Now that we auto-evolve after most operations, the user may not know
what "evolve" means. Even before that, the way `jj evolve` resolved
orphans after pruning was by rebasing them.
The project is starting to work well enough that I think it's time
that the documentation targets users instead of VCS hackers. This
patch rewrites much of the README to describe how the features help
the user instead of describing how they work. It also adds a tutorial.
Perhaps it makes more sense to display the working copy commit just
above the changes in the working copy commit, even though that means
that the order between the working copy commit and the parent becomes
the opposite of the order in `jj log`.
I had initially hoped that the type-safety provided by the separate
`FileRepoPath` and `DirRepoPath` types would help prevent bugs. I'm
not sure if it has prevented any bugs so far. It has turned out that
there are more cases than I had hoped where it's unknown whether a
path is for a directory or a file. One such example is for the path of
a conflict. Since it can be conflict between a directory and a file,
it doesn't make sense to use either. Instead we end up with quite a
bit of conversion between the types. I feel like they are not worth
the extra complexity. This patch therefore starts simplifying it by
replacing uses of `FileRepoPath` by `RepoPath`. `DirRepoPath` is a
little more complicated because its string form ends with a '/'. I'll
address that in separate patches.
I thought I had looked for this case and cleaned up all the places
when I made `Transaction::commit()` return a new `ReadonlyRepo`. I
must have forgotten to do that, because there we tons of places to
clean up left.
If you ran two concurrent `jj describe` (for example) before this
patch, they'd both try to open an editor on the same file. This patch
fixes that by randomizing the filename. It also deletes the file at
the end so the `.jj/` directory is not cluttered by these files.
It's annoying to have to run run `jj evolve`, and it's easy to forget
(especially after updating the description of the working copy
parent), so let's just always do it. Unlike most VCSs, we don't have
to worry about merge conflicts since we can represent them in commits.
This commit rewites the divergence-resolution part of `evolve()` as an
iterator (though not implementing the `Iterator` trait). Iterators are
just much easier to work with: they can easily be stopped, and errors
are easy to propagate. This patch therefore lets us propagate errors
from writing to stdout (typically pipe errors).
