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From: karl@haddock.ISC.COM (Karl Heuer)
Newsgroups: comp.lang.c
Subject: Re: goto's and switch statements -- mild proposal
Message-ID: <929@haddock.ISC.COM>
Date: Wed, 12-Aug-87 17:02:34 EDT
Article-I.D.: haddock.929
Posted: Wed Aug 12 17:02:34 1987
Date-Received: Sat, 15-Aug-87 01:48:37 EDT
References: <855@tjalk.cs.vu.nl> <2683@hoptoad.uucp> <916@haddock.ISC.COM> <2182@zeus.TEK.COM>
Reply-To: karl@haddock.ima.isc.com (Karl Heuer)
Organization: Interactive Systems, Boston
Lines: 21

In article <2182@zeus.TEK.COM> dant@tekla.UUCP (Dan Tilque) writes:
>[If switch statements had automatic break instead of fall-through, the
>current idiom "case CR: case LF: ..." wouldn't work.]  One possibility is
>separating them with commas: "case CR, LF, TAB, ' ':" which changes the
>meaning of the comma operator.  Probably not a good idea.

The comma operator is neither necessary nor useful in a constant expression,
and is explicitly disallowed by ANSI.

>However, I agree that it's bad programming to have this kind of thing:
>"case 'a':   a = b + count;   case 'b':   count += 2;".  Lint should
>definitely give warning since it's almost always the case that what's desired
>is a break before case 'b':.  Also, one of my more frequent mistakes is
>leaving breaks out of switches.

I agree, but (failing something stronger, such as my proposal) it should be
possible to turn off this warning, since some people intentionally write the
above.  A lintpragma /* FALLTHROUGH */ is the simplest solution.  I think some
implementations already have this.

Karl W. Z. Heuer (ima!haddock!karl or karl@haddock.isc.com), The Walking Lint