Hi,
> Subject: Re: [PATCH v2 1/8] CODING_STYLE: Section about conditional
> statement
>
> On 07/31/2014 08:32 PM, arei.gong...@huawei.com wrote:
> > From: Gonglei <arei.gong...@huawei.com>
> >
> > Yoda conidtions lack of readability, and QEMU have a
>
> s/conidtions/conditions/
> s/of //
> s/have/has/
>
OK.
> > strict compiler configuration for checking a common
> > mistake like "if (dev = NULL)". Make it a written rule.
> >
> > Signed-off-by: Gonglei <arei.gong...@huawei.com>
> > ---
> > CODING_STYLE | 19 +++++++++++++++++++
> > 1 file changed, 19 insertions(+)
> >
> > diff --git a/CODING_STYLE b/CODING_STYLE
> > index 4280945..11a79d4 100644
> > --- a/CODING_STYLE
> > +++ b/CODING_STYLE
> > @@ -91,3 +91,22 @@ Mixed declarations (interleaving statements and
> declarations within blocks)
> > are not allowed; declarations should be at the beginning of blocks. In
> other
> > words, the code should not generate warnings if using GCC's
> > -Wdeclaration-after-statement option.
> > +
> > +6. Conditional statement
>
> s/statement/statements/
>
OK.
> > +
> > +Please don't use Yoda conditions because of lack of readability.
> > Furthermore,
> > +it is not the QEMU idiomatic coding style. Example:
> > +
> > +Usually a conditional statement in QEMU would be written as:
> > +if (a == 0) {
> > + /* Reads like: "If a is equal to 0..." */
> > + do_something();
> > +}
> > +
> > +Yoda conditions describe the same expression, but reversed:
> > +if (0 == a) {
> > + /* Reads like: "If 0 equals to a" */
> > + do_something();
> > +}
> > +
> > +The constant is listed first, then the variable being compared to.
> >
>
> This spends more lines documenting the bad style than the good, and
> doesn't quite flow with the rest of the document. At the risk of
> sounding like a complete rewrite, how about:
>
> =====
> When comparing a variable for (in)equality with a constant, list the
> constant on the right, as in:
>
> if (a == 0) {
> do_something();
> }
>
> Rationale: Yoda conditionals (as in 'if (0 == a)') are awkward to read.
> Besides, good compilers already warn users when == is mis-typed as =,
> even when the constant is on the right.
> =====
>
Good description.
> and maybe some other ideas also worth adding:
>
> =====
> Avoid redundant comparisons: (bool_expr == true) is better written as
> (bool_expr), and (ptr == NULL) is shorter as (!ptr). Use of !!value is
> a convenient shorthand for converting a value into a boolean.
> =====
>
Agreed. Thanks!
Best regards,
-Gonglei
