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 struc‐
36       tures 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.
44
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.
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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 struc‐
70       tures that are lurking deep down in your data as well as at the top
71       level, so beware!
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73       ignore_hash_keys
74           an arrayref of strings. When comparing two hashes, any keys men‐
75           tioned in this list will be ignored.
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CIRCULAR STRUCTURES

78       Comparing a circular structure to itself returns true:
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80           $x = \$y;
81           $y = \$x;
82           Compare([$x, $y], [$x, $y]);
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84       But comparing two different circular structures returns false:
85
86           $x = \$y;
87           $y = \$x;
88           Compare([$x, $y], [$y, $x]); # <-- note different order
89
90       And on a sort-of-related note, if you try to compare insanely deeply
91       nested structures, the module will spit a warning.  For this to affect
92       you, you need to go around a hundred levels deep though, and if you do
93       that you have bigger problems which I can't help you with ;-)
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PLUGINS

96       The module takes plug-ins so you can provide specialised routines for
97       comparing your own objects and data-types.  For details see Data::Com‐
98       pare::Plugins.
99
100       Plugins are *not* available when running in "taint" mode.
101
102       A couple of functions are provided to examine what goodies have been
103       made available through plugins:
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105       plugins
106           Returns a structure (a hash ref) describing all the comparisons
107           made available through plugins.  This function is *not* exported,
108           so should be called as Data::Compare::plugins().  It takes no
109           parameters.
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111       plugins_printable
112           Returns formatted text
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BUGS

115       Plugin support is not quite finished (see the TODO file for details)
116       but is usable.  The missing bits are bells and whistles rather than
117       core functionality.
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119       Plugins are unavailable if you can't change to the current directory.
120       This might happen if you started your process as a priveleged user and
121       then dropped priveleges.  This is due to how we check for Taintedness.
122       If this affects you, please supply a portable patch.
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AUTHOR

125       Fabien Tassin        fta@sofaraway.org
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127       Copyright (c) 1999-2001 Fabien Tassin. All rights reserved.  This pro‐
128       gram is free software; you can redistribute it and/or modify it under
129       the same terms as Perl itself.
130
131       Seeing that Fabien seems to have disappeared, David Cantrell has become
132       a co-maintainer so he can apply needed patches.  The licence, of
133       course, remains the same, and all communications about this module
134       should be CCed to Fabien in case he ever returns and wants his baby
135       back.
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137       Portions, including plugins, copyright 2003-2007 David Cantrell
138       david@cantrell.org.uk
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