On Fri, 9 Apr 2010, Aghiles wrote:
>
> Oh, I should have read the documentation. I was certain that ".." stands
> for a range but it is a ... complement.
Well, technically ".." means two different things
- for "set operations" (ie "git log" and friends) it's the "relative
complement" of two sets (or "'reachable from A' \ 'reachable from B'").
- for "edge operations" (ie "git diff" and friends) it's just two
end-points (aka "range"). A diff doesn't work on sets, it only works on
the two endpoints.
It's arguably a bit confusing, but quite frankly, the room for confusion
is very small, and the biggest source of confusion is probably not so much
that ".." means two different things in two (clearly different) contexts,
as much as just the fact that people aren't used to thinking in terms of
set operations at all.
Most SCM's really talk about "ranges". Once you think in those terms,
complex history doesn't work. Git very fundamentally is much about set
theory, and "ranges" is a bad word to use.
To make things even more exciting triple-dot, "A...B" has two different
meanings too, again one that is about sets ("symmetric difference") for
the log-based ones, and one that is a somewhat badly defined range for the
diff based ones (where the end-points are "one common nearest ancestor of
A and B" and "B" respectively).
It's all actually very natural when you get used to it, although that
"A...B" as a range really isn't well-defined, since there can be more than
one common nearest ancestors. It's still often enough useful in practice
that I wouldn't get rid of it, but it's not the greatest feature.
Linus
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