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

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
       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.
   FUNCTIONS AND METHODS
       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.
           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
       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.
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 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
       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
       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.
CURRENT MAINTAINER
       Mike Wong <mike_w3 AT 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 AT pobox.com>
SEE ALSO
       perl(1) Compress::Zlib(3) XML::Parser(3) Data::DumpXML(3)

perl v5.16.3                      2006-04-05                         Dumper(3)