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Re: [Qemu-devel] [PATCH] Document Qemu coding style
From: |
Blue Swirl |
Subject: |
Re: [Qemu-devel] [PATCH] Document Qemu coding style |
Date: |
Mon, 30 Mar 2009 21:28:54 +0300 |
On 3/30/09, Avi Kivity <address@hidden> 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 <address@hidden>
> ---
> 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!
- [Qemu-devel] [PATCH] Document Qemu coding style, Avi Kivity, 2009/03/29
- Re: [Qemu-devel] [PATCH] Document Qemu coding style, malc, 2009/03/29
- Re: [Qemu-devel] [PATCH] Document Qemu coding style,
Blue Swirl <=
- Re: [Qemu-devel] [PATCH] Document Qemu coding style, M. Warner Losh, 2009/03/30
- Re: [Qemu-devel] [PATCH] Document Qemu coding style, Avi Kivity, 2009/03/30
- Re: [Qemu-devel] [PATCH] Document Qemu coding style, Lennart Sorensen, 2009/03/30
- Re: [Qemu-devel] [PATCH] Document Qemu coding style, M. Warner Losh, 2009/03/30
- Re: [Qemu-devel] [PATCH] Document Qemu coding style, Lennart Sorensen, 2009/03/30
- Re: [Qemu-devel] [PATCH] Document Qemu coding style, M. Warner Losh, 2009/03/30
- Re: [Qemu-devel] [PATCH] Document Qemu coding style, Laurent Desnogues, 2009/03/31
- Re: [Qemu-devel] [PATCH] Document Qemu coding style, David Turner, 2009/03/31
- Re: [Qemu-devel] [PATCH] Document Qemu coding style, Avi Kivity, 2009/03/31