Date: Fri, 05 Jun 1998 11:26:17 +0200 (CEST) From: Marino Ladavac <lada@pc8811.gud.siemens.at> To: Greg Lehey <grog@lemis.com> Cc: freebsd-hackers@FreeBSD.ORG, Chris Csanady <cc@swing.ca.sandia.gov> Subject: Re: style(9) error? Message-ID: <XFMail.980605112617.lada@pc8811.gud.siemens.at> In-Reply-To: <19980605152726.G768@freebie.lemis.com>
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On 05-Jun-98 Greg Lehey wrote:
> On Thu, 4 June 1998 at 16:22:22 -0500, Chris Csanady wrote:
>>
>> I would like to make use of a feature that style tells me I can use, but
>> gcc tells me I can not..
>>
>>> From style(9):
>>
>> es, it makes it easier to read. If the macro encapsulates a compound
>> statement, enclose it in a ``do'' loop, so that it can safely be used
>> in
>> ``if'' statements. Any final statement-terminating semicolon should be
>> supplied by the macro invocation rather than the macro, to make parsing
>> easier for pretty-printers and editors.
>>
>> #define MACRO(x, y) do {
>> #\
>> variable = (x) + (y);
>> \
>> (y) += 2;
>> \
>> } while(0)
>>
>> As far as I can tell, it is impossible to put a do loop in a if statement,
>> or anything else. Is this correct?
>
> No.
We have a case of misunderstanding here: the original poster asked whether
if (MACRO(x, y))
foo();
else
bar();
were allowed (which it is not, with the MACRO defined as it is), whereas
you and the manpage are refering to
if (foo())
MACRO(x, y);
else
MACRO(y, x);
which is, and the do {} while() loop MACRO construct is necessary in order
to allow for semicolons after the MACRO invocation in a true or false branches
of an if statement.
/Marino
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