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From: worley@compass.com (Dale Worley)
Newsgroups: comp.lang.perl
Subject: Sluggish patterns.
Message-ID: <1991Apr5.194345.10811@uvaarpa.Virginia.EDU>
Date: 5 Apr 91 19:43:45 GMT
Sender: mmdf@uvaarpa.Virginia.EDU (Uvaarpa Mail System)
Reply-To: worley@compass.com
Organization: The Internet
Lines: 44


   From: flee@cs.psu.edu (Felix Lee)

   Okay.  Now how do you make it recursive?
	   sub ctw {
		   local($cookie, $monster) = @_;
		   while (! $done) {
			   &eat() if /$cookie/;
			   &run() if /$monster/;
		   }
	   }
   $cookie and $monster change infrequently, but they may change in
   either &eat or &run.  Either &eat or &run may call &ctw recursively
   with random parameters.

The following code comes to mind, although I don't know if it is correct:

   $old_cookie = $old_monster = 'something invalid';

   sub ctw {
	   local($cookie, $monster) = @_;
	   local($old_cookie, $old_monster);
	   local(*cookie, *monster);

	   while (! $done) {
		   eval "sub cookie { &eat() if /$cookie/o; }"
			if $cookie ne $old_cookie;
		   &eat() if /$cookie/;
		   eval "sub monster { &run() if /$monster/o; }"
			if $monster ne $old_monster;
		   &run() if /$monster/;
	   }
   }

When a recursive call of ctw occurs, &cookie and &monster are saved,
along with $old_cookie and $old_monster.

Dale

Dale Worley		Compass, Inc.			worley@compass.com
--
He divines remedies against injuries; he knows how to turn serious accidents
to his own advantage; whatever does not kill him makes him stronger.
-- Friedrich Nietzsche