??ANSWER TO EXERCISE 3

Briefly: provide a GamePreRoutine which tests to see if second is an object, rather than nothing or a number. If it is, check whether the object has a second_before rule (i.e. test the condition (object provides second_before)). If it has, send the second_before message to it, and return the reply as the return value from GamePreRoutine.


Back to the exercise in section 9
Mechanically translated to HTML from third edition as revised 16 May 1997. Copyright © Graham Nelson 1993, 1994, 1995, 1996, 1997: all rights reserved.