debian man page for hash::withdefaults

Hash::WithDefaults(3pm) 				User Contributed Perl Documentation				   Hash::WithDefaults(3pm)

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.

perl v5.14.2							    2012-05-26						   Hash::WithDefaults(3pm)