Re: Precedence of standard comparison operators

From: Kevin Grittner <kgrittn(at)ymail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "pgsql-hackers(at)postgreSQL(dot)org" <pgsql-hackers(at)postgreSQL(dot)org>
Subject: Re: Precedence of standard comparison operators
Date: 2015-02-20 17:18:21
Message-ID: 1142583258.2899141.1424452701561.JavaMail.yahoo@mail.yahoo.com
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Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> One of the reasons I want to make these operators %nonassoc is
> so you get an error on cases like these --- if you actually meant
> this, you'll be forced to parenthesize one way or the other.

I could live with that versus a configurable warning. It's simpler
and makes it less likely that someone will accidentally get
incorrect results without realizing it. If we confirm that the
standard specifies a left-to-right evaluation (which I seem to
recall, but wouldn't trust that memory without confirmation), we
could consider loosening it up five or ten years down the road,
once everyone has code that works with this stricter
implementation.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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