Re: Dangling else

Marco van de Voort <marcov@stack.nl>
15 Mar 2006 22:11:19 -0500

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Related articles
[11 earlier articles]
Re: Dangling else rsc@swtch.com (Russ Cox) (2006-03-06)
Re: Dangling else marcov@stack.nl (Marco van de Voort) (2006-03-11)
Re: Dangling else Brian.Inglis@SystematicSW.ab.ca (Brian Inglis) (2006-03-11)
Re: Dangling else henry@spsystems.net (2006-03-14)
Re: Dangling else 148f3wg02@sneakemail.com (Karsten Nyblad) (2006-03-15)
Re: Dangling else DrDiettrich@compuserve.de (Hans-Peter Diettrich) (2006-03-15)
Re: Dangling else marcov@stack.nl (Marco van de Voort) (2006-03-15)
Re: Dangling else henry@spsystems.net (2006-03-16)
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From: Marco van de Voort <marcov@stack.nl>
Newsgroups: comp.compilers
Date: 15 Mar 2006 22:11:19 -0500
Organization: Stack Usenet News Service
References: 06-02-154 06-02-168 06-03-008 06-03-023 06-03-041
Keywords: syntax
Posted-Date: 15 Mar 2006 22:11:19 EST

On 2006-03-14, Henry Spencer <henry@spsystems.net> wrote:
> No, I'm thinking of things like `(x < y) and (q > 4)', where the
> parentheses are mandatory because the Boolean-condition operators
> share the precedence levels of the arithmetic operators rather than
> having their own.


> Wirth himself, in his 1975 Pascal retrospective ("An assessment of the
> programming language Pascal", IEEE TransSoftEng 1.2, June 1975), said:
> "In retrospect... the decision to break with a widely used tradition seems
> ill-advised..."


Well, I had no formal boolean math classes before being exposed to
Pascal, so I can't fully judge that.


However I think a case could be made for consistency as much as for
legacy. Specially since in practice hordes of programmers just choose
to avoid these problems, parenthese each ambiguous case anyway, in any
language. (and by that "ambiguous" I mean as decided in a split
second, no thorough analysis of typing, scope and expression).


This shows that the field of software engineering and mathematics are
simply not fully equivalent. YMMV depending on personal history of
course.

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