From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Lo2TK-0002bP-4f for qemu-devel@nongnu.org; Sun, 29 Mar 2009 17:23:14 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Lo2TE-0002Vz-OY for qemu-devel@nongnu.org; Sun, 29 Mar 2009 17:23:12 -0400 Received: from [199.232.76.173] (port=52529 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Lo2TE-0002Vk-Bq for qemu-devel@nongnu.org; Sun, 29 Mar 2009 17:23:08 -0400 Received: from mx2.redhat.com ([66.187.237.31]:43700) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1Lo2TD-0005ML-Sf for qemu-devel@nongnu.org; Sun, 29 Mar 2009 17:23:08 -0400 From: Avi Kivity Date: Mon, 30 Mar 2009 00:23:43 +0300 Message-Id: <1238361823-24939-1-git-send-email-avi@redhat.com> Subject: [Qemu-devel] [PATCH] Document Qemu coding style Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: qemu-devel@nongnu.org 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. 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. + +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. 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. -- 1.6.1.1