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)