Re: Questions about XML:LibXML

fergus@xxxxxxxxxxxxxxxx (Fergus McMenemie) wrote:
I am currently migrating several large scripts from XML::DOM to
XML::LIBXML and the transistion has hightligted a number of problems.

Out of my own curiosity, what is the driving force behind the change?

Both modules have rather poorly documented aspects and the move to
XML::LIBXML is proving painful.

A typical use of either module to read XML goes along the lines of

my $parser =XML::LibXML->new();
my $tree = $parser->parse_file($metafile);

XML::LIBXML seems to require an extra step of

my $pubmeta = $tree->getDocumentElement();

I think my misunderstandings starts at the very first line.
- What this $parser object do?

It lets you set the default options to the parser. If you never do
that (and the docs don't even explain how you would go about doing it)
then it is pretty useless. Consider just another part of the bloat and rot
that seems to follow XML where ever it goes.

If I am parsing multiple files
do I need a seperate parser instance for each file?

No. But I would use one anyway. Creation of a XML::LibXML parser
is extremely light weight (unlike XML::DOM).

- Having used parse_file() within a subroutine do I need to
keep it around or is it just $tree that needs kept?

- Or can I get away with just keeping $pubmeta in scope?

You can do even better, not even explicitly having the intermediaries:

my $pubmeta =
XML::LibXML->new()->parse_file($metafile)->getDocumentElement();


In answering or commenting on the above bear in mind that I am
opening lots of XML files, merging elements from them into a master.

Using the same parser over and over in XML::LibXML might save you around
one second for every few hundred thousand files or so. Not worth worrying
about in my book.

Xho

--
-------------------- http://NewsReader.Com/ --------------------
The costs of publication of this article were defrayed in part by the
payment of page charges. This article must therefore be hereby marked
advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate
this fact.
.

Relevant Pages

  • Re: Word 2003 XML
    ... In essence the parser determines whether the XML provided to it, ... have much info. about the schemas associated with an XML document. ... (which is what namespaces are all about). ...
    (microsoft.public.mac.office.word)
  • Re: My Regexp XML Parser -> Structured Perl Data, Cut & Paste Version, No Modules (Vol I)
    ... >>>but that's totally useless for XML parsing. ... >Your parser has no appreciation of nesting beyond the very trivial, ... >going to be for your parser to validate against one. ... Wheather or not I can use it to write a schema checker is something I ...
    (comp.lang.perl.misc)
  • Re: SAX PARSING DESIGN PATTERN
    ... I am parsing out an xml document using a sax parser. ... In the class that implements the parser element for a given tag I include a reference to the parent parser element object. ... The parsing loop will retrieve a handler for the current tag during startElement() and set its "parent" instance variable to the current AbstractHandler before pointing currentHandler at the new one. ... Or does your SAX parser actually have StartElementand EndElementmethods? ...
    (comp.lang.java.programmer)
  • [ANN] XSD/e 1.1.0 - validating XML parser generator for embedded systems
    ... I am pleased to announce the availability of CodeSynthesis XSD/e 1.1.0. ... CodeSynthesis XSD/e is an open-source XML ... parser generator for mobile and embedded systems. ...
    (comp.arch.embedded)
  • [ANN] XSD/e 1.1.0 - validating XML parser generator for embedded systems
    ... I am pleased to announce the availability of CodeSynthesis XSD/e 1.1.0. ... CodeSynthesis XSD/e is an open-source XML ... parser generator for mobile and embedded systems. ...
    (microsoft.public.windowsce.embedded.vc)