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Re: HEAD \df doesn't show functions with no arguments

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: Michael Fuhr <mike(at)fuhr(dot)org>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: HEAD \df doesn't show functions with no arguments
Date: 2005-04-01 05:26:20
Message-ID: 3264.1112333180@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> Tom Lane wrote:
>> What makes you think you can't call 'em from SQL?

> Yes, I guess I mean does it make sense to call them from SQL?  Their
> purpose is for internal use, no?

People have actually used them for purposes of cross-type conversion
where there's I/O compatibility but no built-in cast.  For instance
you can't
	regression=# select '(1,2)'::point::text;
	ERROR:  cannot cast type point to text
but you can
	regression=# select textin(point_out('(1,2)'::point));
	 textin 
	--------
	 (1,2)
	(1 row)
Before you look down your nose at that, consider it's *exactly* what
plpgsql does whenever it needs to do a type conversion.

I think this decision was taken many years ago when indeed you couldn't
use the things from SQL, but it's an obsolete point of view.  It's not
like the functions are typically named in a way that conflicts with
other functions.  If I do "\df int4in", what exactly do you think I'm
looking for, and why should psql not show it to me?

			regards, tom lane

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