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

NAME

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

SYNOPSIS

	 # ===== 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 );

EXTENDED SYNOPSIS

	 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|
	 <perldata>
	  <arrayref>
	   <item key="0">
	    <hashref>
	       <item key="fname">Fred</item>
	       <item key="lname">Flintstone</item>
	       <item key="residence">Bedrock</item>
	    </hashref>
	   </item>
	   <item key="1">
	    <hashref>
	       <item key="fname">Barney</item>
	       <item key="lname">Rubble</item>
	       <item key="residence">Bedrock</item>
	    </hashref>
	   </item>
	  </arrayref>
	 </perldata>
	 |;

	 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 );

	 # ===== USE COMPRESSION
	 $dump->pl2xml( $perl, $file.".gz" );

	 # ===== INCLUDE AN IN-DOCUMENT DTD
	 $dump->dtd;
	 my $xml_with_dtd = $dump->pl2xml( $perl );

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

DESCRIPTION

       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 pack-
       aging; if the modules are installed on the system where the perl objects are reconstituted from xml, they will behave as expected. Intu-
       itively, 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 pars-
       ing 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 chal-
       lenges 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.

       FUNCTIONS AND METHODS

       * new() - XML::Dumper constructor.
	   Creates a lean, mean, XML dumping machine. It's also completely at your disposal.

       * dtd -
	   Generates a Document Type Dictionary for the 'perldata' data type. The default behaviour is to embed the DTD in the XML, thereby creat-
	   ing 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.

	   Usage:

	     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

       * 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

       * 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.

       * 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 identi-
	   cal. This method is exported by default.

       * 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.

EXPORTS

       By default, the following methods are exported:

	 xml2pl, pl2xml, xml_compare, xml_identity

BUGS AND DEPENDENCIES

       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 subrou-
       tines.  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

       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.

REVISIONS AND CREDITS

       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 sug-
       gested 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.

CURRENT MAINTAINER

       Mike Wong <mike_w3@pacbell.net>

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

ORIGINAL AUTHOR

       Jonathan Eisenzopf <eisen@pobox.com>

SEE ALSO

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

perl v5.8.8							    2006-04-18							       Dumper(3pm)