Horton

Re: \if, \elseif, \else, \endif (was Re: PSQL commands: \quit_if, \quit_unless)

Pavel Stehule <pavel.stehule@gmail.com>

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From: Pavel Stehule <pavel.stehule@gmail.com>
To: Fabien COELHO <coelho@cri.ensmp.fr>
Cc: Daniel Verite <daniel@manitou-mail.org>, Tom Lane <tgl@sss.pgh.pa.us>, Corey Huinker <corey.huinker@gmail.com>, Greg Stark <stark@mit.edu>, Erik Rijkers <er@xs4all.nl>, Robert Haas <robertmhaas@gmail.com>, Jim Nasby <Jim.Nasby@bluetreble.com>, PostgreSQL <pgsql-hackers@postgresql.org>, pgsql-hackers-owner@postgresql.org
Date: 2017-02-23T19:55:54Z
Lists: pgsql-hackers 
2017-02-23 18:52 GMT+01:00 Fabien COELHO <coelho@cri.ensmp.fr>:

>
> Hello Daniel,
>
> Ah, I see why *that* wants to know about it ... I think.  I suppose you're
>>> arguing that variable expansion shouldn't be able to insert, say, an
>>> \else
>>> in a non-active branch?  Maybe, but if it can insert an \else in an
>>> active
>>> branch, then why not non-active too?  Seems a bit inconsistent.
>>>
>>
>> Are we sold on the idea that conditionals should be implemented
>> by meta-commands, rather than for example terminal symbols of
>> a new grammar on top of the existing?
>>
>
> I would say that this already exists server-side, and it is named
> PL/pgSQL:-)
>
> I think that once psql has started with \xxx commands, then client-side
> extensions must stick with it till the end of time.


+1

we don't need strong client side scripting language - it should be just
simple.

Pavel

>
>
> --
> Fabien.
>
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Commits

  1. Support \if ... \elif ... \else ... \endif in psql scripting.

  2. Add a "void *" passthrough pointer for psqlscan.l's callback functions.