Re: PSQL commands: \quit_if, \quit_unless

On Mon, Nov 28, 2016 at 2:03 PM, Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> wrote:

>
> Hello Corey,
>
> This patch adds two very simple psql commands: \quit_if and \quit_unless.
>>
>
> A few comments about the feature design:
>
> I'm unsure about the name, esp with '_'. There are some \lo_* commands,
> but others rely on pasted words (\crosstabview, \errverbose, ...).
>

I'm completely flexible with regard to the names.

> I'm wondering if an simplistic interpreted \if \elsif/\else \fi would make
> more sense:
>

The problem is that \if \elsif \else \fi is anything but simplistic, and
would be a vastly bigger change. Detecting nested if-thens, detecting
un-matched if-thens, etc.

> Quitting seems a little bit definitive, and means that if I have some
> alternatives then I have to have something that relaunch another script
> outside...
>

> When \includes are process, does \quit stop the include or the full
> script. I'm afraid it is the script.
>

It behaves exactly as if the script contained \quit at that location.

> Now probably an \if... would have also some drawbacks, but ISTM that there
> could be less of them.
>

It'd be nice, but I'm trying to keep things simple.

>
> There is no test provided with the patch.

Indeed, but testing such a feature is hard within our current test harness.
I welcome suggestions for how to convert the example script in my first
email to tests.