1WithDefaults(3)       User Contributed Perl Documentation      WithDefaults(3)
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SYNOPSIS

6         use Hash::WithDefaults;
7
8         %main = ( ... );
9         tie %h1, 'Hash::WithDefaults', {...};
10         tied(%h1)->AddDefault(\%main);
11         tie %h2, 'Hash::WithDefaults', {...};
12         tied(%h2)->AddDefault(\%main);
13
14         # now if you use $h1{$key}, the value is looked up first
15         # in %h1, then in %main.
16

DESCRIPTION

18       This module implements hashes that support "defaults". That is you may
19       specify several more hashes in which the data will be looked up in case
20       it is not found in the current hash.
21
22       Object creation
23
24               tie %hash, 'Hash::WithDefault', [$case_option], [\%values];
25               tie %hash, 'Hash::WithDefault', [$case_option], [%values];
26
27       The optional $case_option may be one of these values:
28
29         Sensitive     - the hash will be case sensitive
30         Tolower       - the hash will be case sensitive, all keys are made lowercase
31         Toupper       - the hash will be case sensitive, all keys are made uppercase
32         Preserve      - the hash will be case insensitive, the case is preserved
33         Lower - the hash will be case insensitive, all keys are made lowercase
34         Upper - the hash will be case insensitive, all keys are made uppercase
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36       If you pass a hash reference or an even list of keys and values to the
37       tie() function, those keys and values will be COPIED to the resulting
38       magical hash!
39
40       After you tie() the hash, you use it just like any other hash.
41
42       Functions
43
44       AddDefault
45
46               tied(%hash)->AddDefault(\%defaults);
47
48       This instructs the object to include the %defaults in the search for
49       values.  After this the value will be looked up first in %hash itself
50       and then in %defaults.
51
52       You may keep modifying the %defaults and your changes WILL be visible
53       through %hash!
54
55       You may add as many defaults to one Hash::WithDefaults object as you
56       like.
57
58       GetDefaults
59
60               $defaults = tied(%hash)->GetDefaults();
61               push @$defaults, \%another_default;
62
63       Returns a reference to the array that stores the defaults.  You may
64       delete or insert hash references into the array, but make sure you
65       NEVER EVER insert anything else than a hash reference into the array!
66
67       Config::IniHash example
68
69         use Config::IniHash;
70         $config = ReadIni $inifile, withdefaults => 1, insensitive => 'preserve';
71
72         if (exists $config->{':default'}) {
73           my $default = $config->{':default'};
74           foreach my $section (keys %$config) {
75             next if $section =~ /^:/;
76                 tied(%{$config->{$section}})->AddDefault($default)
77           }
78         }
79
80       And now all normal sections will get the default values from [:default]
81       section ;-)
82

AUTHOR

84       Jan Krynicky <Jenda@Krynicky.cz> http://Jenda.Krynicky.cz
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87       Copyright (c) 2002 Jan Krynicky <Jenda@Krynicky.cz>. All rights
88       reserved.
89
90       This program is free software; you can redistribute it and/or modify it
91       under the same terms as Perl itself.
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95perl v5.8.8                       2002-12-05                   WithDefaults(3)
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