From: "Morten Brørup" <mb@smartsharesystems.com>
To: "Bruce Richardson" <bruce.richardson@intel.com>,
"Ferruh Yigit" <ferruh.yigit@amd.com>
Cc: "Thomas Monjalon" <thomas@monjalon.net>, <dev@dpdk.org>,
"David Marchand" <david.marchand@redhat.com>
Subject: RE: [PATCH v2] devtools: allow variable declaration inside for loop
Date: Wed, 3 May 2023 14:19:30 +0200 [thread overview]
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35D878DC@smartserver.smartshare.dk> (raw)
In-Reply-To: <ZFI9/n0KMDIBsEvx@bricha3-MOBL.ger.corp.intel.com>
> From: Bruce Richardson [mailto:bruce.richardson@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.yigit@amd.com>
> > ---
> > Cc: Bruce Richardson <bruce.richardson@intel.com>
> > Cc: David Marchand <david.marchand@redhat.com>
> >
> > v2:
> > * Update coding convention too
> > ---
>
> Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Morten Brørup <mb@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
> >
next prev parent reply other threads:[~2023-05-03 12:19 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-03 9:50 [PATCH v1] " Ferruh Yigit
2023-05-03 10:02 ` Bruce Richardson
2023-05-03 10:23 ` Ferruh Yigit
2023-05-03 10:30 ` [PATCH v2] " Ferruh Yigit
2023-05-03 10:57 ` Bruce Richardson
2023-05-03 12:19 ` Morten Brørup [this message]
2023-05-03 15:01 ` Thomas Monjalon
2023-05-03 15:06 ` Tyler Retzlaff
2023-07-20 4:05 ` Thomas Monjalon
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