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From robert burrell donkin <robertburrelldon...@blueyonder.co.uk>
Subject Re: [betwixt] Inheritance version 2
Date Tue, 01 Jun 2004 19:52:36 GMT
i have an idea what's causing this but i need to get the commons 
logging release candidate signed and shipped tonight so it'll have to 
be tomorrow.

- robert

On 1 Jun 2004, at 12:31, Inger, Matthew wrote:

> One of the things i've run into in my refactoring is this:
>
> I've create a utility class to add the inherited descriptors
> to an XMLBeanInfo class:
>
> 	public static void addInheritance(XMLBeanInfoRegistry registry,
>                XMLBeanInfo info,
>                InheritType type);
>
> where InheritType is an enumerated style class.
>
> However, when i make a call in the InfoRule to:
>
> getXMLInfoDigester().getXMLIntrospector(), this comes
> up as null when running the test cases, and thus i get
> a null pointer exception when trying to get the
> registry from there.  I can send you the details later,
> as i don't have the code available at this moment (it's at home).
>
> It doesn't seem right that the introspector is null.  In a real
> scenario, this would always be set, correct?
>
> The reason i expect the registry is so that the user can pick and
> choose the inheritance they want.  If A extends B extends C,
> then they would first have to add the inheritance from C to B,
> and then from B to A (as they would with the XML).  In order to
> get full inheritance.
>
> But to get the full inheritance in that case, we need to use the
> same registry instance.
>
> Any suggestions?
>
> -----Original Message-----
> From: robert burrell donkin
> [mailto:robertburrelldonkin@blueyonder.co.uk]
> Sent: Sunday, May 30, 2004 6:53 AM
> To: Jakarta Commons Developers List
> Subject: Re: [betwixt] Inheritance version 2
>
>
>
> On 30 May 2004, at 06:14, Inger, Matthew wrote:
>
>> The other question is, is this the right approach?
>
> betwixt is the sort of component where users appreciate different ways
> to achieve the same goals. i've been often surprised by innovative uses
> such features have been put to.
>
> so, the question i usually ask myself is: is this a reasonable
> approach? if so, then that's usually good enough for me.
>
>> It is an XML only solution, and would require the
>> user to do this manually if building their mapping
>> in code (does anyone ever do this?),
>
> yes. there are some very powerful tricks you can do by rolling your own
> descriptors.
>
>> or when just
>> introspecting without a mapping of any sort.
>> Perhaps a utility class to do the inheritance,
>> along with another method on the introspector
>> to allow them to introspect and include inheritance
>> might be in order.  I will explore this.
>
> it usually works out that you want this as well. in the end, though, it
> usually ends up that you want a pluggable strategy on introspector so
> that users can programmatically choose which classes should inherit. so
> it's probably best going straight for that. it's best to implementation
> the logical strategy interface as an abstract class (since methods can
> then be added without breaking backwards compatibility.
>
> - robert
>
>
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