Hash::WithDefaults(3pmUser Contributed Perl DocumentatiHash::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 v5.34.0 2022-10-13 Hash::WithDefaults(3pm)
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