=head1 NAME

Locale::Language - ISO two letter codes for language identification (ISO 639)

=head1 SYNOPSIS

    use Locale::Language;
    
    $lang = code2language('en');        # $lang gets 'English'
    $code = language2code('French');    # $code gets 'fr'
    
    @codes   = all_language_codes();
    @names   = all_language_names();


=head1 DESCRIPTION

The C<Locale::Language> module provides access to the ISO two-letter
codes for identifying languages, as defined in ISO 639. You can either
access the codes via the L<conversion routines> (described below),
or via the two functions which return lists of all language codes or
all language names.


=head1 CONVERSION ROUTINES

There are two conversion routines: C<code2language()> and C<language2code()>.

=over 4

=item code2language()

This function takes a two letter language code and returns a string
which contains the name of the language identified. If the code is
not a valid language code, as defined by ISO 639, then C<undef>
will be returned.

    $lang = code2language($code);

=item language2code()

This function takes a language name and returns the corresponding
two letter language code, if such exists.
If the argument could not be identified as a language name,
then C<undef> will be returned.

    $code = language2code('French');

The case of the language name is not important.
See the section L<KNOWN BUGS AND LIMITATIONS> below.

=back


=head1 QUERY ROUTINES

There are two function which can be used to obtain a list of all
language codes, or all language names:

=over 4

=item C<all_language_codes()>

Returns a list of all two-letter language codes.
The codes are guaranteed to be all lower-case,
and not in any particular order.

=item C<all_language_names()>

Returns a list of all language names for which there is a corresponding
two-letter language code. The names are capitalised, and not returned
in any particular order.

=back


=head1 EXAMPLES

The following example illustrates use of the C<code2language()> function.
The user is prompted for a language code, and then told the corresponding
language name:

    $| = 1;    # turn off buffering
    
    print "Enter language code: ";
    chop($code = <STDIN>);
    $lang = code2language($code);
    if (defined $lang)
    {
        print "$code = $lang\n";
    }
    else
    {
        print "'$code' is not a valid language code!\n";
    }

=head1 KNOWN BUGS AND LIMITATIONS

=over 4

=item *

In the current implementation, all data is read in when the
module is loaded, and then held in memory.
A lazy implementation would be more memory friendly.

=item *

Currently just supports the two letter language codes -
there are also three-letter codes, and numbers.
Would these be of any use to anyone?

=back

=head1 SEE ALSO

=over 4

=item Locale::Country

ISO codes for identification of country (ISO 3166).
Supports 2-letter, 3-letter, and numeric country codes.

=item Locale::Script

ISO codes for identification of written scripts (ISO 15924).

=item Locale::Currency

ISO three letter codes for identification of currencies and funds (ISO 4217).

=item ISO 639:1988 (E/F)

Code for the representation of names of languages.

=item http://lcweb.loc.gov/standards/iso639-2/langhome.html

Home page for ISO 639-2.

=back


=head1 AUTHOR

Neil Bowers E<lt>neil@bowers.comE<gt>

=head1 COPYRIGHT

Copyright (C) 2002, Neil Bowers.

Copyright (c) 1997-2001 Canon Research Centre Europe (CRE).

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

=cut