Re: Itches with the current rev spec

From: Junio C Hamano <gitster@pobox.com>
Date: Apr 30, 2013, 04:02 UTC
Message-ID: <7vip34fyyc.fsf@alter.siamese.dyndns.org>
In-Reply-To: <7vobcxl3ui.fsf@alter.siamese.dyndns.org>

Junio C Hamano <gitster@pobox.com> writes:

Show 11 quoted lines

> A much larger issue is that the current setup_revisions()
> infrastructure does not let us express an operation that involves
> two or more DAGs.  People sometimes wish to say an equivalent of
>
>     git show $(git rev-list A..B) $(git rev-list C..D)
>
> but obviously
>
>     git show A..B C..D
>
> is not the way to say it, and this limitation comes from it.

Just a clarification. Technically, this is _not_ impossible. With some (read: quite a lot of) work to move objects.flags out of the object and to allow unbounded number of flag bits, you could support arbitrary number of ranges that are UNION'ed together by pretty much the same code structure as the current revision machinery. You need 2 x N bits (for the above example, 2 x 2 bits) per commit.

I am not saying it is easy or we should start working on it, though ;-).