Re: [xml] XPath functions ignoring their name

[Daniel Veillard <veillard redhat com>]

On Tue, May 22, 2001 at 04:17:19AM +0200, Thomas Broyer wrote:
> Le 16/05/01 09:07:12, Daniel Veillard a écrit :
> > > As I explained in the xslt list, I need a way of retrieving the name
> > > of the currently called XPath function since I have a single function
> > > answering calls for multiple XPath functions (this is for the EXSLT -
> > > Functions implementation).
> >
> >   Hum, right, I see what you mean, something like self() in OO languages.
>
> Not exactly. If I use, e.g., the EXSLT set:distinct() function, the
> callback should be able to retrieve the local-name ("distinct') and
> namespace URI ("http://exslt.org/sets";) of the function.
> Have a look to the example of func:function in the libxslt list to see why
> I need this.

  I'm pretty sure this can be found in the current OP evaluated in the 
XPath module. Providing those is relatively simple.

> This is similar to the fact that, in libxslt, an element callback can
> access the local-name and namespace URI of the element (like in
> xsltDocumentElem)
>
> > > Can I add a pointer to the current xmlXPathSetOp, or its index in the
> > > comp->steps list, or directly to the function name and namespace URI
> > > (which of the three should I prefer?), in the xmlXPathParserContext?
> >
> >   If this is just needed at compilation time, I would prefer to have
> > it added at the end of xmlXPathParserContext.
>
> I wonder if it wouldn't be better passing them (local name and namespace
> URI) as const xmlChar* arguments to the callback function (modifying the
> xmlXPathEvalFunc type into «typedef void (*xmlXPathEvalFunc)
> (xmlXPathParserContextPtr ctxt, int nargs, const xmlChar *localName, const
> xmlChar *nsURI)»).
> This shouldn't break compatibility I guess.

  Hum this is very clear it does break compatibility. For example the
code in libxslt would need to be modified and the shared lib would
not work with a previous libxml shared lib. API and ABI breakage (of libxml).
Sorry, this is not possible. Extending the context is certainly cleaner
at this point.

Daniel

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