NAME
   File::CounterFile - Persistent counter class

SYNOPSIS
    use File::CounterFile;
    $c = new File::CounterFile "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 might try to access
   the same counters at the same time 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 is 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, that 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
   decrementd. 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 is 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 might use the `++'
   operator for incrementing the counter, `--' operator for
   decrementing and you can interpolate counters diretly into
   strings.

BUGS
   It uses flock(2) to lock the counter file. This does not work on
   all systems. Perhaps we should use the File::Lock module?

COPYRIGHT
   Copyright (c) 1995-1998 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 <[email protected]>