/ 
FileHandle-Rollback-1.00
/ FileHandle::Rollback

NAME

FileHandle::Rollback - FileHandle with commit and rollback

SYNOPSIS

use FileHandle::Rollback;
my ($fh);

# open file handle
$fh = FileHandle::Rollback->new("+< $path")
  or die "cannot open filehandle: $!";

# put some data at a specific address
$fh->seek(80, 0);
print $fh '1500';

# read some data, partially including data 
# that was written in this rollback segment
$fh->seek(70, 0);
$fh->read($data, 100);

# if you want to cancel the changes:
$fh->rollback;

# or, if you want save the changes:
$fh->commit;

DESCRIPTION

FileHandle::Rollback allows you to open a filehandle, write data to that handle, read the data back exactly as if it were already in the file, then cancel the whole transaction if you choose. FileHandle::Rollback works like FileHandle, with a few important differences, most notably the addition of rollback() and commit(). Those additions and differences are noted below.

$fh->rollback()

Cancels all changes since the last rollback, commit, or since you opened the file handle.

$fh->commit()

Writes changes to the file.

$fh->commit(flock, $mode)

The flock method locks the file like the built-in flock command. Use the same mode arguments: LOCK_SH, LOCK_EX, and LOCK_UN.

use Fcntl ':flock';

unless ($fh->flock(LOCK_EX))
  {die "cannot lock filehandle: $!"}

binmode

FileHandle::Rollback only works in binmode, so it will automatically put itself into binmode.

read/write

FileHandle::Rollback only works in read/write mode. Regardless of what you begin the file path with (+<, +>, >, >>, etc) FileHandle::Rollback opens the file with +< . However, if > is anywhere in the path then FileHandle::Rollback will create the file if it doesn't already exist.

TERMS AND CONDITIONS

Copyright (C) 2002 Miko O'Sullivan

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

AUTHOR

Miko O'Sullivan miko@idocs.com

VERSION

Version 1.00    June 29, 2002