Re: [PATCH v2 8/8] tests: disallow the use of abbreviated options (by default)

[Junio C Hamano <gitster@pobox.com>]

Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:

> Hi Junio,
>
> On Mon, 15 Apr 2019, Junio C Hamano wrote:
>
>> Junio C Hamano <gitster@pobox.com> writes:
>>
>>
>> > Do you mean more like
>> > ...
>> > I think I can agree with either of the two positions...
>>
>> I am guessing from the earlier iteration that you wanted to say
>> "unless it is given explicitly, we turn it on".
>>
>> As this last-minute style update that was botched, and a typofix in
>> the proposed log message in 8/8, are the only differences, let me
>> locally fix 8/8 up and replace it.
>
> Sure. I still would like the `isset` thing, as it makes things more
> consistent, but I'll not fight for it.

${var:+isset} is fine.  Instead of

+# Disallow the use of abbreviated options in the test suite by default
+if test -z "${GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS}"
+then
+	GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS=true
+	export GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS
+fi
+

if you used

	if test -z "${GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS:+isset}"
	then
		...

I won't object.  After all, I know I introduced :+isset pattern to
our shell script codebase as there are cases where it makes the
result easier to follow.

But the thing is that your patch had the polarity inverted.  Where
you must say "if this thing is not set, assign this value", you said
"if this thing is set, assign this value", which was totally bogus.
As long as that is corrected, that's fine.

Having said that.

When you check if the variable is set, use of the ":+isset" pattern
makes the result often easier to follow by explicitly letting us
compare with an explicit "isset" token, e.g.

	case ",${VAR1:+isset},${VAR2:+isset}," in
	*,isset,*)	: at least one is set ;;
	*)		: neither is set ;;
	esac

This *does* make the code simpler and easier.  But when checking for
"is it not set?", you can compare with an explicit literal "" and
that comparison is plenty clear enough.  You won't get as much
benefit as the "is it set?" test would out of the pattern.  I would
not say that it is pointless to use the ":+isset" pattern when
checking "is it not set?", but it is very close.