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Dumper(3)	      User Contributed Perl Documentation	     Dumper(3)

       XML::Dumper - Perl module for dumping Perl objects from/to XML

	 # ===== Using an object
	 use XML::Dumper;
	 $dump = new XML::Dumper;

	 $xml  = $dump->pl2xml(	$perl );
	 $perl = $dump->xml2pl(	$xml );
	 $dump->pl2xml(	$perl, "my_perl_data.xml.gz" );

	 # ===== Using function	calls
	 use XML::Dumper;

	 $xml  = pl2xml( $perl );
	 $perl = xml2pl( $xml );

	 use XML::Dumper;
	 my $dump = new	XML::Dumper;

	 my $perl  = '';
	 my $xml   = '';

	 # ===== Convert Perl code to XML
	 $perl = [
		       fname	   => 'Fred',
		       lname	   => 'Flintstone',
		       residence   => 'Bedrock'
		       fname	   => 'Barney',
		       lname	   => 'Rubble',
		       residence   => 'Bedrock'
	 $xml =	$dump->pl2xml( $perl );

	 # ===== Dump to a file
	 my $file = "dump.xml";
	 $dump->pl2xml(	$perl, $file );

	 # ===== Convert XML to	Perl code
	 $xml =	q|
	   <item key="0">
	       <item key="fname">Fred</item>
	       <item key="lname">Flintstone</item>
	       <item key="residence">Bedrock</item>
	   <item key="1">
	       <item key="fname">Barney</item>
	       <item key="lname">Rubble</item>
	       <item key="residence">Bedrock</item>

	 my $perl = $dump->xml2pl( $xml	);

	 # ===== Convert an XML	file to	Perl code
	 my $perl = $dump->xml2pl( $file );

	 # ===== And serialize Perl code to an XML file
	 $dump->pl2xml(	$perl, $file );

	 $dump->pl2xml(	$perl, $file.".gz" );

	 my $xml_with_dtd = $dump->pl2xml( $perl );

	 $dump->dtd( $file, $url );
	 my $xml_with_link_to_dtd = $dump->pl2xml( $perl );

       XML::Dumper dumps Perl data to XML format. XML::Dumper can also read
       XML data	that was previously dumped by the module and convert it	back
       to Perl.	You can	use the	module read the	XML from a file	and write the
       XML to a	file. Perl objects are blessed back to their original
       packaging; if the modules are installed on the system where the perl
       objects are reconstituted from xml, they	will behave as expected.
       Intuitively, if the perl	objects	are converted and reconstituted	in the
       same environment, all should be well. And it is.

       Additionally, because XML benefits so nicely from compression,
       XML::Dumper understands gzipped XML files. It does so with an optional
       dependency on Compress::Zlib. So, if you	dump a Perl variable with a
       file that has an	extension of '.xml.gz',	it will	store and compress the
       file in gzipped format.	Likewise, if you read a	file with the
       extension '.xml.gz', it will uncompress the file	in memory before
       parsing the XML back into a Perl	variable.

       Another fine challenge that this	module rises to	meet is	that it
       understands circular definitions	and multiple references	to a single
       object. This includes doubly-linked lists, circular references, and the
       so-called 'Flyweight' pattern of	Object Oriented	programming. So	it can
       take the	gnarliest of your perl data, and should	do just	fine.

       One caveat; XML::Dumper does not	handle binary data. There have been
       discussions in the expat	mailing	list archives discussing the
       challenges associated with encoding binary data with XML. I chose the
       cowardly	path of	making the problem a non-issue by not addressing it.
       To store	binary data, one could encode the data into ASCII before
       encapsulating the data as XML, and then reverse the process to restore
       the data. There are several Perl	modules	that one can use for this,
       Convert::UU, for	example.

       o   new() - XML::Dumper constructor.

