From: L J Bayuk <ljb220@mindspring.com>
Message-Id: <200401190238.i0J2cUwB000262@mindspring.com>
Subject: Re: PQsetNoticeReceiver issues
To: peter_e@gmx.net (Peter Eisentraut)
Date: Sun, 18 Jan 2004 21:38:30 -0500 (EST)
Cc: jgardner@jonathangardner.net (Jonathan Gardner),
	pgsql-interfaces@postgresql.org
In-Reply-To: <200401181119.58577.peter_e@gmx.net> from "Peter Eisentraut" at
	Jan 18, 2004 11:19:58 AM
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Peter Eisentraut wrote:
> 
> Jonathan Gardner wrote:
> > I've run into a conundrum with the PQsetNoticeReceiver function call.
> > How do you set it back to the original default? How do you call the
> > appropriate PQnoticeProcessor as well?
> 
> The documentation says:
> 
>  Each of these functions returns the previous notice receiver or 
> processor function pointer, and sets the new value. If you supply a 
> null function pointer, no action is taken, but the current pointer is 
> returned.

Saving and restoring the previous noticeProcessor or noticeReceiver handler
function works, unless they actually made use of the "arg" pass-through
argument.  For example, somewhere you have:
     PQsetNoticeProcessor(conn, myNoticeProc, &mydata);

And somewhere else you want to temporarily override the noticeProcessor:
     prevNoticeProc = PQsetNoticeProcessor(conn, newNoticeProc, &newdata);
     /* ... Do something which makes a notice ... */

     /* Restore previous notice processor */
     PQsetNoticeProcessor(conn, prevNoticeProc, ????);
     /* Oops, lost the previous "arg". */
Not exactly a huge API hole, but nevertheless...