From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LoMEG-0006ap-GZ for qemu-devel@nongnu.org; Mon, 30 Mar 2009 14:29:00 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LoMEC-0006Zz-RP for qemu-devel@nongnu.org; Mon, 30 Mar 2009 14:29:00 -0400 Received: from [199.232.76.173] (port=46523 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LoMEC-0006Zs-Mb for qemu-devel@nongnu.org; Mon, 30 Mar 2009 14:28:56 -0400 Received: from mail-fx0-f169.google.com ([209.85.220.169]:53553) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1LoMEC-0002o8-2L for qemu-devel@nongnu.org; Mon, 30 Mar 2009 14:28:56 -0400 Received: by fxm17 with SMTP id 17so1898334fxm.34 for ; Mon, 30 Mar 2009 11:28:55 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1238361823-24939-1-git-send-email-avi@redhat.com> References: <1238361823-24939-1-git-send-email-avi@redhat.com> Date: Mon, 30 Mar 2009 21:28:54 +0300 Message-ID: Subject: Re: [Qemu-devel] [PATCH] Document Qemu coding style From: Blue Swirl Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org On 3/30/09, Avi Kivity wrote: > With the help of some Limoncino I noted several aspects of the Qemu coding > style, particularly where it differs from the Linux coding style as many > contributors work on both projects. Ok, I'm armed with some Foster's. > > Signed-off-by: Avi Kivity > --- > CODING_STYLE | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 files changed, 77 insertions(+), 0 deletions(-) > create mode 100644 CODING_STYLE > > diff --git a/CODING_STYLE b/CODING_STYLE > new file mode 100644 > index 0000000..54fdeff > --- /dev/null > +++ b/CODING_STYLE > @@ -0,0 +1,77 @@ > +Qemu Coding Style > +================= > + > +1. Whitespace > + > +Of course, the most important aspect in any coding style is whitespace. > +Crusty old coders who have trouble spotting the glasses on their noses > +can tell the difference between a tab and eight spaces from a distance > +of approximately fifteen parsecs. Many a flamewar have been fought and > +lost on this issue. > + > +Qemu indents are four spaces. Tabs are never used, except in Makefiles > +where they have been irreversibly coded into the syntax by some moron. > +Spaces of course are superior to tabs because: > + > + - You have just one way to specify whitespace, not two. Ambiguity breeds > + mistakes. > + - The confusion surrounding 'use tabs to indent, spaces to justify' is gone. > + - Tab indents push your code to the right, making your screen seriously > + unbalanced. > + - Tabs will be rendered incorrectly on editors who are misconfigured not > + to use tab stops of eight positions. > + - Tabs are rendered badly in patches, causing off-by-one errors in almost > + every line. > + - It is the Qemu coding style. Never leave whitespace at the end of line, it annoys the Quilt. Empty lines at the end of file just make files bigger. > + > +2. Line width > + > +Lines are 80 characters wide plus some slop. Try to fit your code into > +eighty characters, but if it makes a snippet particularly ugly, allow > +yourself some slack. Don't overdo it though. > + > +Rationale: > + - Some people like to tile their 24" screens with a 6x4 matrix of 80x24 > + xterms and use vi in all of them. The best way to punish them is to > + let them keep doing it. > + - Code and especially patches is much more readable if limited to a sane > + line length. Eighty is traditional. > + - It is the Qemu coding style. > + > +3. Naming > + > +Variables are lower_case_with_underscores; easy to type and read. Structured > +type names are in CamelCase; harder to type but standing out. Scalar type > +names are lower_case_with_underscores_ending_with_a_t, like the Posix > +uint64_t and family. > + > +Typedefs are used to eliminate the redundant 'struct' keyword. It is the > +Qemu coding style. > + > +4. Block structure > + > +Every indented statement is braced; even if the block contains just one > +statement. I'd remove this, braces are not used consistently for one statement blocks. > The opening brace is on the line that contains the control > +flow statement that introduces the new block; the closing brace is on the > +same line as the else keyword, or on a line by itself if there is no else > +keyword. Example: > + > + if (a == 5) { > + printf("a was 5.\n"); > + } else if (a == 6) { > + printf("a was 6.\n"); > + } else { > + printf("a was something else entirely.\n"); > + } > + > +An exception is the opening brace for a function; for reasons of tradition > +and clarity it comes on a line by itself: > + > + void a_function(void) > + { > + do_something(); > + } > + > +Rationale: a consistent (except for functions...) bracing style reduces > +ambiguity and avoids needless churn when lines are added or removed. > +Furthermore, it is the Qemu coding style. No, this is the K&R style. Quoting linux/Documentation/CodingStyle: Heretic people all over the world have claimed that this inconsistency is ... well ... inconsistent, but all right-thinking people know that (a) K&R are _right_ and (b) K&R are right. Besides, functions are special anyway (you can't nest them in C). Cheers!