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From: nraoaoc@nmt.edu (Daniel Briggs)
Newsgroups: comp.lang.fortran
Subject: Re: A Question of Style
Summary: GOTOs aren't the problem -- labels are!
Message-ID: <1991May22.212429.20215@nmt.edu>
Date: 22 May 91 21:24:29 GMT
References: <1991May21.140440.16964@m.cs.uiuc.edu> <1991May21.180713.1602@unixg.ubc.ca> <1991May22.093547.229@ktibv.uucp>
Reply-To: dbriggs@nrao.edu (Daniel Briggs)
Organization: National Radio Astronomy Observatory, Socorro NM
Lines: 40

buckland@ucs.ubc.ca (Tony Buckland) writes:
> There are a few people around (I'm not one of them, but I will
> defend, although not entirely to the death, their right to be
> themselves) who put labels on statements just as markers, with
> no intention of ever referencing them.  The technique can serve
> as a way of locating all statements belonging to some class
> defined in the programmer's head, or as a way of delineating
> program segments, or as a labelling of statements you intend
> to reference one day, or as a labelling of drop-through
> statements for computed GOTOs.  Et cetera.

While few people would use Numerical Recepies code as a model of good
coding style, there was one paragraph in the introduction of the book
that stuck with me ever since I first read it.  This argument alone is
enough to convince me to never use an unneeded statement label as a
shorthand for a precurser comment.

This is from page 6:

"Second, you {\it avoid}, insofar as possible, control statements
whose controlled blocks or objects are difficult to discern at a
glance.  This means, in practice, that {\it you must try to avoid
statement labels and {\tt GOTO}'s}.  It is not the {\tt GOTO}'s which
are dangerous (although they do interrupt one's reading of the
program); the statement labels are the hazard.  In fact, whenever you
encounter a statement label while reading a program, you will soon be
conditioned to get a sinking feeling in the pit of your stomach.  Why?
Because the following questions will, by habit, immediately spring to
mind: Where did control come {\it from} in a branch to this label?  It
could be anywhere in the routine!  What circumstances resulted in a
branch to this label?  They could be anything!  Certainty becomes
uncertainty, understanding dissolves into a morass of possibilities.

(For the uninitiated, {\it ...} and {\tt ...} are TeXisms for italic
and typewriter fonts.)  

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