, PropertyUtils doesn't support DynaBeans for a
number of its methods. It doesn't make much sense to return
PropertyDescriptors for DynaBeans, but it's no great pain to use
WrapDynaClass on an ordinary class and thereby be able to introspect
either regular beans or DynaBeans using the same interface. To support
this, I'd like to add a method with the signature:
DynaProperty[] getDynaProperties(Object bean)
to PropertyUtilsBean, with a corresponding static method in PropertyUtils.
Now, one of the other advantages of using PropertyUtilsBean is that it
caches the introspected data. Conceivably, this would also be a useful
feature for the getDynaProperties method. However, here we have a
problem: since DynaClass doesn't have any way to enforce that its
implementations implement HashCode, there's no way to use the same map
caching strategy as is used for the PropertyDescriptors. This
illustrates a larger issue, which is that DynaClass objects aren't
singletons like Class objects are.
To resolve this, I propose adding an AbstractDynaClass base class that
implements hashCode() and equals() based upon the public methods
available in DynaClass. This way, even if DynaClasses aren't singletons,
they can be used for hash keys. It might be also useful to implement a
registry for DynaClasses in this abstract class to provide
singleton-like functionality. Existing DynaClass implementations would
be modified to extend AbstractDynaClass.
Any thoughts?
Kris
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=====================================================
Kris Nuttycombe
Associate Scientist
Geospatial Data Services Group
CIRES, National Geophysical Data Center/NOAA
(303) 497-6337
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