Data::Compare(3) User Contributed Perl Documentation Data::Compare(3)NAMEData::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 ALSOperl(1), perlref(1)perl v5.16.2 2010-02-11 Data::Compare(3)