[Python-Dev] Assign to errno allowed?

[Guido van Rossum]

> > Question.  You showed that errno was #defined as a call to the right
> > function.  Why don't you leave *getting* errno alone?
> 
> Sorry I forgot to clarify that part.
> 
> Windows CE 1 and 2 have "errno", but in CE 3.0 they improved 
> the OS by eliminating errno and replacing it with
> GetLastError()
> 
> I suspect this was done to allow CE to be embedded on new
> processor types that would not otherwise be supported.
> 
> 
> > You talk of 100s of places using errno.  But how many places *set*
> > errno?
> 
> In the modules dir, grep shows:
> 
> File cmathmodule.c:
>         Py_SetErrno(0);
> File cPickle.c:
>         Py_SetErrno(0);
>                 Py_SetErrno(0);
>         Py_SetErrno(0);
> File mathmodule.c:
>         Py_SetErrno(0);
>         Py_SetErrno(0);
>         Py_SetErrno(0);
>         Py_SetErrno(0);
>         Py_SetErrno(0);
> 
> But alas for the GetLastError() issue, this wouldn't be so bad.

Well, *that* is easily solved in pyport.h:

#ifdef ...WINCE...
#ifndef errno
#define errno GetLastError()
#endif
#endif

Much better than changing every use of errno, isn't it? :-)

--Guido van Rossum (home page: http://www.python.org/~guido/)