CounterFile(3pm)					User Contributed Perl Documentation					  CounterFile(3pm)

NAME

       File::CounterFile - Persistent counter class

SYNOPSIS

	use File::CounterFile;
	$c = File::CounterFile->new("COUNTER", "aa00");

	$id = $c->inc;
	open(F, ">F$id");

DESCRIPTION

       This module implements a persistent counter class.  Each counter is represented by a separate file in the file system.  File locking is
       applied, so multiple processes can attempt to access a counter simultaneously without risk of counter destruction.

       You give the file name as the first parameter to the object constructor ("new").  The file is created if it does not exist.

       If the file name does not start with "/" or ".", then it is interpreted as a file relative to $File::CounterFile::DEFAULT_DIR.  The default
       value for this variable is initialized from the environment variable "TMPDIR", or /usr/tmp if no environment variable is defined.  You may
       want to assign a different value to this variable before creating counters.

       If you pass a second parameter to the constructor, it sets the initial value for a new counter.	This parameter only takes effect when the
       file is created (i.e. it does not exist before the call).

       When you call the "inc()" method, you increment the counter value by one. When you call "dec()", the counter value is decremented.  In both
       cases the new value is returned.  The "dec()" method only works for numerical counters (digits only).

       You can peek at the value of the counter (without incrementing it) by using the "value()" method.

       The counter can be locked and unlocked with the "lock()" and "unlock()" methods.  Incrementing and value retrieval are faster when the
       counter is locked, because we do not have to update the counter file all the time.  You can query whether the counter is locked with the
       "locked()" method.

       There is also an operator overloading interface to the File::CounterFile object.  This means that you can use the "++" operator for
       incrementing and the "--" operator for decrementing the counter, and you can interpolate counters directly into strings.

COPYRIGHT

       Copyright (c) 1995-1998,2002,2003 Gisle Aas. All rights reserved.

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

AUTHOR

       Gisle Aas <gisle@aas.no>

perl v5.10.0							    2004-01-23							  CounterFile(3pm)