Date: Fri, 01 May 2009 22:55:39 +0200 From: Christoph Mallon <christoph.mallon@gmx.de> To: Marius Strobl <marius@alchemy.franken.de> Cc: Maxim Sobolev <sobomax@freebsd.org>, FreeBSD Hackers <freebsd-hackers@freebsd.org>, Roman Divacky <rdivacky@freebsd.org>, Ed Schouten <ed@freebsd.org>, Warner Losh <imp@freebsd.org> Subject: Re: C99: Suggestions for style(9) Message-ID: <49FB61CB.80906@gmx.de> In-Reply-To: <20090501121018.GC2943@alchemy.franken.de> References: <49F4070C.2000108@gmx.de> <20090501112239.GA23199@alchemy.franken.de> <49FADEF3.5010106@gmx.de> <20090501121018.GC2943@alchemy.franken.de>
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Marius Strobl schrieb:
> On Fri, May 01, 2009 at 01:37:23PM +0200, Christoph Mallon wrote:
>> Marius Strobl schrieb:
>>> On Sun, Apr 26, 2009 at 09:02:36AM +0200, Christoph Mallon wrote:
>>>> return with parentheses:
>>>> Removed, because it does not improve maintainability in any way. There
>>>> is no source for confusion here, so the rule even contradicts the rule,
>>>> which states not to use redundant parentheses. Maybe, decades ago it was
>>>> just a workaround for a broken compiler, which does not exist anymore.
>>> FYI, the idea behind this rule is said to be to able to use
>>> a macro return(), f.e. for debugging you then can do:
>>> #define return(x) do { \
>>> printf("returning from %s with %d\n", __func__, (x)); \
>>> return (x); \
>>> } while (0)
>>>
>>> Given the this is a nifty feature and parentheses around the
>>> return value don't hurt maintainability in any way IMO this
>>> rule should stay.
>> This is mentioned nowhere in style(9) (in general it is lacking reasons
>> why something is some way or the other).
>
> I agree that style(9) lacks explanations, however this doesn't
> necessarily mean that non-obvious rules are "silly" and should
> be removed.
I neither said not implied this. I said, that it is lacking in
justification, which clearly is bad.
>> Also I consider this as gross abuse: Macro names shall be in all
>> uppercase, so it is clear that there is a macro at work. Therefore
>> "return" is not a candidate. So this would violate yet another rule in
>> style(9) (the original return already violates the no-redundant
>> parentheses rule).
>> Also I would not mention __func__: there were objections against using
>> it in the past (though I, logically, prefer its use).
>
> In general this is correct, a return() macro (in which case
> the parentheses are not redundant) would be for local debugging
> only and not ever hit the tree just like any other printf()-
> debugging should not, so neither is relevant here. Besides,
> a macro without side effects, which a return() macro typically
> shouldn't have, is fine to be named all lowercase according
> to style(9).
So everybody has to pay with a small amount of obfuscation per return
for an obscure trick, which compared to the number of returns is never used.
Therefore I don't consider the return-macro convincing at all.
Christoph
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