MARC::File::USMARC - phpMan

NAME
    MARC::File::USMARC - USMARC-specific file handling

SYNOPSIS
        use MARC::File::USMARC;

        my $file = MARC::File::USMARC->in( $filename );

        while ( my $marc = $file->next() ) {
            # Do something
        }
        $file->close();
        undef $file;

EXPORT
    None.

METHODS
  decode( $string [, \&filter_func ] )
    Constructor for handling data from a USMARC file. This function takes
    care of all the tag directory parsing & mangling.

    Any warnings or coercions can be checked in the "warnings()" function.

    The $filter_func is an optional reference to a user-supplied function
    that determines on a tag-by-tag basis if you want the tag passed to it
    to be put into the MARC record. The function is passed the tag number
    and the raw tag data, and must return a boolean. The return of a true
    value tells MARC::File::USMARC::decode that the tag should get put into
    the resulting MARC record.

    For example, if you only want title and subject tags in your MARC
    record, try this:

        sub filter {
            my ($tagno,$tagdata) = @_;

            return ($tagno == 245) || ($tagno >= 600 && $tagno <= 699);
        }

        my $marc = MARC::File::USMARC->decode( $string, \&filter );

    Why would you want to do such a thing? The big reason is that creating
    fields is processor-intensive, and if your program is doing read-only
    data analysis and needs to be as fast as possible, you can save time by
    not creating fields that you'll be ignoring anyway.

    Another possible use is if you're only interested in printing certain
    tags from the record, then you can filter them when you read from disc
    and not have to delete unwanted tags yourself.

  update_leader()
    If any changes get made to the MARC record, the first 5 bytes of the
    leader (the length) will be invalid. This function updates the leader
    with the correct length of the record as it would be if written out to a
    file.

  _build_tag_directory()
    Function for internal use only: Builds the tag directory that gets put
    in front of the data in a MARC record.

    Returns two array references, and two lengths: The tag directory, and
    the data fields themselves, the length of all data (including the Leader
    that we expect will be added), and the size of the Leader and tag
    directory.

  encode()
    Returns a string of characters suitable for writing out to a USMARC
    file, including the leader, directory and all the fields.

RELATED MODULES
    MARC::Record

TODO
    Make some sort of autodispatch so that you don't have to explicitly
    specify the MARC::File::X subclass, sort of like how DBI knows to use
    DBD::Oracle or DBD::Mysql.

    Create a toggle-able option to check inside the field data for end of
    field characters. Presumably it would be good to have it turned on all
    the time, but it's nice to be able to opt out if you don't want to take
    the performance hit.

LICENSE
    This code may be distributed under the same terms as Perl itself.

    Please note that these modules are not products of or supported by the
    employers of the various contributors to the code.

AUTHOR
    Andy Lester, "<andy AT petdance.com>"