Data::Compare(3)					User Contributed Perl Documentation					  Data::Compare(3)

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.
";

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

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

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)

perl v5.16.2							    2010-02-11							  Data::Compare(3)