106 lines
5.3 KiB
Rexx
Executable File
106 lines
5.3 KiB
Rexx
Executable File
#!@OOREXX_SHEBANG_PROGRAM@
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/*----------------------------------------------------------------------------*/
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/* */
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/* Copyright (c) 2005-2014 Rexx Language Association. All rights reserved. */
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/* */
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/* This program and the accompanying materials are made available under */
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/* the terms of the Common Public License v1.0 which accompanies this */
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/* distribution. A copy is also available at the following address: */
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/* https://www.oorexx.org/license.html */
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/* */
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/* Redistribution and use in source and binary forms, with or */
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/* without modification, are permitted provided that the following */
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/* conditions are met: */
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/* */
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/* Redistributions of source code must retain the above copyright */
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/* notice, this list of conditions and the following disclaimer. */
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/* Redistributions in binary form must reproduce the above copyright */
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/* notice, this list of conditions and the following disclaimer in */
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/* the documentation and/or other materials provided with the distribution. */
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/* */
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/* Neither the name of Rexx Language Association nor the names */
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/* of its contributors may be used to endorse or promote products */
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/* derived from this software without specific prior written permission. */
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/* */
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/* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS */
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/* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT */
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/* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS */
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/* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT */
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/* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, */
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/* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED */
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/* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, */
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/* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY */
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/* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING */
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/* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS */
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/* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
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/* */
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/*----------------------------------------------------------------------------*/
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/******************************************************************************/
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/* delegation.rex Open Object Rexx Samples */
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/* */
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/* -------------------------------------------------------------------------- */
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/* */
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/* Description: */
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/* Demonstrate the concept of a object method delegation, where one object */
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/* can pass on a method to another object */
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/******************************************************************************/
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delegator = .delegator~new -- no delegate
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say delegator~something
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-- an invalid delegate type
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delegator~delegate = "Some string"
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say delegator~something
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-- but we can try another method that the string does have
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say delegator~reverse
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-- an arbitrary object as a delegate
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delegator~delegate = .thing~new
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say delegator~heyThing
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-- a directory object with a thing entry defined
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d = .directory~new
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d~thing = "A thing in a directory"
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delegator~delegate = d
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say delegator~thing
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-- a class we can use as a delegate
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::class thing
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::method heyThing
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return "hey back at you!"
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-- A delegator object. The delegator will
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-- pass on all unknown methods to the delegate object
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::class delegator
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::method init
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expose delegate
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use strict arg delegate = .nil
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-- attribute method to allow the delegate to be changed
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::attribute delegate
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-- An UNKNOWN method to intercept unknown messages and pass them
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-- along to the delegate object
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::method unknown
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expose delegate
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use arg message, args
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if delegate == .nil then return "default implementation"
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-- Note: We could use delegate~hasMethod(message) to check
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-- for a THING method, but this will fail of the object relies
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-- on an UNKNOWN method to handle the method. By trapping
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-- NOMETHOD conditions, we can allow those calls to go
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-- through
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signal on nomethod
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-- use forward to dynamically invoke the target method.
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-- we specify CONTINUE so that our NOMETHOD handler can trap
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-- the error if the method does not exist
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forward to(delegate) message(message) arguments(args) continue
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-- return any returned result...if we actually got one.
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if var('RESULT') then return result
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return
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nomethod:
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return "default implementation"
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