Re: allowing multiple PQclear() calls

On Tue, Dec 11, 2012 at 5:18 AM, Boszormenyi Zoltan <zb@cybertec.at> wrote:
> 2012-12-11 12:45 keltezéssel, Simon Riggs írta:
>
>> On 11 December 2012 10:39, Marko Kreen <markokr@gmail.com> wrote:
>>>
>>> On Tue, Dec 11, 2012 at 6:59 AM, Josh Kupershmidt <schmiddy@gmail.com>
>>> wrote:
>>>>
>>>> Would it be crazy to add an "already_freed" flag to the pg_result
>>>> struct which PQclear() would set, or some equivalent safety mechanism,
>>>> to avoid this hassle for users?
>>>
>>> Such mechanism already exist - you just need to set
>>> your PGresult pointer to NULL after each PQclear().
>>
>> So why doesn't PQclear() do that?
>
>
> Because then PQclear() would need a ** not a *. Do you want its
> interface changed for 9.3 and break compatibility with previous versions?
> Same can be said for e.g. PQfinish(). Calling it again crashes your client,
> as I have recently discovered when I added atexit() functions that
> does "if (conn) PQfinish(conn);"  and the normal flow didn't do conn = NULL;
> after it was done.

Ah, well. I guess using a macro like:

#define SafeClear(res) do {PQclear(res); res = NULL;} while (0);

will suffice for me.

Josh