Re: [PATCH v11 2/4] parse-options.c: make OPTION_COUNTUP respect "unspecified" values

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 31, 2016, 20:06 UTC
Message-ID: <xmqqegaqmmyr.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <CAFZEwPO4CJ-Q=52Es14CdD0mjG-qgy4=X2kU71npi=8x7FsSQw@mail.gmail.com>

Pranit Bauva <pranit.bauva@gmail.com> writes:

Show 16 quoted lines

> On Fri, Apr 1, 2016 at 12:11 AM, Junio C Hamano <gitster@pobox.com> wrote:
>>
>>         case OPTION_COUNTUP:
>> +               if (*(int *)opt->value < 0)
>> +                       *(int *)opt->value = 0;
>>                 *(int *)opt->value = unset ? 0 : *(int *)opt->value + 1;
>>
>> That is, upon hitting this case arm, we know that an explicit option
>> was given from the command line, so the "unspecified" initial value,
>> if it is still there, gets reset to 0, and after doing that, we just
>> do the usual thing.
>
> This does look cleaner. Nice thinking that there is no need to
> actually specify when it gets 0. It gets 0 no matter what as long as
> OPTION_COUNTUP is speficied in any format (with or without --no) and
> variable is "unspecified".

I do not think there is any planned users of such an enhancement, but the above points us into a future possibility to be able to do this:

        case OPTION_COUNTUP:
+               if (*(int *)opt->value < 0)
+                       *(int *)opt->value = -*(int *)opt->value - 1;
                *(int *)opt->value = unset ? 0 : *(int *)opt->value + 1;

That is, by using "-2" as the "unspecified" value, you can start counting up from 2 (i.e. the presence of the option resets the variable to 1 and then the option being not "unset" increments it) if your application wants to.