file::counterfile(3pm) [debian man page]

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)

Check Out this Related Man Page

local(n)							    [incr Tcl]								  local(n)

__________________________________________________________________________________________________________________________________________________

NAME

       local - create an object local to a procedure

SYNOPSIS

       itcl::local className objName ?arg arg ...?
_________________________________________________________________

DESCRIPTION

       The local command creates an [incr Tcl] object that is local to the current call frame.	When the call frame goes away, the object is auto-
       matically deleted.  This command is useful for creating objects that are local to a procedure.

       As a side effect, this command creates a variable named "itcl-local-xxx", where xxx is the name of the object that is created.  This  vari-
       able detects when the call frame is destroyed and automatically deletes the associated object.

EXAMPLE

       In  the	following example, a simple "counter" object is used within the procedure "test".  The counter is created as a local object, so it
       is automatically deleted each time the procedure exits.	The puts statements included in the constructor/destructor show the object  coming
       and going as the procedure is called.
	      itcl::class counter {
		  private variable count 0
		  constructor {} {
		      puts "created: $this"
		  }
		  destructor {
		      puts "deleted: $this"
		  }

		  method bump {{by 1}} {
		      incr count $by
		  }
		  method get {} {
		      return $count
		  }
	      }

	      proc test {val} {
		  local counter x
		  for {set i 0} {$i < $val} {incr i} {
		      x bump
		  }
		  return [x get]
	      }

	      set result [test 5]
	      puts "test: $result"

	      set result [test 10]
	      puts "test: $result"

	      puts "objects: [itcl::find objects *]"

KEYWORDS

       class, object, procedure

itcl																	  local(n)

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file::counterfile(3pm) [debian man page]

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