> From: Bruce Richardson [mailto:bruce.richard...@intel.com]
> Sent: Wednesday, 3 May 2023 12.57
>
> On Wed, May 03, 2023 at 11:30:53AM +0100, Ferruh Yigit wrote:
> > Declaring variable inside for loop is not supported via C89 and it was
> > checked in checkpatch.sh via commit [1].
> > But as DPDK supported C standard is becoming C99/C11 [2], declaring
> > variable inside loop can be allowed.
> >
> > [1]
> > Commit 43e73483a4b8 ("devtools: forbid variable declaration inside
> for")
> >
> > [2]
> > https://dpdk.org/patch/121912
> >
> > Signed-off-by: Ferruh Yigit <ferruh.yi...@amd.com>
> > ---
> > Cc: Bruce Richardson <bruce.richard...@intel.com>
> > Cc: David Marchand <david.march...@redhat.com>
> >
> > v2:
> > * Update coding convention too
> > ---
>
> Acked-by: Bruce Richardson <bruce.richard...@intel.com>
Acked-by: Morten Brørup <m...@smartsharesystems.com>
[...]
> > @@ -558,6 +558,7 @@ Local Variables
> >
> > * Variables should be declared at the start of a block of code rather
> than in the middle.
>
> I'd love to see this restriction removed in future too. Having a
> variable
> declared on first use in the middle of block I find a far easier way of
> working as a) it saves scrolling to look for variable definitions and b)
> it
> makes it far easier when adding/removing blocks of code e.g. commenting
> out
> for testing, to have all the code together rather than having variables
> at
> the top to add/remove also.
And c) Initializing the variables close to where they are used the first time
reduces the risk of initializing them incorrectly. Especially when modifying a
block of code, initialization of its variables might be missed if out of sight.
(Although this is probably a consequence of "a)".)
I consider it old style to only declare variables at the start of a block of
code, and this style of coding should be considered obsolete.
If you are really old (like me?), you might remember when function parameters
were provided like this:
int main(argc, argv)
int argc;
char *argv[];
{
return(0);
}
We have moved on from that to a more modern coding style a long time ago. We
should also move on to a more modern coding style regarding variable
declarations.
>
> > The exception to this is when the variable is ``const`` in which
> case the declaration must be at the point of first use/assignment.
> > + Declaring variable inside a for loop is OK.
> > * When declaring variables in functions, multiple variables per line
> are OK.
> > However, if multiple declarations would cause the line to exceed a
> reasonable line length, begin a new set of declarations on the next line
> rather than using a line continuation.
> > * Be careful to not obfuscate the code by initializing variables in
> the declarations, only the last variable on a line should be
> initialized.
> > --
> > 2.34.1
> >