	   Creates a lean, mean, XML dumping machine. It's also	completely at
	   your	disposal.

       o   dtd -

	   Generates a Document	Type Dictionary	for the	'perldata' data	type.
	   The default behaviour is to embed the DTD in	the XML, thereby
	   creating valid XML. Given a filename, the DTD will be written out
	   to that file	and the	XML document for your Perl data	will link to
	   the file. Given a filename and an URL, the DTD will be written out
	   the file and	the XML	document will link to the URL.	XML::Dumper
	   doesn't try really hard to determine	where your DTD's ought to go
	   or relative paths or	anything, so be	careful	with what arguments
	   you supply this method, or just go with the default with the
	   embedded DTD. Between DTD's and Schemas, the	potential for more
	   free-form data to be	imported and exported becomes feasible.


	     dtd();				   # Causes XML	to include embedded DTD
	     dtd( $file	);		   # DTD saved to $file; XML will link to $file
	     dtd( $file, $url );   # DTD saved to $file; XML will link to $url
	     dtd( 0 );				   # Prevents XML from including embedded DTD

       o   pl2xml( $xml, [ $file ] ) -

	   (Also perl2xml(), for those who enjoy readability over brevity).

	   Converts Perl data to XML. If a second argument is given, then the
	   Perl	data will be stored to disk as XML, using the second argument
	   as a	filename.

	   Usage: See Synopsis

       o   xml2pl( $xml_or_filename, [ $callback ] ) -

	   (Also xml2perl(), for those who enjoy readability over brevity.)

	   Converts XML	to a Perl datatype. If this method is given a second
	   argument, XML::Dumper will use the second argument as a callback
	   (if possible). If the first argument	isn't XML and exists as	a
	   file, that file will	be read	and its	contents will be used as the
	   input XML.

	   Currently, the only supported invocation of callbacks is through
	   soft	references. That is to say, the	callback argument ought	to be
	   a string that matches the name of a callable	method for your
	   classes. If you have	a congruent interface, this should work	like a
	   peach. If your class	interface doesn't have such a named method, it
	   won't be called.

       o   xml_compare(	$xml1, $xml2 ) - Compares xml for content

	   Compares two	dumped Perl data structures (that is, compares the
	   xml)	for identity in	content. Use this function rather than perl's
	   built-in string comparison. This function will return true for any
	   two perl data that are either deep clones of	each other, or
	   identical. This method is exported by default.

       o   xml_identity( $xml1,	$xml2 )	- Compares xml for identity

	   Compares two	dumped Perl data structures (that is, compares the
	   xml)	for identity in	instantiation. This function will return true
	   for any two perl data that are identical, but not for deep clones
	   of each other. This method is also exported by default.

       By default, the following methods are exported:

	 xml2pl, pl2xml, xml_compare, xml_identity

       XML::Dumper has changed API since 0.4, as a response to a bug report
       from PerlMonks. I felt it was necessary,	as the functions simply	didn't
       work as advertised. That	is, xml2pl really didnt	accept xml as an
       argument; what it wanted	was an XML Parse tree. To correct for the API
       change, simply don't parse the XML before feeding it to XML::Dumper.

       XML::Dumper also	has no understanding of	typeglobs (references or not),
       references to regular expressions, or references	to Perl	subroutines.
       Turns out that Data::Dumper doesn't do references to Perl subroutines,
       either, so at least I'm in somewhat good	company.

       XML::Dumper requires one	perl module, available from CPAN


       XML::Parser itself relies on Clark Cooper's Expat implementation	in
       Perl, which in turn requires James Clark's expat	package	itself.	See
       the documentation for XML::Parser for more information.

       The list	of credits got so long that I had to move it to	the Changes
       file. Thanks to all those who've	contributed with bug reports and
       suggested features! Keep	'em coming!

       I've had	ownership of the module	since June of 2002, and	very much
       appreciate requests on how to make the module better. It	has served me
       well, both as a learning	tool on	how I can repay	my debt	to the Perl
       Community, and as a practical module that is useful. I'm	thrilled to be
       able to offer this bit of code. So, if you have suggestions, bug
       reports,	or feature requests, please let	me know	and I'll do my best to
       make this a better module.

       Mike Wong <>

       XML::Dumper is free software. You can redistribute it and/or modify it
       under the same terms as Perl itself.

       Jonathan	Eisenzopf <>

       perl(1) Compress::Zlib(3) XML::Parser(3)	Data::DumpXML(3)

perl v5.32.0			  2006-04-05			     Dumper(3)


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