On 09.Jan.2003 -- 10:22 AM, Carsten Ziegeler wrote:
>
> Christian Haul wrote:
> >
> > On 09.Jan.2003 -- 09:28 AM, Carsten Ziegeler wrote:
> > > b) Chainers (?) are special components:
> > >
> > > <map:objects>
> > > <map:object name="request-param" ..../>
> > > <map:object name="session-attr" ..../>
> > > </map:objects>
> > > <map:object-chainers>
> > > <map:object-chainer name="my_chain ....>
> > > <first>request-param</first>
> > > <second>session-attr</second>
> > > ...
> > > </map:object>
> > > </map:object-chainers>
> > >
> > > And I can simply use {request-param:myname} and {my_chain:skin}
> > >
> > > Personally I would opt for a) because b) adds another component type
> > > to the sitemap that is not really needed and it might be confusing
> > > that {request-param:myname} is handled by an object component and
> > > {my_chain:skin} by an object-chainer.
> >
> > Right. AFAIK b) has never been proposed.
> >
> It has!
Really? Well, I don't think it's coming back :-)
>
> > BTW the real differences have been for the case where this 'pipeline'
> > in a) spans several stages.
> >
> Can you expand on this a little bit?
OK, the famous mapping example:
Suppose there are two sources: request parameters and a XML file. The
XML file contains default values. For reasons out of your control,
this file contains different keys than the names of the expected
request parameters. Thus a mapping needs to take place.
Note that lines with a "*)" comment could be inherited from the parent
or a central sitemap.
i) nest it
<map:objects>
<map:object name="request-param" ... /> <!-- *) -->
<map:object name="xmlfile" ... /> <!-- *) -->
<map:object name="map" ... /> <!-- *) -->
<map:object name="chain" ... >
<first name="request-param"/>
<second name="map" ...>
<prefix>/this/app/defaults/</prefix>
<use name="xmlfile"/>
</second>
</map:object>
</map:objects>
ii) construct from intermediates
<map:objects>
<map:object name="request-param" ... /> <!-- *) -->
<map:object name="xmlfile" ... /> <!-- *) -->
<map:object name="mymap" ... />
<prefix>/this/app/defaults/</prefix>
<use name="xmlfile"/>
</map:object>
<map:object name="chain" ... >
<first name="request-param"/>
<second name="mymap"/>
</map:object>
</map:objects>
Now, i) is clearer to me especially, as some declarations could be
inherited but ii) will produce slightly faster code. Today, both are
possible and can be mixed, which is good IMO.
Chris.
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C h r i s t i a n H a u l
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