NAME

       Data::Compare - compare perl data structures

SYNOPSIS

           use Data::Compare;

           my $h1 = { 'foo' => [ 'bar', 'baz' ],  'FOO' => [ 'one', 'two' ] };
           my $h2 = { 'foo' => [ 'bar', 'barf' ], 'FOO' => [ 'one', 'two' ] };
           my @a1 = ('one', 'two');
           my @a2 = ('bar', 'baz');
           my %v = ( 'FOO', \@a1, 'foo', \@a2 );

           # simple procedural interface
           print 'structures of $h1 and \%v are ',
             Compare($h1, \%v) ? "" : "not ", "identical.\n";

           print 'structures of $h1 and $h2 are ',
             Compare($h1, $h2, { ignore_hash_keys => [qw(foo)] }) ? '' : 'not ',
             "close enough to identical.\n";

           # OO usage
           my $c = new Data::Compare($h1, \%v);
           print 'structures of $h1 and \%v are ',
             $c->Cmp ? "" : "not ", "identical.\n";
           # or
           my $c = new Data::Compare;
           print 'structures of $h and \%v are ',
             $c->Cmp($h1, \%v) ? "" : "not ", "identical.\n";

DESCRIPTION

       Compare two perl data structures recursively. Returns 0 if the structures differ, else
       returns 1.

       A few data types are treated as special cases:

       Scalar::Properties objects
           This has been moved into a plugin, although functionality remains the same as with the
           previous version.  Full documentation is in
           Data::Compare::Plugins::Scalar::Properties.

       Compiled regular expressions, eg qr/foo/
           These are stringified before comparison, so the following will match:

               $r = qr/abc/i;
               $s = qr/abc/i;
               Compare($r, $s);

           and the following won't, despite them matching *exactly* the same text:

               $r = qr/abc/i;
               $s = qr/[aA][bB][cC]/;
               Compare($r, $s);

           Sorry, that's the best we can do.

       CODE and GLOB references
           These are assumed not to match unless the references are identical - ie, both are
           references to the same thing.

       You may also customise how we compare structures by supplying options in a hashref as a
       third parameter to the "Compare()" function.  This is not yet available through the OO-ish
       interface.  These options will be in force for the *whole* of your comparison, so will
       apply to structures that are lurking deep down in your data as well as at the top level,
       so beware!

       ignore_hash_keys
           an arrayref of strings. When comparing two hashes, any keys mentioned in this list
           will be ignored.

CIRCULAR STRUCTURES

       Comparing a circular structure to itself returns true:

           $x = \$y;
           $y = \$x;
           Compare([$x, $y], [$x, $y]);

       And on a sort-of-related note, if you try to compare insanely deeply nested structures,
       the module will spit a warning.  For this to affect you, you need to go around a hundred
       levels deep though, and if you do that you have bigger problems which I can't help you
       with ;-)

PLUGINS

       The module takes plug-ins so you can provide specialised routines for comparing your own
       objects and data-types.  For details see Data::Compare::Plugins.

       Plugins are *not* available when running in "taint" mode.  You may also make it not load
       plugins by providing an empty list as the argument to import() - ie, by doing this:

           use Data::Compare ();

       A couple of functions are provided to examine what goodies have been made available
       through plugins:

       plugins
           Returns a structure (a hash ref) describing all the comparisons made available through
           plugins.  This function is *not* exported, so should be called as
           Data::Compare::plugins().  It takes no parameters.

       plugins_printable
           Returns formatted text

EXPORTS

       For historical reasons, the Compare() function is exported.  If you don't want this, then
       pass an empty list to import() as explained under PLUGINS.  If you want no export but do
       want plugins, then pass the empty list, and then call the register_plugins class method:

           use Data::Compare ();
           Data::Compare->register_plugins;

       or you could call it as a function if that floats your boat.

CODE REPOSITORY

       <http://www.cantrell.org.uk/cgit/cgit.cgi/perlmodules/>

BUGS

       Plugin support is not quite finished (see the TODO file for details) but is usable.  The
       missing bits are bells and whistles rather than core functionality.

       Plugins are unavailable if you can't change to the current directory.  This might happen
       if you started your process as a priveleged user and then dropped priveleges.  This is due
       to how we check for Taintedness.  If this affects you, please supply a portable patch.

       Please report any other bugs either by email to David Cantrell (see below for address) or
       using rt.cpan.org:

       https://rt.cpan.org/Ticket/Create.html?Queue=Data-Compare
       <https://rt.cpan.org/Ticket/Create.html?Queue=Data-Compare>

AUTHOR

       Fabien Tassin <fta@sofaraway.org>

       Portions by David Cantrell <david@cantrell.org.uk>

COPYRIGHT and LICENCE

       Copyright (c) 1999-2001 Fabien Tassin. All rights reserved.  This program is free
       software; you can redistribute it and/or modify it under the same terms as Perl itself.

       Some parts copyright 2003 - 2010 David Cantrell.

       Seeing that Fabien seems to have disappeared, David Cantrell has become a co-maintainer so
       he can apply needed patches.  The licence, of course, remains the same.  As the "perl
       licence" is "Artistic or GPL, your choice", you can find them as the files ARTISTIC.txt
       and GPL2.txt in the distribution.

SEE ALSO

       perl(1), perlref(1)