| From: | Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> | 
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> | 
| Cc: | Daniel Verite <daniel(at)manitou-mail(dot)org>, PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org> | 
| Subject: | Re: Variable substitution in psql backtick expansion | 
| Date: | 2017-04-03 19:24:39 | 
| Message-ID: | alpine.DEB.2.20.1704032118250.23892@lancre | 
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| Lists: | pgsql-hackers | 
Hello Tom,
>>   \if [select current_setting('server_version_num')::int < 110000]
>
> I really dislike this syntax proposal.
> It would get us into having to count nested brackets, and distinguish 
> quoted from unquoted brackets, and so on ... and for what?  It's not 
> really better than
>
>   \if sql select 1 from pg_catalog.pg_extension where extname='pgcrypto'
Hmmm. On the positive side, it looks more expression-like, and it allows 
to think of handling a multi-line expression on day.
ISTM that the lexer already counts parentheses, so maybe using external 
parentheses might work without much effort?
> (ie, "\if sql ...text to send to server...").
>
> If you're worried about shaving keystrokes, make the "select" be implicit.
> That would be particularly convenient for the common case where you're
> just trying to evaluate a boolean expression with no table reference.
I'm looking for a solution to avoid the suggested "sql" prefix, because "I 
really dislike this proposal", as you put it.
-- 
Fabien.
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