Re: [PATCH/RFC] parse-options.c: make OPTION__COUNTUP consider negative values

[Pranit Bauva <pranit.bauva@gmail.com>]

On Sun, Mar 20, 2016 at 9:40 AM, Jeff King <peff@peff.net> wrote:
>> > We are also changing semantics without changing the interface, which
>> > means any topics in flight (that you _cannot_ review, because you have
>> > not seen them yet) may be subtly broken. To me that is not an absolute
>> > deal-breaker, but something to weigh against the utility of the change.
>>
>> As I am new here, I don't really know how to go about with this. Could
>> you describe in a little detail so that I can work on it?
>
> A more canonical example is changing a function return value. Imagine I
> have a function which returns "1" for success and "0" for error, and I
> want to change it to return "0" for success and "-1" for error. If I do
> so and update each caller, then merging with a branch that has a new
> caller will not result in any conflicts (there is no textual link
> between the callers and the function), but the result will be subtly
> broken (the new caller will get the error-check wrong).
>
> So we generally try to find some way that the compiler will notice the
> breakage. E.g., if the function changes name when the return value
> semantics change, or if it gains a new argument at the same time, then
> the compiler will notice and complain. We still have to fix it up during
> the merge, of course, but it's easy to spot.
>
> Likewise here. If you change the semantics of OPT_COUNTUP(), then any
> branch which introduces a new use of "int foo = -1" and expects the old
> semantics will be subtly broken.
>
> The obvious fix would be to switch the name (to OPT_COUNTUP_DEFAULT() or
> something). But that's a bit painful, as almost nobody uses COUNTUP
> directly, so we'd need OPT__VERBOSE_DEFAULT().

This is quite new to me. It took me some time to digest it.

> Which in the end is the same as ignoring the problem in the first place,
> but there is a big difference between not thinking about the problem,
> and thinking about it and deciding it's not a problem. :)
True That! ;)

Regards,
Pranit Bauva