linux-kernel - Re: checkpatch guide for newbies

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Message-ID: <CAErSpo4X0-PEYtZrY2r4GKmzTJhHK3eKdXrbccJhB7wVkVCYLA@mail.gmail.com>
Date:	Tue, 24 Sep 2013 14:13:26 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Peter Senna Tschudin <peter.senna@...il.com>
Cc:	Alexander Holler <holler@...oftware.de>,
	Dan Carpenter <dan.carpenter@...cle.com>,
	kernel-janitors@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: checkpatch guide for newbies

On Tue, Sep 24, 2013 at 1:29 PM, Peter Senna Tschudin
<peter.senna@...il.com> wrote:
> On Tue, Sep 24, 2013 at 7:26 PM, Alexander Holler <holler@...oftware.de> wrote:
>>> On Mon, Sep 23, 2013 at 3:01 AM, Dan Carpenter <dan.carpenter@...cle.com>
>>> wrote:
>>>>
>>>>                  Long Lines
>>>>
>>>> Historically screens were 80 characters wide and it was annoying when
>>>> code went
>>>> over the edge.  These days we have larger screens, but we keep the 80
>>>> character
>>>> limit because it forces us to write simpler code.
>>
>> Sorry, but that just isn't true and never was. Having a line wide limit of
>> 80 characters while forcing tabs to be 8 characters long limits most code to
>> just 72 characters. And even less (max 64) inside constructs like if, for or
>> while.
>>
>> The only outcome of that totally silly rule is that variable names will
>> become shorted to silly acronyms almost nobody does understand make code
>> unreadable.

In the context of a two-sentence paragraph, Dan's original text is
pithy and accurate.  A Wikipedia article would deserve more
elaboration.

Obviously the skill of the programmer is the overwhelming factor, but
I think restricting the line length does help encourage simpler,
better-factored code.  It's also part of the whole "it's better to be
consistent than to be better" thing.  If 95% of the files in Linux use
80-character lines and the remainder use longer lines, it's just an
ongoing hassle for the reader.

>> I always feel like beeing in the IT stone age when programmers thought they
>> have to use variable names like a, b and c to save storage, memory or to
>> type less when reading linux kernel code.
> I was about to disagree because I've never seen variables named a, b
> or c, but I found that there are at least 2238 variables named a, b or
> c in linux-next. This is not good.

That is not self-evident.  In many cases, e.g., loop iterators, simple
names are fine.  Nothing is gained by renaming a loop counter from "a"
to "array_index."  Simple names for simple things help the reader
focus on more important aspects of the code.

Bjorn
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