Path: utzoo!attcan!uunet!lll-winken!ames!ncar!ico!rcd
From: rcd@ico.ISC.COM (Dick Dunn)
Newsgroups: comp.lang.misc
Subject: Re: Passing Values Through a "goto"
Summary: characteristic of assembly language
Message-ID: <13549@ico.ISC.COM>
Date: 12 Jan 89 00:43:32 GMT
References: <3300001@uxg.cso.uiuc.edu> <3290002@hpctdls.HP.COM> <8901070434.AA10471@yorkville.csri.toronto.edu>
Organization: Interactive Systems Corp, Boulder, CO
Lines: 21

Karl Heuer wrote:
> >Passing values through a goto doesn't seem to work well, since a label by
> >itself is not a valid statement...

Victor Greenberg responded:
> Although goto is questionable as a language feature, it isn't hard to
> generalize for use in an expression based language.  Instead of labelled
> statements, you want labelled *expressions*...

Another way to think of this is to consider assembly language; let's assume
it's for a stack-based processor just to make it easier.  At the point of a
label, you need to know that the stack has a particular configuration no
matter how you get to that label.  It is equivalent to having a particular
type associated with the label...and, in fact, one could imagine performing
a coercion on the values "sent" to the label.  This is akin to the
balancing coercion required in a conditional expression--and, in fact, if
you think of the conditional-jump implementation of a conditional
expression, you can see the balancing taking place in the generated code.
-- 
Dick Dunn      UUCP: {ncar,nbires}!ico!rcd           (303)449-2870
   ...Worst-case analysis must never begin with "No one would ever want..."