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.