Re: msxml3 [1/4]: Add initial implementations of IXMLElement and IXMLElementCollection

[Huw Davies]

On Thu, May 17, 2007 at 04:40:06PM -0500, James Hawkins wrote:
> Changelog:
> - Add initial implementations of IXMLElement and IXMLElementCollection.

I can't help thinking that it would have been cleaner to implement the
IXML stuff using the IXMLDOM interfaces rather than straight on top of
libxml.  That way we only get one set of interfaces that depend on
libxml.  It may not be possible, but I think it would be worth a look.

Huw.

msxml3 [1/4]: Add initial implementations of IXMLElement and IXMLElementCollection

[James Hawkins]

On 5/18/07, Huw Davies  wrote:
> On Thu, May 17, 2007 at 04:40:06PM -0500, James Hawkins wrote:
> > Changelog:
> > - Add initial implementations of IXMLElement and IXMLElementCollection.
>
> I can't help thinking that it would have been cleaner to implement the
> IXML stuff using the IXMLDOM interfaces rather than straight on top of
> libxml.  That way we only get one set of interfaces that depend on
> libxml.  It may not be possible, but I think it would be worth a look.

I've taken a look, and I don't think it's possible.  Here is a 1-to-1
matching of methods in IXMLDocument and IXMLDOMDocument, respectively:

xmldoc_get_root                   => domdoc_documentElement
xmldoc_get_fileSize
xmldoc_put_fileModifiedDate
xmldoc_get_fileUpdatedDate
xmldoc_get_URL                  => domdoc_get_url
xmldoc_put_URL                  => domdoc_load
xmldoc_get_mimeType
xmldoc_get_readyState         => domdoc_get_readyState
xmldoc_get_charset
xmldoc_put_charset
xmldoc_get_version
xmldoc_get_doctype             => domdoc_get_doctype
xmldoc_get_dtdURl
xmldoc_createElement         => domdoc_createElement

The rows with empty second columns have no matching IXMLDOMDocument
method, and more precisely, can't be implemented without access to
xmlDoc/NodePtr.  The file* methods aren't as simple as that, but
either way, they don't involve libxml2.  Another problem is the
discrepancies between the interface implementations.  For example,
IXMLDocument::get_tagName returns the name of the tag in all
upper-case, while IXMLDOMDocument's equivalent method preserves the
case of the tag name.  The Media Player 9 requires this behavior.

I understand your concerns about limiting use of libxml2, but I think
that the limitation can only apply to the respective groups of
interfaces, e.g., XMLDocument and co. vs. XMLDOMDocument and co.  The
latest version of each interface implements the interface using
libxml2, and each earlier version is implemented on top of the latest
version.