[xml-bindings]Let's start

[Daniel Veillard <veillard redhat com>]

  Okay, seems the people who expressed interest in this list joined,
so let's start working on the open issues. Here are a few points:

   - tools: since the API is frozing, I can now express a reliable
     API description, I have put it (them there is one for libxslt)
     in the doc subdir as an XML file, it includes all exported entry
     points and API symbols and the associated comments, this should
     help generating reliable and complete bindings. One thing missing
     currently is the ENUMs values.

   - the error API, currently registered functions are expected
     to handle varargs starting with a format string. The libxml
     module actually preformats the string passed to the handler
     but passes it as handler(data, "%s", formatted_string)
     Calling directly handler(data, formatted_string) is not possible
     in the current state of the API because it opens the door wide
     to malicious attacks if the error context contains for example
     "%s". One way is to change error callbacks to simple
     strings, but it's an API breakage or we add a function to
     toggle the expected behaviour, the second is an API addition
     and sounds quite better.

   - classes and naming issues. Most of the binding languages provide
     the abstraction of classes. In those it would be good to have
     similar class names and hierarchy, and also do the remapping
     of names and attributes in a similar way. For examples in the
     current python bindings I have the following hierarchy:
       xmlCore
           xmlNode
	       xmlDoc
	       xmlEntity
	       xmlNs
	       xmlAttr
	       xmlAttribute
	       xmlDtd
	       xmlElement
       parserCtxt
       xpathContext
	       
     I have tried to remove some of the defficiencies of the C type system
     using xmlCore to provide an unified navigation definition and
     xmlNode for most tree APIs, then specific classes for really specific
     operations.
     This is completely exposed in python/libxml2class.txt
         
  there is probably a number of points I did not try try to fix, and also 
I tried to avoid mapping some types to non-natives ones, like for example
the xmlXPathObjects shows up as native python types.
  I don't know how realistic it is to really try to unify bindings, but
I'm open to suggestions, and I think there is a lot of work which can be
shared, at least between sub-groups of bindings.

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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