1MARC::File::USMARC(3) User Contributed Perl DocumentationMARC::File::USMARC(3)
2
3
4

NAME

6       MARC::File::USMARC - USMARC-specific file handling
7

SYNOPSIS

9           use MARC::File::USMARC;
10
11           my $file = MARC::File::USMARC->in( $filename );
12
13           while ( my $marc = $file->next() ) {
14               # Do something
15           }
16           $file->close();
17           undef $file;
18

EXPORT

20       None.
21

METHODS

23       decode( $string [, \&filter_func ] )
24
25       Constructor for handling data from a USMARC file.  This function takes
26       care of all the tag directory parsing & mangling.
27
28       Any warnings or coercions can be checked in the "warnings()" function.
29
30       The $filter_func is an optional reference to a user-supplied function
31       that determines on a tag-by-tag basis if you want the tag passed to it
32       to be put into the MARC record.  The function is passed the tag number
33       and the raw tag data, and must return a boolean.  The return of a true
34       value tells MARC::File::USMARC::decode that the tag should get put into
35       the resulting MARC record.
36
37       For example, if you only want title and subject tags in your MARC
38       record, try this:
39
40           sub filter {
41               my ($tagno,$tagdata) = @_;
42
43               return ($tagno == 245) ⎪⎪ ($tagno >= 600 && $tagno <= 699);
44           }
45
46           my $marc = MARC::File::USMARC->decode( $string, \&filter );
47
48       Why would you want to do such a thing?  The big reason is that creating
49       fields is processor-intensive, and if your program is doing read-only
50       data analysis and needs to be as fast as possible, you can save time by
51       not creating fields that you'll be ignoring anyway.
52
53       Another possible use is if you're only interested in printing certain
54       tags from the record, then you can filter them when you read from disc
55       and not have to delete unwanted tags yourself.
56
57       update_leader()
58
59       If any changes get made to the MARC record, the first 5 bytes of the
60       leader (the length) will be invalid.  This function updates the leader
61       with the correct length of the record as it would be if written out to
62       a file.
63
64       _build_tag_directory()
65
66       Function for internal use only: Builds the tag directory that gets put
67       in front of the data in a MARC record.
68
69       Returns two array references, and two lengths: The tag directory, and
70       the data fields themselves, the length of all data (including the
71       Leader that we expect will be added), and the size of the Leader and
72       tag directory.
73
74       encode()
75
76       Returns a string of characters suitable for writing out to a USMARC
77       file, including the leader, directory and all the fields.
78

80       MARC::Record
81

TODO

83       Make some sort of autodispatch so that you don't have to explicitly
84       specify the MARC::File::X subclass, sort of like how DBI knows to use
85       DBD::Oracle or DBD::Mysql.
86
87       Create a toggle-able option to check inside the field data for end of
88       field characters.  Presumably it would be good to have it turned on all
89       the time, but it's nice to be able to opt out if you don't want to take
90       the performance hit.
91

LICENSE

93       This code may be distributed under the same terms as Perl itself.
94
95       Please note that these modules are not products of or supported by the
96       employers of the various contributors to the code.
97

AUTHOR

99       Andy Lester, "<andy@petdance.com>"
100
101
102
103perl v5.8.8                       2005-04-27             MARC::File::USMARC(3)
Impressum