Re: [xml-bindings]Python bindings suggestions

[Daniel Veillard <veillard redhat com>]

On Mon, Mar 04, 2002 at 07:01:18PM -0500, Daniel Veillard wrote:
> On Mon, Mar 04, 2002 at 10:05:03PM +0000, Gary Benson wrote:
> > This would probably be more easily done in the Python part:
> > 
> >     ret = _libxml.xmlNewTextChild(self._o, ns__o, name, content)
> >     if ret == None: raise error("xmlNewTextChild() failed")
> 
>   well I would have to define an treeError class and raise this, in this
> case. I agree this would simplify programming with the bindings a lot,
>   => TODO

  Done libxml2 wrapper can now raise treeError, parserError, uriError or
xpathError on functions or methods returning one of the libxml2 classes
and the return value being None.

> > My second suggestion is this: in quite a lot of Python modules where is
> > something that requires a callback there will be an example one filled
> > with empty functions. For the SAX parser, for example, something like 
> > (only a couple of methods shown):
> > 
> >     class SAXCallback:
[...]
> But I agree a full exemple should be provided at least.

  Done it describes all the SAX entry points, but doesn't show up
the xmllib compatibility callbacks which are accepted too.

> > 1. The only SAX parser creator seems to be a memory parser -- is there a 
> >    way of creating one that will parse a file instead? I'm currently 
> >    using something like:
> 
>   Hum, I would need a wrapper for something like
>     xmlDocPtr       xmlSAXParseFile         (xmlSAXHandlerPtr sax,
>                                              const char *filename,
> 					     int recovery);
> 
> >    It's not a problem, but it seems like something I should be able to do 
> >    with the library.
> 
>    agreed,

  Done:

def SAXParseFile(SAX, URI, recover):
    """Interface to parse an XML file or resource pointed by an
       URI to build an event flow to the SAX object"""
    libxml2mod.xmlSAXParseFile(SAX, URI, recover)

and

def htmlSAXParseFile(SAX, URI, encoding):
    """Interface to parse an HTML file or resource pointed by an
       URI to build an event flow to the SAX object"""
    libxml2mod.htmlSAXParseFile(SAX, URI, encoding)

  but untested.

> > 3. How do you evaluate an XPath expression with a relative path? For 
> >    instance, if the above example had worked and nodes[0] was an xmlNode, 
> >    how would I select into it? I'd _expect_ to do something like:
> > 
> >     film_node = nodes[0]
> >     photo = "12"
> >     ctxt2 = film_node.xpathNewContext()
> >     nodes2 = ctxt2.xpathEval(photo[ num=%s]" % photo)
> > 
> >    But of course that doesn't work ;-)
> 
>   The context should really be created against the document, but 
> an accessor should be added to allow setting the current node, this is
> lacking ATM, it's just an entry needed in libxml2-python-api.xml to 
> provided it.

  Done:
tests/xpath.py
-------------
ctxt = doc.xpathNewContext()
res = ctxt.xpathEval("//*")
...
ctxt.setContextNode(res[0])
res = ctxt.xpathEval("foo")
-------------

this has been commited in CVS:
 http://cvs.gnome.org/bonsai/cvsquery.cgi?module=gnome-xml&branch=HEAD&branchtype=match&dir=gnome-xml&file=&filetype=match&who=veillard&whotype=match&sortby=Date&hours=&date=explicit&mindate=03%2F05%2F02+10%3A40&maxdate=03%2F05%2F02+10%3A42&cvsroot=%2Fcvs%2Fgnome

 thanks for the feedback,

Daniel

-- 
Daniel Veillard      | Red Hat Network https://rhn.redhat.com/
veillard redhat com  | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
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