Date: Thu, 7 Mar 2002 15:53:15 -0500 From: Leo Bicknell <bicknell@ufp.org> To: Garance A Drosihn <drosih@rpi.edu> Cc: "Brian T.Schellenberger" <bts@babbleon.org>, hackers@FreeBSD.ORG Subject: Re: RFC: style(9) isn't explicit about booleans for testing -- an actual analysis of the code! Message-ID: <20020307205315.GA21048@ussenterprise.ufp.org> In-Reply-To: <p05101508b8ad7b67c653@[128.113.24.47]> References: <52204.1015480748@critter.freebsd.dk> <20020307071630.E26DBBA03@i8k.babbleon.org> <p05101508b8ad7b67c653@[128.113.24.47]>
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In a message written on Thu, Mar 07, 2002 at 03:27:49PM -0500, Garance A Drosihn wrote:
> As to the wording, PHK suggested that the wording for this
> rule in style(9) be changed:
> - - -
> get rid of the word boolean, ie: change
> Do not use ! for tests unless it is a boolean, e.g. use
> to
> Do not use ! for tests unless it is an integer type, e.g. use
Although C doesn't have the type "boolean", I believe this is a
conceptual distinction. That is, we don't want to allow this:
if (!uid) {
/* do thing only root can do */
}
Because UID is not a boolean type. It takes a range of values,
and should be:
if (uid == 0) {
/* do thing only root can do */
}
The only proper use of "!" is on a boolean type, defined as a type
that has two values, 0, and everything else.
Personally, I would clarify boolean in the document as follows:
C does not provide a proper boolean type. As a result, FreeBSD
uses integers for a boolean type. The boolean values are 0 for
false, and all other values for true. All code using a boolean
type must not depend on "true" having any specific value.
--
Leo Bicknell - bicknell@ufp.org - CCIE 3440
PGP keys at http://www.ufp.org/~bicknell/
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