Re: [PATCH v2 2/2] blame: allow blame --reverse --first-parent when it makes sense

From: Junio C Hamano <gitster@pobox.com>
Date: Oct 25, 2015, 16:52 UTC
Message-ID: <xmqqk2qalwka.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <20151025124338.GA27615@wheezy.local>

Max Kirillov <max@max630.net> writes:

> This additionally forbids having several end commits
> (git blame --reverse --first-parent ^A B C ...), but
> this does not seem to have much practical use.

Even if there were practical uses for a request with multiple end points, a solution that

 (1) guarantees that "blame --reverse --first-parent" is the only
     thing that is affected; and

 (2) errors out if "blame --reverse --first-parent" cannot give a
     sensible answer.

is a strict improvement over "we don't know how to produce a sensible answer in all cases, so we just forbid". Somebody who needs multiple end points badly can build on top with the same principle, just widening the definition of what is "a sensible answer" in the criteria (2) above. Until then, defining the sensible answer to be "an answer that consists of commits on the first parent chain (but in reverse)" is perfectly fine [*1*].

As you added your patch after "-- <EOL>", my MUA refuses to quote it in this response, but that's OK, as this message is not about the patch itself ;-)

[Footnote]

*1* I haven't read the patch text to see if that is what the updated
    code is computing, though.  That's for a weekday ;-).