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  • Committer: Bazaar Package Importer
  • Author(s): Mark Baker
  • Date: 2004-03-29 23:52:44 UTC
  • Revision ID: james.westby@ubuntu.com-20040329235244-fox1z1yv7d6vojoo
Tags: upstream-6.30
Import upstream version 6.30

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html/answers1/answer25.html
 
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<HTML><HEAD><TITLE>Answer to Exercise 25</TITLE></HEAD>
 
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<BODY BGCOLOR="#FFFFFF">
 
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<TABLE><TR><TD Valign="top"><IMG SRC="../icons/exercise.gif" ALT="??"><TD bgcolor="#FAA89B"><B>ANSWER TO EXERCISE 25</B><TR><TD><TD>
 
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<P>
 
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<PRE>
 
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[ PrintTime x; print (x/60), ":", (x%60)/10, (x%60)%10; ];
 
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Object -&#62; alarm_clock "alarm clock"
 
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  with name "alarm" "clock",
 
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       number 480,
 
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       description
 
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       [;  print "The alarm is ";
 
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           if (self has general) print "on, "; else print "off, but ";
 
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           "the clock reads ", (PrintTime) the_time,
 
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           " and the alarm is set for ", (PrintTime) self.number, ".";
 
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       ],
 
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       react_after
 
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       [;  Inv:  if (self in player)   { new_line; &#60;&#60;Examine self&#62;&#62;; }
 
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           Look: if (self in location) { new_line; &#60;&#60;Examine self&#62;&#62;; }
 
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       ],
 
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       daemon
 
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       [;  if (the_time &#62;= self.number &#38;&#38; the_time &#60;= self.number+3
 
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               &#38;&#38; self has general) "^Beep! Beep! The alarm goes off.";
 
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       ],
 
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       grammar [; return 'alarm,'; ],
 
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       orders
 
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       [;  SwitchOn:  give self general; StartDaemon(self); "~Alarm set.~";
 
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           SwitchOff: give self ~general; StopDaemon(self); "~Alarm off.~";
 
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           SetTo:     self.number=noun; &#60;&#60;Examine self&#62;&#62;;
 
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           default: "~Commands are on, off or a time of day only, pliz.~";
 
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       ],
 
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       life
 
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       [;  Ask, Answer, Tell:
 
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              "[Try ~clock, something~ to address the clock.]";
 
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       ],
 
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  has  talkable;
 
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</PRE>
 
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and add a new verb to the grammar:
 
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<PRE>
 
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Verb "alarm," * "on"      -&#62; SwitchOn
 
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              * "off"     -&#62; SwitchOff
 
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              * TimeOfDay -&#62; SetTo;
 
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</PRE>
 
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(using the <TABLE Border><TR><TD><TT>TimeOfDay</TT></TABLE> token from the exercises of <A HREF="section27.html">Section 27</A>).  Note
 
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that since the word "alarm,'' can't be matched by anything the player types,
 
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this verb is concealed from ordinary grammar.  The orders we produce here
 
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are not used in the ordinary way (for instance, the action <TT>SwitchOn</TT> with
 
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no <TT>noun</TT> or <TT>second</TT> would never ordinarily be produced by the parser) but this
 
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doesn't matter: it only matters that the grammar and the <TT>orders</TT> property
 
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agree with each other.
 
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</TABLE>
 
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<HR>Back to <A HREF="../section16.html#ex25">the exercise in section 16</A><HR>
 
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<SMALL><I>Mechanically translated to HTML from third edition as revised 16 May 1997. Copyright &#169; Graham Nelson 1993, 1994, 1995, 1996, 1997: all rights reserved.</I></SMALL></BODY></HTML>