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From "Kris Nuttycombe" <>
Subject Re: [beanutils] PropertyUtils & DynaBeans
Date Mon, 06 Dec 2004 17:31:53 GMT
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.


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.
>----- Original Message ----- 
>From: "Kris Nuttycombe" <>
>To: "Commons Developers Jakarta" <>
>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?
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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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