[Qemu-devel] [PATCH] Document QEMU coding style (v2)

[Qemu-devel] [PATCH] Document QEMU coding style (v2)

[Avi Kivity]

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 <avi@redhat.com>

Changes from v1:
  - s/Qemu/QEMU/
  - s/Posix/POSIX/
  - note that the _t suffix is not POSIX compliant, and will be changed
  - discourage eol whitespace
  - be strict about the 80 char line width
---
 CODING_STYLE |   78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 78 insertions(+), 0 deletions(-)
 create mode 100644 CODING_STYLE

diff --git a/CODING_STYLE b/CODING_STYLE
new file mode 100644
index 0000000..1ab13b6
--- /dev/null
+++ b/CODING_STYLE
@@ -0,0 +1,78 @@
+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.
+
+Do not leave whitespace dangling off the ends of lines.
+
+2. Line width
+
+Lines are 80 characters; not longer.
+
+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.  Note that this last convention contradicts POSIX
+and is therefore likely to be changed.
+
+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

Re: [Qemu-devel] [PATCH] Document QEMU coding style (v2)

[Edgar E. Iglesias]

On Tue, Mar 31, 2009 at 08:23:06PM +0300, 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.
> 
> Signed-off-by: Avi Kivity <avi@redhat.com>
> 
> Changes from v1:
>   - s/Qemu/QEMU/
>   - s/Posix/POSIX/
>   - note that the _t suffix is not POSIX compliant, and will be changed
>   - discourage eol whitespace
>   - be strict about the 80 char line width
> ---
>  CODING_STYLE |   78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 78 insertions(+), 0 deletions(-)
>  create mode 100644 CODING_STYLE
> 
> diff --git a/CODING_STYLE b/CODING_STYLE
> new file mode 100644
> index 0000000..1ab13b6
> --- /dev/null
> +++ b/CODING_STYLE
> @@ -0,0 +1,78 @@
> +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:


Hi I'd appreciate it if we removed the insults and the arrogance, i.e
skip the "moron" and the of courses. Other than that most of this stuff
looks acceptable to me, although I don't necessarily agree with all of
it :)

Thanks


> +
> + - 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.
> +
> +Do not leave whitespace dangling off the ends of lines.
> +
> +2. Line width
> +
> +Lines are 80 characters; not longer.
> +
> +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.  Note that this last convention contradicts POSIX
> +and is therefore likely to be changed.
> +
> +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
> 
> 

Re: [Qemu-devel] [PATCH] Document QEMU coding style (v2)

[Laurent Vivier]

Le mercredi 01 avril 2009 à 15:38 +0200, Edgar E. Iglesias a écrit :
> On Tue, Mar 31, 2009 at 08:23:06PM +0300, 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.
> > 
> > Signed-off-by: Avi Kivity <avi@redhat.com>
> > 
> > Changes from v1:
> >   - s/Qemu/QEMU/
> >   - s/Posix/POSIX/
> >   - note that the _t suffix is not POSIX compliant, and will be changed
> >   - discourage eol whitespace
> >   - be strict about the 80 char line width
> > ---
> >  CODING_STYLE |   78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 files changed, 78 insertions(+), 0 deletions(-)
> >  create mode 100644 CODING_STYLE
> > 
> > diff --git a/CODING_STYLE b/CODING_STYLE
> > new file mode 100644
> > index 0000000..1ab13b6
> > --- /dev/null
> > +++ b/CODING_STYLE
> > @@ -0,0 +1,78 @@
> > +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:
> 
> 
> Hi 

Hi,

> I'd appreciate it if we removed the insults and the arrogance, i.e
[...]

Perhaps it is humor ?

(Limoncino doesn't help...)


Regards,
Laurent
-- 
------------------ Laurent.Vivier@bull.net  ------------------
"Tout ce qui est impossible reste à accomplir"    Jules Verne
"Things are only impossible until they're not" Jean-Luc Picard

Re: [Qemu-devel] [PATCH] Document QEMU coding style (v2)

[John Haxby]

Laurent Vivier wrote:
> Le mercredi 01 avril 2009 à 15:38 +0200, Edgar E. Iglesias a écrit :
>   
>> On Tue, Mar 31, 2009 at 08:23:06PM +0300, Avi Kivity wrote:
>>     
>>> +
>>> +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:
>>>       
>> Hi 
>>     
>
> Hi,
>
>   
>> I'd appreciate it if we removed the insults and the arrogance, i.e
>>     
> [...]
>
> Perhaps it is humor ?
>
>   
I don't think so.  Stuart Feldman won an ACM award for Make: 
http://www.acm.org/announcements/softwaresystemaward.3-24-04.html.   
Merely disliking something does not make its author a moron.

jch

Re: [Qemu-devel] [PATCH] Document QEMU coding style (v2)

[malc]

On Wed, 1 Apr 2009, Edgar E. Iglesias wrote:

> On Tue, Mar 31, 2009 at 08:23:06PM +0300, 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.
> > 
> > Signed-off-by: Avi Kivity <avi@redhat.com>
> > 
> > Changes from v1:
> >   - s/Qemu/QEMU/
> >   - s/Posix/POSIX/
> >   - note that the _t suffix is not POSIX compliant, and will be changed
> >   - discourage eol whitespace
> >   - be strict about the 80 char line width
> > ---
> >  CODING_STYLE |   78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 files changed, 78 insertions(+), 0 deletions(-)
> >  create mode 100644 CODING_STYLE
> > 
> > diff --git a/CODING_STYLE b/CODING_STYLE
> > new file mode 100644
> > index 0000000..1ab13b6
> > --- /dev/null
> > +++ b/CODING_STYLE
> > @@ -0,0 +1,78 @@
> > +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:
> 
> 
> Hi I'd appreciate it if we removed the insults and the arrogance, i.e
> skip the "moron" and the of courses. Other than that most of this stuff

Seconded.

> looks acceptable to me, although I don't necessarily agree with all of
> it :)

[..snip..]

-- 
mailto:av1474@comtv.ru

Re: [Qemu-devel] [PATCH] Document QEMU coding style (v2)

[Avi Kivity]

John Haxby wrote:
>> Perhaps it is humor ?
>>   
> I don't think so.  Stuart Feldman won an ACM award for Make: 
> http://www.acm.org/announcements/softwaresystemaward.3-24-04.html.   
> Merely disliking something does not make its author a moron.

I didn't think would be it needed to be said, but of course the intent 
was humorous.

If people find it offensive I can remove it though.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

[Qemu-devel] Re: [PATCH] Document QEMU coding style (v2)

[Anthony Liguori]

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.
>
> Signed-off-by: Avi Kivity <avi@redhat.com>

Applied.  Thanks.

Regards,

Anthony Liguori