Josef Schönbrunner

NAME

Tie::Hash::Create - Extend Tie::ExtraHash, enables the tie-object to reflect the tied array

SYNOPSIS

    package Tie::Hash::MyClass; ## Choose your name for MyClass !
    use base Tie::Hash::Create;

    sub TIEHASH
    {
        my $class = shift;
        ..........................
        bless [{},undef,,,,],$class;
        # insert your stuff between the braces after "undef,"
    }

    # Optionally redefine other methods of Tie::Hash

------------ From within another file -----------

    use Tie::Hash::MyClass;

    my $myHash = Tie::Hash::MyClass->newHASH(....);

    # behaves as if

    my $myHash; tie %$myHash,'Tie::Hash::MyClass',...;

DESCRIPTION

Look at sections "Inheriting from Tie::ExtraHash" in Tie::Hash. Consider an object, say $tob returned by tie. It is an array, primitive hash-operations are carried out on the first field of this array, that is $tob->[0], a reference to a hash. Surprisingly this hash reference and the reference to the tied hash variable are not the same.

The purpose of this class is transmit to any derived class these features:

1. Store the reference to the real tied hash in the object $tob. 2. Define an accessor $tob->c to this hash. 3. Provide an operation newHASH which manages a tie but returns a reference to the real tied hash. This way the real hash-variable which appear as the first argument of tie is omitted. Instead newHASH returns an anonymous reference to this hash-object.

On the top of this file the package 'slot' defines a slot-name slot::HREF which identify an index positions of an object. A derived class could also define its own slot names. The choice of the index does not matter, however if two sources of code could not be reused in one class as each one stores data of different matters onto the same place, then it is easy to change one name-value assignment in package 'slot'. Of course the structure of an object created by the constructor must meet such a change, this applies for any derived class too.

OPERATORS

  • Constructor

    TIEHASH inherited from superclass Tie::ExtraHash. Note that the object returned by TIEHASH, the same as returned by tie is different from the reference to the tied hash.

    newHASH

    Calls the constructor TIEHASH, however returns the reference identifying the tied Hash.

    c (content operator)

    Assume $tob is an object of Tie::Hash::MyClass which is a subclass of Tie::Hash::Create and %H is the tied hash, so that $tob = tied %H. Then $tob->c evaluates to \%H.

SEE ALSO

A Sample class derived from Tie::Hash::Create is Tie::Hash::KeysMask.

PREREQUISITES

This module requires these other modules and libraries: Tie::Hash,<Tie::ExtraHash>

AUTHOR

Josef Schönbrunner <j.schoenbrunner@onemail.at>

COPYRIGHT AND LICENSE

Copyright (c) 2005 by Josef Schönbrunner This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.7 or, at your option, any later version of Perl 5 you may have available.