• CategoryEmacs

Emacs modes for darcs

• http://fresh.homeunix.net/~luke/misc/darcs-mode/ - a non-VC darcs mode, simple and handy

• http://sacha.free.net.ph/notebook/emacs/pcmpl-darcs.el - Programmable completion for darcs commands in the Emacs shell

• http://www.emacswiki.org/cgi-bin/wiki/VcDarcs - vc-darcs.el, a Darcs backend for VC

• http://www.pps.jussieu.fr/~jch/software/repos/vc-darcs/ - JuliuszChroboczek's version of vc-darcs.el, which works with recent Darcs versions, allows browsing of older revisions, and cooperates with Tramp.

• DarcsMode - Collecting ideas for a new darcs mode

• DarcsumMode - darcs summary mode by John Wiegley and Christian Neukirchen. This is does not use vc, but provides an unrecorded changes browser that fits in better with darcs. It's very useful but needs help - it sometimes fails and leaves long-running darcs processes with large repos.

Use Emacs as an external merge tool for darcs

(There's a more comprehensive example in the manual for darcs 1.0.5.)

Create the following wrapper script:

#!/bin/sh
#
# 3 way merge using emacs from the command line

emacs --eval="(ediff-merge-files-with-ancestor \"$1\" \"$2\" \"$3\" nil \"$4\")"

then invoke darcs pull as follows:

$ darcs pull --external-merge='/path/to/the/wrapper/script.sh %1 %2 %a %o'

or just put the following line into ~/.darcs/defaults:

ALL external-merge /path/to/the/wrapper/script.sh %1 %2 %a %o

Protect against accidentally editing files in _darcs/current

More than once I found myself making an edit in the _darcs/current copy of a file; probably due to an accident with find-dired. This pops up a warning in that case and will optionally open the normal version of the file.

Add the following to your .emacs:

(add-hook 'find-file-hooks 'warn-if-darcs-file)
(defun warn-if-darcs-file()
  (let ((f (buffer-file-name (current-buffer))))
    (and f (string-match "_darcs" f)
         (if (y-or-n-p "This is a _darcs file, open the real file? ")
             (jump-to-real-file-from-darcs)
           (push '(:propertize "_DARCS-FILE:" face font-lock-warning-face)
                 mode-line-buffer-identification)))))
(defun jump-to-real-file-from-darcs()
  (interactive)
  (let* ((f (buffer-file-name (current-buffer)))
         (match (string-match "_darcs/current" f)))
    (and f match
         (find-alternate-file
          (concat (substring f 0 (match-beginning 0))
                  (substring f (match-end 0)))))))

I have included some code inspired by his in vc-darcs.el; I'd like to credit the original author, please drop me a line. -- JCh

The above code is a nuisance when using darcsum-ediff. Also, the warning label is lost at the end of the ediff. I prefer it as follows. -- trb

; prevent accidental editing of files in darcs repository
(add-hook 'find-file-hooks 'label-darcs-file-with-warning)
;; warn against accidental writing to a _darcs file
(add-hook 'write-file-hooks 'warn-writing-darcs-file)
; affix a warning label to any _darcs file buffer
(defun label-darcs-file-with-warning()
  (let ((f (buffer-file-name (current-buffer))))
    (and f (string-match "_darcs" f)
         (rename-buffer (concat "_DARCS-FILE:" (buffer-name)) t))))
; prevent accidental writing of files in darcs repository
(defun warn-writing-darcs-file()
  (let ((f (buffer-file-name (current-buffer))))
    (and f (string-match "_darcs" f)
         (if (not (y-or-n-p "WARNING: YOU ARE ABOUT TO WRITE TO an _darcs file, are you sure you want to do this? "))
           (keyboard-quit)))))

There is a general facility for preventing unintentional writes at http://www.loveshack.ukfsn.org/emacs/protect-files.el.

Wishlists

People have created wishlists of what an "ideal" darcs mode for emacs would require.

• http://chneukirchen.org/repos/darcsum/perfect-darcs-mode.txt (Christian Neukirchen; check out this repo for an updated version of darcsum.el)

• Why not use DVC? Darcs will become a backend to the emacs Distributed Version Control mode (http://wiki.gnuarch.org/xtla#DVC)

  • DVC people begin the darcs backend: https://mail.gna.org/public/xtla-el-dev/2006-03/msg00087.html

• I'm thinking the same. Yesterday found out about DVC and saw at http://download.gna.org/dvc/ that darcs back-end is not advancing nicely. Maybe the effort could be directed towards DVC back-end. It would be nice having common DVC interface for people that have to work with several distributed rcs. However, I'm not (yet) familiar with darcsum.el so cannot judge/compare its interface with DVC.