Re: Specifying N revisions after the initial commit

From: Josh Boyer <jwboyer@gmail.com>
Date: Sep 22, 2015, 20:11 UTC
Message-ID: <CA+5PVA6zUXGs2R-MOoj5sBxwUqM7HP=tx-0WZJzPf71MsjH9MA@mail.gmail.com>
In-Reply-To: <xmqqpp1a2pql.fsf@gitster.mtv.corp.google.com>

On Tue, Sep 22, 2015 at 3:55 PM, Junio C Hamano <gitster@pobox.com> wrote:

Show 15 quoted lines

> Josh Boyer <jwboyer@gmail.com> writes:
>
>> On Tue, Sep 22, 2015 at 2:40 PM, Konstantin Khomoutov
>> ...
>>> Hence, given any particular commit, you're able to trace all of its
>>> ancestry, but the reverse is not possible.
>>
>> That makes sense.  I suppose I will have to resort to parsing output
>> of git-rev-list or something.  Thanks for the reminder.
>
> I think Konstantin explained why it fundamentally does not make
> sense to ask "which one is the Nth one after the root".  I am not
> sure how running rev-list and count its output would help, unless
> you are now solving a different problem (perhaps "find all the ones
> that are Nth after some root", which does have an answer).

Oh, context would help, yes. In the case of the tree I'm parsing, I know for a fact that the commit history is entirely linear and will (should) always remain so. E.g.

A - B - C - D - E - F ... {N}

So yes, finding e.g. the second commit after the root is complicated for something resembling anything like a typical git repo, but this isn't like that. In other words, I can cheat. Or at least I'm pretty sure I can cheat :).

josh