[Python-Dev] cpython: Remove some extraneous parentheses and swap the comparison order to

[Brett Cannon]

On Mon, Jun 6, 2011 at 23:57, Georg Brandl <g.brandl at gmx.net> wrote:

> On 06/07/11 05:20, brett.cannon wrote:
> > http://hg.python.org/cpython/rev/fc282e375703
> > changeset:   70695:fc282e375703
> > user:        Brett Cannon <brett at python.org>
> > date:        Mon Jun 06 20:20:36 2011 -0700
> > summary:
> >   Remove some extraneous parentheses and swap the comparison order to
> > prevent accidental assignment.
> >
> > Silences a warning from LLVM/clang 2.9.
>
> Swapping the comparison order here seems a bit inconsistent to me. There
> are
> lots of others around (e.g. "len == 0" in the patch context below). Why is
> this one so special?
>
>
Old habit on how to do comparisons in C. Because C treats assignment as an
expression it means comparisons can accidentally become an assignment if you
accidentally leave out an = sign. By reversing this order it is simply not
possible to have that silent bug and instead you would get a compiler error
about trying to assign to a constant.

I'll revert that part of the change.


> I think that another developer even got told off once for these kinds of
> comparisons.
>
> I hope the Clang warning is only about the parentheses.
>

Yes, Clang only warned about the parentheses.

-Brett


>
> Georg
>
> > files:
> >   Modules/arraymodule.c |  2 +-
> >   1 files changed, 1 insertions(+), 1 deletions(-)
> >
> >
> > diff --git a/Modules/arraymodule.c b/Modules/arraymodule.c
> > --- a/Modules/arraymodule.c
> > +++ b/Modules/arraymodule.c
> > @@ -2091,7 +2091,7 @@
> >      if (len == 0) {
> >          return PyUnicode_FromFormat("array('%c')", (int)typecode);
> >      }
> > -    if ((typecode == 'u'))
> > +    if ('u' == typecode)
> >          v = array_tounicode(a, NULL);
> >      else
> >          v = array_tolist(a, NULL);
>
>
>
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