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.
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@petdance.com>"