[XML-SIG] xmlpickle.py ?!

[M.-A. Lemburg]

Mike Olson wrote:
> 
> "M.-A. Lemburg" wrote:
> >
> > Mike Olson wrote:
> > >
> > > "M.-A. Lemburg" wrote:
> > > >
> > >
> > > You may want to look at Zope in Zope/lib/python/ZODB/ImportExport.py.
> > > they do some XML pickling here.  However, I think they call back to each
> > > object for help in the pickle processes (each object writes thier own
> > > chunk of XML).  Though I'm not 100% sure.
> >
> >
> > BTW, I only have a vague idea about what Xpath et al. do
> > except that they are intended to address certain parts in
> > an XML file. Is there anything to watch out for when designing
> > a DTD in order to make addressability simple with Xpath ?
> >
> > Ideally the xmlpickle data should be addressable using
> > standard Python notations, e.g. a.b, a['b'] and a[0].
> >
> > Which of the two possibilities I posted would fit this model
> > w/r to Xpath ?
> 
> No matter how you do it, XPath won't look like python.  The "." is not
> valid in XPath.  Attributes are accessed as with the attribute:: axis
> (or @).  Ex.
> 
> <Employees Department="Development"/>
>   <Employee name="Mike">
>     <Adress>1234 S West Way</Address>
>   </Employee>
> </Employees>
> 
> To get Mike
> /Employees/Employee[@name="Mike"]
> To get Mikes Address with employee mike as the context:
> Address[0]

Hmm, looks like it would be more useful to map object names
to element names in this case... it doesn't really make sense
to access information on a type basis, e.g. 
/dictionary/item[@key="Mike"]. But then, structure is given by
type, not object name. Oh well :-/

BTW, how would one access "Mike" in this XML file without reverting to
positional indexing ?

<dictionary>
	<item>
		<key>Mike</key>
		<value><address>1234 Main Street</address></value>
	</item>
</dictionary>

It seems that these XPath lookups have to be context senstive...

-- 
Marc-Andre Lemburg
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