Re: json/jsonb/hstore operator precedence

From: Jim Nasby <jim(at)nasby(dot)net>
To: Andrew Dunstan <andrew(at)dunslane(dot)net>
Cc: Greg Stark <stark(at)mit(dot)edu>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: json/jsonb/hstore operator precedence
Date: 2014-04-01 21:42:18
Message-ID: 533B32BA.7060303@nasby.net
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On 4/1/14, 3:07 PM, Andrew Dunstan wrote:
>> What are cases where things would break if we changed the precedence of -> and ->>? ISTM that's what we really should do if there's some way to manage the backwards compatibility...
>
>
> There is no provision for setting the precedence of any operators. The precedence is set in the grammar, and these all have the same precedence. What you're suggesting would a cure far worse than the disease, I strongly suspect. You just need to learn to live with this.
>
> What really bugs me about the example is that <> has a different precedence from =, which seems more than odd. The example works just fine if you use = instead of <>. But I guess it's been that way for a very long time and there's not much to be done about it.

I'm confused... first you say there's no precedence and then you're saying that there is? Which is it?

ISTM that most languages set the priority of de-referencing operators to be quite high, so I don't see how that would be a disaster?

Of course, changing the precedence of = and <> certainly would be a disaster; I'm not suggesting that.
--
Jim C. Nasby, Data Architect jim(at)nasby(dot)net
512.569.9461 (cell) http://jim.nasby.net

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