oracular (3) Hash::WithDefaults.3pm.gz

NAME

       Hash::WithDefaults - class for hashes with key-casing requirements supporting defaults

       version 0.05

SYNOPSIS

         use Hash::WithDefaults;

         %main = ( ... );
         tie %h1, 'Hash::WithDefaults', {...};
         tied(%h1)->AddDefault(\%main);
         tie %h2, 'Hash::WithDefaults', [...];
         tied(%h2)->AddDefault(\%main);

         # now if you use $h1{$key}, the value is looked up first
         # in %h1, then in %main.

DESCRIPTION

       This module implements hashes that support "defaults". That is you may specify several more hashes in
       which the data will be looked up in case it is not found in the current hash.

   Object creation
               tie %hash, 'Hash::WithDefault', [$case_option], [\%values];
               tie %hash, 'Hash::WithDefault', [$case_option], [\@values];
               tie %hash, 'Hash::WithDefault', [$case_option], [%values];

       The optional $case_option may be one of these values:

         Sensitive     - the hash will be case sensitive
         Tolower       - the hash will be case sensitive, all keys are made lowercase
         Toupper       - the hash will be case sensitive, all keys are made uppercase
         Preserve      - the hash will be case insensitive, the case is preserved
         Lower - the hash will be case insensitive, all keys are made lowercase
         Upper - the hash will be case insensitive, all keys are made uppercase

       If you pass a hash or array reference or an even list of keys and values to the tie() function, those
       keys and values will be COPIED to the resulting magical hash!

       After you tie() the hash, you use it just like any other hash.

   Functions
       AddDefault

               tied(%hash)->AddDefault(\%defaults);

       This instructs the object to include the %defaults in the search for values.  After this the value will
       be looked up first in %hash itself and then in %defaults.

       You may keep modifying the %defaults and your changes WILL be visible through %hash!

       You may add as many defaults to one Hash::WithDefaults object as you like, they will be searched in the
       order you add them.

       If you delete a key from the tied hash, it's only deleted from the list of specific keys, the defaults
       are never modified through the tied hash. This means that you may get a default value for a key after you
       deletethe key from the tied hash!

       GetDefaults

               $defaults = tied(%hash)->GetDefaults();
               push @$defaults, \%another_default;

       Returns a reference to the array that stores the defaults.  You may delete or insert hash references into
       the array, but make sure you NEVER EVER insert anything else than a hash reference into the array!

   Config::IniHash example
         use Config::IniHash;
         $config = ReadIni $inifile, withdefaults => 1, case => 'preserve';

         if (exists $config->{':default'}) {
           my $default = $config->{':default'};
           foreach my $section (keys %$config) {
             next if $section =~ /^:/;
                 tied(%{$config->{$section}})->AddDefault($default)
           }
         }

       And now all normal sections will get the default values from [:default] section ;-)

AUTHOR

       Jan Krynicky <Jenda@Krynicky.cz> http://Jenda.Krynicky.cz

COPYRIGHT

       Copyright (c) 2002-2009 Jan Krynicky <Jenda@Krynicky.cz>. All rights reserved.

       This program is free software; you can redistribute it and/or modify it under the same terms as Perl
       itself.