# Tie::CPHash - phpMan

## NAME
    [Tie::CPHash] - Case preserving but case insensitive hash table

## VERSION
    This document describes version 2.000 of [Tie::CPHash], released January
    17, 2015.

## SYNOPSIS
        use [Tie::CPHash] 2; # allows initialization during tie
        tie %cphash, '[Tie::CPHash]', key => 'value';

        $cphash{'Hello World'} = 'Hi there!';
        printf("The key `%s' was used to store `%s'.\n",
               tied(%cphash)->key('HELLO WORLD'),
               $cphash{'HELLO world'});

## DESCRIPTION
    The [Tie::CPHash] module provides a hash table that is case preserving but
    case insensitive. This means that

        $cphash{KEY}    $cphash{key}
        $cphash{Key}    $cphash{keY}

    all refer to the same entry. Also, the hash remembers which form of the
    key was last used to store the entry. The "keys" and "each" functions
    will return the key that was used to set the value.

    An example should make this clear:

        tie %h, '[Tie::CPHash]', Hello => 'World';
        print $h{HELLO};            # Prints 'World'
        print keys(%h);             # Prints 'Hello'
        $h{HELLO} = 'WORLD';
        print $h{hello};            # Prints 'WORLD'
        print keys(%h);             # Prints 'HELLO'

    [Tie::CPHash] version 2.000 introduced the ability to pass a list of
    "key => value" pairs to initialize the hash (along with the "add" method
    that powers it). The list must include a value for each key, or the
    constructor will croak.

    The additional "key" method lets you fetch the case of a specific key:

        # When run after the previous example, this prints 'HELLO':
        print tied(%h)->key('Hello');

    (The "tied" function returns the object that %h is tied to.)

    If you need a case insensitive hash, but don't need to preserve case,
    just use $hash{lc $key} instead of $hash{$key}. This has a lot less
    overhead than [Tie::CPHash].

    "use [Tie::CPHash];" does not export anything into your namespace.

## METHODS
  add
      tied(%h)->add( key => value, ... );
      tied(%h)->add( \@list_of_key_value_pairs );

    This method (introduced in version 2.000) adds keys and values to the
    hash. It's just like

      %h = @list_of_key_value_pairs;

    except that it doesn't clear the hash first. It accepts either a list or
    an arrayref. It croaks if the list has an odd number of entries. It
    returns the tied hash object.

    If the list contains duplicate keys, the last "key => value" pair in the
    list wins. (You can't pass a hashref to "add" because it would be
    ambiguous which key would win if two keys differed only in case.)

    For people used to [Tie::IxHash], "add" is aliased to both "Push" and
    "Unshift". ([Tie::CPHash] does not preserve the order of keys.)

  key
      $set_using_key = tied(%h)->key( $key )

    This method lets you fetch the case of a specific key. For example:

      $h{HELLO} = 'World';
      print tied(%h)->key('Hello'); # prints HELLO

    If the key does not exist in the hash, it returns "undef".

## DIAGNOSTICS
    Odd number of elements in CPHash add
        You passed a list with an odd number of elements to the "add" method
        (or to "tie", which uses "add"). The list must contain a value for
        each key.

## CONFIGURATION AND ENVIRONMENT
    [Tie::CPHash] requires no configuration files or environment variables.

## INCOMPATIBILITIES
    None reported.

## BUGS AND LIMITATIONS
    No bugs have been reported.

## AUTHOR
    Christopher J. Madsen "<perl AT cjmweb.net>"

    Please report any bugs or feature requests to
    "<bug-Tie-CPHash AT rt.cpan.org>" or through the web interface at
    <<http://rt.cpan.org/Public/Bug/Report.html?Queue=Tie-CPHash>>.

    You can follow or contribute to Tie-CPHash's development at
    <<https://github.com/madsen/tie-cphash>>.

## COPYRIGHT AND LICENSE
    This software is copyright (c) 2015 by Christopher J. Madsen.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.

## DISCLAIMER OF WARRANTY
    BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
    FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
    OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
    PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER
    EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
    ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH
    YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
    NECESSARY SERVICING, REPAIR, OR CORRECTION.

    IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
    WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
    REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENSE, BE LIABLE
    TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR
    CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
    SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
    RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
    FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
    SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
    DAMAGES.