Data::Compare(3pm)

1Data::Compare(3)      User Contributed Perl Documentation     Data::Compare(3)
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NAME

6       Data::Compare - compare perl data structures
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SYNOPSIS

9           use Data::Compare;
10
11           my $h1 = { 'foo' => [ 'bar', 'baz' ],  'FOO' => [ 'one', 'two' ] };
12           my $h2 = { 'foo' => [ 'bar', 'barf' ], 'FOO' => [ 'one', 'two' ] };
13           my @a1 = ('one', 'two');
14           my @a2 = ('bar', 'baz');
15           my %v = ( 'FOO', \@a1, 'foo', \@a2 );
16
17           # simple procedural interface
18           print 'structures of $h1 and \%v are ',
19             Compare($h1, \%v) ? "" : "not ", "identical.\n";
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21           print 'structures of $h1 and $h2 are ',
22             Compare($h1, $h2, { ignore_hash_keys => [qw(foo)] }) ? '' : 'not ',
23             "close enough to identical.\n";
24
25           # OO usage
26           my $c = new Data::Compare($h1, \%v);
27           print 'structures of $h1 and \%v are ',
28             $c->Cmp ? "" : "not ", "identical.\n";
29           # or
30           my $c = new Data::Compare;
31           print 'structures of $h and \%v are ',
32             $c->Cmp($h1, \%v) ? "" : "not ", "identical.\n";
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DESCRIPTION

35       Compare two perl data structures recursively. Returns 0 if the
36       structures differ, else returns 1.
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38       A few data types are treated as special cases:
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40       Scalar::Properties objects
41           This has been moved into a plugin, although functionality remains
42           the same as with the previous version.  Full documentation is in
43           Data::Compare::Plugins::Scalar::Properties.
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45       Compiled regular expressions, eg qr/foo/
46           These are stringified before comparison, so the following will
47           match:
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49               $r = qr/abc/i;
50               $s = qr/abc/i;
51               Compare($r, $s);
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53           and the following won't, despite them matching *exactly* the same
54           text:
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56               $r = qr/abc/i;
57               $s = qr/[aA][bB][cC]/;
58               Compare($r, $s);
59
60           Sorry, that's the best we can do.
61
62       CODE and GLOB references
63           These are assumed not to match unless the references are identical
64           - ie, both are references to the same thing.
65
66       You may also customise how we compare structures by supplying options
67       in a hashref as a third parameter to the "Compare()" function.  This is
68       not yet available through the OO-ish interface.  These options will be
69       in force for the *whole* of your comparison, so will apply to
70       structures that are lurking deep down in your data as well as at the
71       top level, so beware!
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73       ignore_hash_keys
74           an arrayref of strings. When comparing two hashes, any keys
75           mentioned in this list will be ignored.
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CIRCULAR STRUCTURES

78       Comparing a circular structure to itself returns true:
79
80           $x = \$y;
81           $y = \$x;
82           Compare([$x, $y], [$x, $y]);
83
84       And on a sort-of-related note, if you try to compare insanely deeply
85       nested structures, the module will spit a warning.  For this to affect
86       you, you need to go around a hundred levels deep though, and if you do
87       that you have bigger problems which I can't help you with ;-)
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PLUGINS

90       The module takes plug-ins so you can provide specialised routines for
91       comparing your own objects and data-types.  For details see
92       Data::Compare::Plugins.
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94       Plugins are *not* available when running in "taint" mode.  You may also
95       make it not load plugins by providing an empty list as the argument to
96       import() - ie, by doing this:
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98           use Data::Compare ();
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100       A couple of functions are provided to examine what goodies have been
101       made available through plugins:
102
103       plugins
104           Returns a structure (a hash ref) describing all the comparisons
105           made available through plugins.  This function is *not* exported,
106           so should be called as Data::Compare::plugins().  It takes no
107           parameters.
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109       plugins_printable
110           Returns formatted text
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EXPORTS

113       For historical reasons, the Compare() function is exported.  If you
114       don't want this, then pass an empty list to import() as explained under
115       PLUGINS.  If you want no export but do want plugins, then pass the
116       empty list, and then call the register_plugins class method:
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118           use Data::Compare ();
119           Data::Compare->register_plugins;
120
121       or you could call it as a function if that floats your boat.
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SOURCE CODE REPOSITORY

124       <git://github.com/DrHyde/perl-modules-Data-Compare.git>
125

BUGS

127       Plugin support is not quite finished (see the the Github issue #5
128       <http://github.com/DrHyde/perl-modules-Data-Compare/issues/5> for
129       details) but is usable. The missing bits are bells and whistles rather
130       than core functionality.
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132       Plugins are unavailable if you can't change to the current directory.
133       This might happen if you started your process as a priveleged user and
134       then dropped priveleges.  If this affects you, please supply a portable
135       patch with tests.
136
137       Bug reports should be made on Github or by email.
138

AUTHOR

140       Fabien Tassin <fta@sofaraway.org>
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142       Portions by David Cantrell <david@cantrell.org.uk>
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COPYRIGHT and LICENCE

145       Copyright (c) 1999-2001 Fabien Tassin. All rights reserved.  This
146       program is free software; you can redistribute it and/or modify it
147       under the same terms as Perl itself.
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149       Some parts copyright 2003 - 2014 David Cantrell.
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151       Seeing that Fabien seems to have disappeared, David Cantrell has become
152       a co-maintainer so he can apply needed patches.  The licence, of
153       course, remains the same.  As the "perl licence" is "Artistic or GPL,
154       your choice", you can find them as the files ARTISTIC.txt and GPL2.txt
155       in the distribution.
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