David Golden > File-Marker-0.13 > File::Marker

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Module Version: 0.13   Source   Latest Release: File-Marker-0.14

NAME ^

File::Marker - Set and jump between named position markers on a filehandle

VERSION ^

This documentation refers to version 0.13.

SYNOPSIS ^

 use File::Marker;

 my $fh = File::Marker->new( 'datafile.txt' );

 my $line1 = <$fh>;           # read a line
 $fh->set_marker( 'line2' );  # mark the current position
 my @rest = <$fh>;            # slurp the remainder
 $fh->goto_marker( 'line2' ); # jump back to the marked position
 my $line2 = <$fh>;           # read another line

DESCRIPTION ^

File::Marker allows users to set named markers for the current position in a filehandle and then later jump back to a marked position. A File::Marker object is a subclass of IO::File, providing full filehandle object functionality.

File::Marker automatically sets a special, reserved marker, 'LAST', when it jumps to a marker, allowing an easy return to a former position.

This module was written as a demonstration of the inside-out object technique for the NY Perl Seminar group. It is intended for teaching purposes and has not been tested in production code.

USAGE ^

new

 my $fh = new();
 my $fh = new( @args );

Creates and returns a File::Marker object. If arguments are provided, they are passed to open() before the object is returned. This mimics the behavior of IO::File.

open

 $fh->open( FILENAME [,MODE [,PERMS]] )
 $fh->open( FILENAME, IOLAYERS )

Opens a file for use with the File::Marker object. Arguments are passed directly to IO::File->open(). See IO::File for details. Returns true if successful and dies on failure.

set_marker

 $fh->set_marker( $marker_name );

Creates a named marker corresponding to the current position in the file. Dies if the filehandle is closed, if the position cannot be determined, or if the reserved marker name 'LAST' is used. Using the same name as an existing marker will overwrite the existing marker position.

goto_marker

 $fh->goto_marker( $marker_name );

Seeks to the position in the file corresponding to the given marker name. Dies if the filehandle is closed, if the marker name is unknown, or if the seek fails.

The reserved marker name 'LAST' corresponds to the location in the file prior to the most recent call to goto_marker on the object. For example:

 # starts at location X in the file
 $fh->goto_marker( 'one' );  # seek to location Y marked by 'one'
 $fh->goto_marker( 'LAST' ); # seek back to X
 $fh->goto_marker( 'LAST' ); # seek back to Y

If there have been no prior calls to goto_marker, 'LAST' will seek to the beginning of the file.

markers

 @list = $fh->markers();

Returns a list of markers that have been set on the object, including 'LAST'.

save_markers

 $fh->save_markers( $marker_filename );

Saves the current list of markers (excluding 'LAST') to the given filename.

load_markers

 $fh = File::Marker->new( 'datafile.txt' );
 $fh->load_markers( $marker_filename );

Loads markers from a previously-saved external file. Will overwrite any

LIMITATIONS ^

As with all inside-out objects, File::Marker is only thread-safe (including Win32 pseudo-forks) for Perl 5.8 or better, which supports the CLONE subroutine.

BUGS ^

Please report bugs or feature requests using the CPAN Request Tracker. Bugs can be sent by email to bug-File-Marker@rt.cpan.org or submitted using the web interface at http://rt.cpan.org/Public/Dist/Display.html?Name=File-Marker

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.

AUTHOR ^

David A. Golden (DAGOLDEN)

dagolden@cpan.org

http://dagolden.com/

COPYRIGHT AND LICENSE ^

Copyright (c) 2005, 2006 by David A. Golden

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

The full text of the license can be found in the LICENSE file included with this module.

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 LICENCE, 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.

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