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From: Andrew Chernow <ac@esilo.com>
To: Merlin Moncure <mmoncure@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andrew Dunstan <andrew@dunslane.net>
Cc: Alvaro Herrera <alvherre@commandprompt.com>
Cc: Patches (PostgreSQL) <pgsql-patches@postgresql.org>
Subject: Re: libpq object hooks
Date: Wed, 14 May 2008 12:34:08 -0400
Message-ID: <482B1480.1070705@esilo.com> (raw)
In-Reply-To: <b42b73150805140921v30d24b75m6c230932c61ffdd2@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>
	<b42b73150805140921v30d24b75m6c230932c61ffdd2@mail.gmail.com>

Merlin Moncure wrote:
> On Wed, May 14, 2008 at 10:44 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I'm wondering why the hooks need names at all.  AFAICS all that
>> libpq needs to know about a hook is a callback function address
>> and a void * passthrough pointer.
> 
> For reference...here is what libpqtypes has to do to bind via the
> hooking interface:
> http://libpqtypes.esilo.com/browse_source.html?file=hooks.c
> 
> Are you proposing something substantially different (not my handle
> suggestion)? How would it work exactly?
> 
> merlin
> 
> 

It is important to see how "NON-hook-callback" functions in libpqtypes 
make use of the hook data.

PQparamCreate must get a pointer to the conn hook data
http://libpqtypes.esilo.com/browse_source.html?file=param.c#line24

PQgetf must get a pointer to the result hook data
http://libpqtypes.esilo.com/browse_source.html?file=exec.c#line65

These are NOT hook callbacks.  The hook data is NOT isolated to callback 
functions.  It is memory that is publically accessible, outside hook 
implementations.

-- 
Andrew Chernow
eSilo, LLC
every bit counts
http://www.esilo.com/



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