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From: edp@jareth.enet.dec.com (Eric Postpischil (Always mount a scratch monkey.))
Newsgroups: comp.sys.handhelds
Subject: Re: CLEAR-TO-MARK code
Message-ID: <19546@shlump.nac.dec.com>
Date: 29 Jan 91 13:50:29 GMT
References: <3306@gmuvax2.gmu.edu>
Sender: newsdaemon@shlump.nac.dec.com
Reply-To: edp@jareth.enet.dec.com (Eric Postpischil (Always mount a scratch monkey.))
Organization: Digital Equipment Corporation
Lines: 21

In article <3306@gmuvax2.gmu.edu>, peraino@gmuvax2.gmu.edu (Bob Peraino)
writes:

>     I simply cannot imagine how a program can be written to have no idea
>what it has thrown up on the stack.

ROOT is an example.  The user gives root some arguments that include an object
to be evaluated.
ROOT evaluates that object repeatedly for different values of some variable. 
Sometimes an error is generated.  ROOT must trap this error and clean up the
stack.

To be sure, CLEAR is not necessary; remembering the initial stack depth is
sufficient.

Another reason CLEAR might be desirable is when speed is important.


				-- edp (Eric Postpischil)
				"Always mount a scratch monkey."
				edp@jareth.enet.dec.com