Re: libxml2 application data

Dne Monday 22 December 2008 14:48:20 philippe marguinaud napsal(a):
> Hi Petr,
>
> I have thought about using the $$node trick, but when the XML tree is
> modified ( for instance when a node is deleted ), then some of the nodes
> are re-numbered.

No, I doubt they get re-numbered as you put it. A scenario that I can think of 
is that you remove a node from the DOM and create a new one. In such a case 
of course the new node can take the memory address left by the old one, 
provided the old node was destroyed, and thus the new node's $$node would be 
equal to the old one. You have to take care of such cases in your code (e.g. 
before you make a DOM operation that destroys a node, you should remove the 
associated data from your hash).

> I can provide a demo script to illustrate this if you
> want. 

please do if you can think of some other case.

> So I am stuck with XML::LibXML, I will have to find another module.
>
> Regards,
> Philippe

I'm sorry. XML::LibXML does not currently provide the feature you ask for. I 
suggested a possible work-around. Other module may better suit your needs, I 
don't know them. But if you decide to implement user data over XML::LibXML, 
here are a few further suggestions:

You may wrap the critical DOM functions to deal with user-data transparently. 
If you do this meticulously, you can either replace XML::LibXML's DOM calls 
or create a new DOM layer on top of XML::LibXML. This all can be done in your 
application without modifying XML::LibXML itself.

You may also experiment with XML::LibXML's source code and find an way to 
implement user data inside XML::LibXML (either using _private or otherwise). 
I usually take patches for new features that make sense and that include 
self-tests and documentation. Any effort is welcome.

-- Petr

> > From: [email protected]
> > To: [email protected]
> > Subject: Re: libxml2 application data
> > Date: Mon, 22 Dec 2008 12:14:20 +0100
> > CC: [email protected]
> >
> > No, XML::LibXML uses the _private slot for its own purposes. I'd
> > suggest using a Perl hash and $$node as key ($$node is an integer
> > that uniquely identifies a libxml2's node).
> >
> > -- Petr
> >
> > On ne 21. prosince 2008, philippe marguinaud wrote:
> > > Hi all,
> > >
> > > I have written C programs using libxml2 and used to attach
> > > application data to xml nodes using the _private field of node
> > > structs. I would like to know whether it is possible to do that
> > > using the Perl bindings; I have not seen anything like that in
> > > the pod documentation.
> > >
> > > Regards,
> > >
> > > Philippe
> > >
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