[RFI] Annotations cache & progressive display of annotations

[Stefan Monnier]

> It's a bit interesting to consider how this would happen in Emacs but
> you could possibly emit a text stream of linenumber:origin_details
> that emacs could reassemble.

That could work, indeed.  Thanks for thinking of the Emacs case.

BTE, while we're on the subject, I'd like to push yet again for the
introduction of a different feature that could be used instead of
"annotate": a "bzr log --diffs --lines NN..MM FILE" which would show the
log history not of a complete file, but only of a particular region of
that file (and show the diffs alongside the log-messages).

Usually, when I use "annotate" it is really just a way to manually build
the above log.  More specifically I always end up doing:
1- annotate
2- find the revision number for the lines of interest
3- get the log and diff of that revision
4- if the problem comes from the code before that patch (because the patch
   just reindents or performs some unrelated change), go back to (1)
   applied to the earlier revision.

This clearly could be created incrementally going backward in time, just
like any other "bzr log" and would be more useful to me than `annotate'.
I'd even settle for (or maybe prefer) a command that only does one step
of the above loop.  I could even code it up in Emacs if Bzr could
provide some way to get the revision number of a particular line (or
set of lines).


        Stefan