[Python-Dev] Re: Proposal: C API Macro to decref and set to NULL

[David Abrahams]

Tim Peters <tim.peters at gmail.com> writes:

> [Jim Fulton]
> ...
>> If there are no objections I'll add the following definition to object.h,
>> after the definition for Py_DECREF:
>> 
>> #define Py_CLEAR(op)                            \
>>         do {                                   \
>>                 if (op) {                      \
>>                         PyObject *tmp = (op);  \
>>                         (op) = NULL;           \
>>                         Py_DECREF(tmp);                \
>>                 }                              \
>>         } while (0)
>> 
>> and update the docs and the tutorial on creating types in C.
>
> +1.  At least pystate.c can get rid of its functionally identical
> private ZAP macro then.

FWIW our experience in the C++ community suggests that
deallocate-and-NULL tends to hide bugs.  In general we prefer to use
deallocate-and-fill-pointer-with-garbage.  I'm not sure if the
experience translates here, of course.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com