From: Tom Lane <tgl@sss.pgh.pa.us>
To: Merlin Moncure <mmoncure@gmail.com>
Cc: Andrew Dunstan <andrew@dunslane.net>
Cc: Alvaro Herrera <alvherre@commandprompt.com>
Cc: Patches (PostgreSQL) <pgsql-patches@postgresql.org>
Cc: Andrew Chernow <ac@esilo.com>
Subject: Re: libpq object hooks
Date: Thu, 15 May 2008 12:09:31 -0400
Message-ID: <6044.1210867771@sss.pgh.pa.us> (raw)
In-Reply-To: <b42b73150805150852m7b3c28fai2d7a4497c84118b2@mail.gmail.com>
References: <b42b73150804301323i18b00019i62e765708abb65aa@mail.gmail.com>
<482A58D8.2030205@dunslane.net>
<20080514043313.GS6966@alvh.no-ip.org>
<482AD896.4000504@dunslane.net>
<19342.1210776271@sss.pgh.pa.us>
<b42b73150805150852m7b3c28fai2d7a4497c84118b2@mail.gmail.com>
"Merlin Moncure" <mmoncure@gmail.com> writes:
> The problem is the functions PQhookData(conn, hookname) and
> PQresultHookData(result, hookName). We need these to work in
> functions that are not callbacks. If we eliminate hookname
> completely, there is no way for libpq to know which private state we
> are asking for.
Well, depending on a hook name for this is broken-by-design anyway,
because there is no way for two independently written libraries to
be sure they don't choose conflicting hook names. So the need for
a hook name has to go away.
It might work to use the address of the hook callback function as
a key for retrieving the associated void * pointer. You'd need to
not register the same callback function more than once per object,
but from what I gather here you don't need to.
regards, tom lane
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To: pgsql-patches@postgresql.org
Cc: tgl@sss.pgh.pa.us, mmoncure@gmail.com, andrew@dunslane.net, alvherre@commandprompt.com, ac@esilo.com
Subject: Re: libpq object hooks
In-Reply-To: <6044.1210867771@sss.pgh.pa.us>
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