#!/usr/bin/rexx
/*----------------------------------------------------------------------------*/
/* */
/* Copyright (c) 1995, 2004 IBM Corporation. All rights reserved. */
/* Copyright (c) 2005-2006 Rexx Language Association. All rights reserved. */
/* */
/* This program and the accompanying materials are made available under */
/* the terms of the Common Public License v1.0 which accompanies this */
/* distribution. A copy is also available at the following address: */
/* http://www.oorexx.org/license.html */
/* */
/* Redistribution and use in source and binary forms, with or */
/* without modification, are permitted provided that the following */
/* conditions are met: */
/* */
/* Redistributions of source code must retain the above copyright */
/* notice, this list of conditions and the following disclaimer. */
/* Redistributions in binary form must reproduce the above copyright */
/* notice, this list of conditions and the following disclaimer in */
/* the documentation and/or other materials provided with the distribution. */
/* */
/* Neither the name of Rexx Language Association nor the names */
/* of its contributors may be used to endorse or promote products */
/* derived from this software without specific prior written permission. */
/* */
/* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS */
/* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT */
/* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS */
/* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT */
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/* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, */
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/* */
/*----------------------------------------------------------------------------*/
/******************************************************************************/
/* greply.rex Open Object Rexx Samples */
/* */
/* Using the GUARD instruction to control methods */
/* */
/* */
/* -------------------------------------------------------------------------- */
/* */
/* Description: */
/* This program demonstrates the difference between Guarded and UnGuarded */
/* methods. In the first example, the method is guarded, so it does not */
/* begin execution until the final result is tallied. In the second */
/* example, the method is unguarded so it can begin execution while method */
/* sum_up is still looping. In fact, unguarded_get often runs immediately */
/* after the Reply, so we use a guard instruction to ensure sum_up runs for */
/* a bit before unguarded_get returns with the intermediate sum. */
/******************************************************************************/
/* guarded_get will wait until sum_up has completed */
Say 'Using GUARDED method to wait until sum is complete:'
Say 'Result should be 12502500:' .counter~new~~sum_up(5000)~guarded_get
Say ''
/* unguarded_get will begin execution before sum_up has completed */
Say 'Using UNGUARDED method to obtain an intermediate result:'
Say 'Result should be less than 12502500:' .counter~new~~sum_up(5000)~unguarded_get
Exit
::CLASS counter
::Method sum_up
Expose o_var
o_var = 0 /* Initialize our counter */
Reply o_var /* Early reply so others may run */
Do i = 1 to arg(1) /* Loop here for a bit */
o_var = o_var + i
/* Let them know we're still here */
If i//1000 = 0 Then Say 'Inside method sum_up: loop iteration' i
End
::Method guarded_get /* GUARD is default */
Expose o_var
Return o_var
::Method unguarded_get unguarded
Expose o_var
Guard off when o_var > 9999 /* Wait until count progresses a bit */
Return o_var /* Return intermediate result */
