Date: Wed, 1 Sep 2004 07:33:29 -0700 (PDT)
From: Stephan Szabo <sszabo@megazone.bigpanda.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Peter Eisentraut <peter_e@gmx.net>, sad <sad@bankir.ru>,
	Michael Glaesemann <grzm@myrealbox.com>, pgsql-sql@postgresql.org
Subject: Re: casting BOOL to somthng 
In-Reply-To: <6204.1094048394@sss.pgh.pa.us>
Message-ID: <20040901072051.N70341@megazone.bigpanda.com>
References: <200408311306.25545.sad@bankir.ru>
	<8AF2CE57-FBE1-11D8-A2A0-000A95C88220@myrealbox.com>
	<200409010955.45834.sad@bankir.ru> <200409010859.08037.peter_e@gmx.net>
	<6204.1094048394@sss.pgh.pa.us>
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On Wed, 1 Sep 2004, Tom Lane wrote:

> Peter Eisentraut <peter_e@gmx.net> writes:
> > The cast to text, however, is part of the data model, and it has to be
> > both natural and universal.  I think you agree that there is no
> > universal, obvious correspondence between character strings and boolean
> > values, at least not nearly as universal and obvious as the well-known
> > correspondence between character strings and numbers.  We could pick
> > one arbitrary correspondence and implement it, and if we did we would
> > probably pick one that is consistent with the mapping used by libpq and
> > other frontends.  But doing that gains no functionality, so why bother?
>
> Actually it does gain functionality, because there are plenty of times
> when you need to manipulate a textual representation of a data value.

I don't think that doing so apart from trying to do output representation
is really a good idea in general (and for that I'd think something like
to_char would be more appropriate). For example, if people are casting
macaddrs to text in order to substring them or some such, that implies
to me that there are additional operations on macaddr we should have.