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

Revised patch, with one caveat: It contains copy/pasted code from
variable.c intended to bridge the gap until https://commitfest.postgresql.
org/12/799/ (changing ParseVariableBool to detect invalid boolean-ish
strings) is merged. We may want to pause full-review of this patch pending
resolution of that one. I'm happy to continue with the stop-gap in place.

Changes made:
- \elseif is now \elif
- Invalid boolean values now return an error
- ON_ERROR_STOP is respected in all errors raided by \if, \elsif, \else,
\endif commands.
- Documentation gives a more real-world example of usage.
- Documentation gives a more explicit list of valid boolean values
- Regression tests for out-of-place \endif, \else, and \endif
- Regression test for invalid boolean values
- Removal of debug detritus.

Changes not(yet) made:
- No TAP test for errors respecting ON_ERROR_STOP
- function comments in psqlscan.l follow the style found in other comments
there, which goes counter to global style.

On Tue, Jan 24, 2017 at 3:58 AM, Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> wrote:

>
> I would suggest to assume false on everything else, and/or maybe to ignore
>>> the whole if/endif section in such cases.
>>>
>>
>> +1, it also halves the number of values we have to support later.
>>
>
> After giving it some thought, I revise a little bit my opinion:
>
>
> I think that if the value is evaluated to TRUE or FALSE, then fine. If it
> is anything else, then an error is raised (error message shown), which
> should also stop the script on "ON_ERROR_STOP", and if not the script
> continues with assuming the value was FALSE.
>
> --
> Fabien.
>