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Re: Using braces on 'if'; Was: Re: Asan help request

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July 31, 2013 01:22
Re: Using braces on 'if'; Was: Re: Asan help request
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On 31 July 2013 02:56, Karl Williamson <> wrote:
> On 07/25/2013 02:19 AM, Nicholas Clark wrote:
>> I don't think that using a comma operator in void context just to avoid
>> needing braces is really worth it. It doesn't feel like idiomatic C.
> I agree, and I'd like to put in a plug for using braces.
> The coding standards where I $worked called for always using braces when the
> 'then' clause was not on the same line as its 'if'.  The reason was bitter
> experience with maintenance safety.  It's too easy for someone to later come
> in and fail to notice the absence of braces, and turn this:
>         if (a)
>            b;
> into
>         if (a)
>            c;
>            b;
> Thus causing b to be executed unconditionally, contrary to the original
> code.  If you're lucky this will generate a compiler warning or error (as
> happened to me on Saturday with the Perl core).  If you're somewhat less
> lucky, the regression tests will have adequate coverage and you'll find this
> problem almost immediately.  But if you're unlucky, this regression won't be
> found until an angry customer and boss are breathing down your neck.  Under
> such pressure (or even without), code reading may very easily fail to see
> what is the problem.  Our eyes look at the indentation, and not the lack of
> braces.  This happened enough that we banned the practice, and everybody got
> into the habit of always saying
>         if (a) {
>            b;
>         }
> That habit has saved me from creating many bugs over the years.


I almost always use braces in C, and often convert braceless Perl core
code to include the braces.

I dont think leaving out the braces wins enough for the risk, and it
makes it harder to switch back and forth between Perl and C.


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