Message-ID: <50E457C4.40709@vmware.com>
Date: Wed, 02 Jan 2013 17:52:36 +0200
From: Heikki Linnakangas <hlinnakangas@vmware.com>
Organization: VMware
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To: Marko Kreen <markokr@gmail.com>
CC: Boszormenyi Zoltan <zb@cybertec.at>, Simon Riggs <simon@2ndquadrant.com>,
	Josh Kupershmidt <schmiddy@gmail.com>,
	pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: allowing multiple PQclear() calls
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	<CA+U5nML4jNyCGMfXZJ94p7NBxQkVsVL+LrWeS26dd1rVNboPxQ@mail.gmail.com>
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On 02.01.2013 17:27, Marko Kreen wrote:
> On Wed, Jan 2, 2013 at 5:11 PM, Boszormenyi Zoltan<zb@cybertec.at>  wrote:
>> 2012-12-11 16:09 keltez=E9ssel, Simon Riggs =EDrta:
>>
>>> On 11 December 2012 12:18, Boszormenyi Zoltan<zb@cybertec.at>  wrote:
>>>
>>>>>> 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 versio=
ns?
>>>
>>> No, but we should introduce a new public API call that is safer,
>>> otherwise we get people continually re-inventing new private APIs that
>>> Do the Right Thing, as the two other respondents have shown.
>>>
>>
>> How about these macros?
>
> * Use do { } while (0) around the macros to get proper statement behaviou=
r.
> * The if() is not needed, both PQclear and PQfinish do it internally.
> * Docs
>
> Should the names show somehow that they are macros?
> Or is it enough that it's mentioned in documentation?

IMHO this doesn't belong into libpq, the interface is fine as it is.=20
It's the caller's responsibility to set the pointer to NULL after=20
PQclear(), same as it's the caller's responsibility to set a pointer to=20
NULL after calling free(), or to set the fd variable to -1 after calling=20
close(fd). There's plenty of precedence for this pattern, and it=20
shouldn't surprise any programmer.

- Heikki


--=20
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