linux-kernel - Re: [Patch] tty: move a definition out of switch block

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Date:	Thu, 3 Dec 2009 08:18:11 -0700
From:	Joe Peterson <joe@...rush.com>
To:	Cong Wang <amwang@...hat.com>
Cc:	Alan Cox <alan@...ux.intel.com>, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, Greg Kroah-Hartman <gregkh@...e.de>
Subject: Re: [Patch] tty: move a definition out of switch block

On Thu, Dec 3, 2009 at 01:36, Cong Wang <amwang@...hat.com> wrote:
> Generally putting variables local in the local scope is fine, but
> not for 'switch' block, to be more precisely, not for the case
> where putting local variables between 'switch' and its _first_
> label, IMO.

It is fine to declare variables at the start of a switch statement.
What *is* incorrect is either initializing such declared variables
(they won't get initialized) or declaring variables *after* a case
label (throws a compile error).

> It can lead to misunderstanding easily, since 'switch'
> jumps to its first label at a first glance. I know in this case
> the code is _not_ wrong, but again, it's not good for reading.

I would think the declaration inside the start of the switch block
would just indicate to the reader that the variable is local to the
switch block scope.

> Also, there's no conflicts if we put it out of 'switch' block.

But then the scope of these variables becomes larger than it need be.

-Joe
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