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From: karl@haddock
Newsgroups: net.lang.c
Subject: Re: Orphaned Response
Message-ID: <86900024@haddock>
Date: Fri, 22-Aug-86 13:43:00 EDT
Article-I.D.: haddock.86900024
Posted: Fri Aug 22 13:43:00 1986
Date-Received: Fri, 22-Aug-86 22:15:28 EDT
References: <1133@ttrdc.UUCP>
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Nf-From: haddock!karl    Aug 22 13:43:00 1986


ttrdc!levy (Dan Levy) writes:
>whatsa matter with "#define biff(pow) { if (pow) kayo(); else oof(); }"?

Since biff is now a complete statement (no trailing semicolon required), you
still can't write "if (...) biff(pow); else ...".  You could leave out the
semicolon, but this requires the user to know that biff is implemented this
way.  This is why the unusual definition "do {...} while (0)" (no trailing
semicolon) has been offered.

Ideally, it's nice for a macro to be an expression, since the function call
it resembles is an expression.  Thus ?: is preferred when possible.  (It is
evidently *not* possible in some compilers yet.)

>Bright (et al) have been saying "change the definition of C to allow this."

It's not clear whether this involves a change in the definition, or just a
bug fix in some existing compilers.

Karl W. Z. Heuer (ihnp4!ima!haddock!karl), The Walking Lint