Re: [PATCH 2/3] xdiff: -W: include immediately preceding non-empty lines in context

From: Junio C Hamano <gitster@pobox.com>
Date: Jan 15, 2017, 02:39 UTC
Message-ID: <xmqqy3ydcaia.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <48bdfd94-2fd4-bd55-d78b-2877e195fb82@web.de>

René Scharfe <l.s.r@web.de> writes:

Show 15 quoted lines

>> I am also more focused on keeping the codebase maintainable in good
>> health by making sure that we made an effort to find a solution that
>> is general-enough before solving a single specific problem you have
>> today.  We may end up deciding that a blank-line heuristics gives us
>> good enough tradeoff, but I do not want us to make a decision before
>> thinking.
>
> How about extending the context upward only up to and excluding a line
> that is either empty *or* a function line?  That would limit the extra
> context to a single function in the worst case.
>
> Reducing context at the bottom with the aim to remove comments for the
> next section is more tricky as it could remove part of the function
> that we'd like to show if we get the boundary wrong.  How bad would it
> be to keep the southern border unchanged?

I personally do not think there is any robust heuristic other than Vegard's "a blank line may be a signal enough that lines before that are not part of the beginning of the function", and I think your "hence we look for a blank line but if there is a line that matches the function header, stop there as we know we came too far back" will be a good-enough safety measure.

I also agree with you that we probably do not want to futz with the southern border.

Thanks.