Version Control in Emacs

1. Supported Version Control Systems
2. Current status: C-x v d
3. Diff: C-x v =
4. Ediff: M-x ediff-revision or C-x v M-=
5. Check-in: C-x v v
6. Discard changes: C-x v u
7. Annotate: C-x v g
8. View another revision: C-x v ~
9. Log view
10. Porting code among branches
11. Corresponding code

1 Supported Version Control Systems

All the version control systems I has ever confronted with are supported either with builtin packages or 3rd-party ones. There are more powerful (and more specific) plugins. But I simply prefer the builtin ones since these wrappers adapt interfaces of different VC systems to a uniform Emacs VC interface.

cvs: builtin
svn: builtin
git: builtin
clearcase: I am using vc-clearcase.
perforce: I was using p4.el years before. Now, vc-p4.el seems more appealing to me (but I am no longer using perforce).

In examples in this post, I mainly use git and sometimes cvs. If you are using other VC systems, say SVN, the screen output may differ slightly. But the operations shall be the same.

2 Current status: `C-x v d`

3 Diff: `C-x v =`

C-u C-x v = to speficy versions to diff.

In the diff buffer, "n/p" to navigate, "<enter>" to jump to corresponding line in corresponding file.

4 Ediff: `M-x ediff-revision` or `C-x v M-=`

If you prefer the "fancier" ediff,

5 Check-in: `C-x v v`

To be accurate, this is "vc-next-action".
You can't forget to save files.
M-p to reuse previous log messages.

6 Discard changes: `C-x v u`

This will

Automatically pop up a diff window to help you recollect what as changed.
Ask you for confirmation.

7 Annotate: `C-x v g`

Also note the indication of branch in mode line.

8 View another revision: `C-x v ~`

Or, do it in log view as described later

9 Log view

9.1 Entering the log view: `C-x v l` (Or `l` in `vc-dir` buffer)

9.2 For a directory, log view shows the topolopy

9.3 Diff a rev with its previous one by pressing `d`

9.4 Diff arbitrary two marked revs (use `m` to mark)

This one and the following one need code snippets attached at the end of this article.

9.5 Other hotkeys in log view buffer

Ediff instead of diff by D
This will be much slower than plain diff if the file is large and the network is slow.
View (retrieve) a revision by f
Annotate revision by a

9.6 Screenshots for cvs

9.6.1 1

9.6.2 2

9.6.3 3

10 Porting code among branches

This is a functionality tailored for my convenience. The code is ugly, but works.

You are in a buffer under CVS.
M-x lgfang-cvs-co
It asks for a TAG. Input one (usually, you just M-p to get one from input history).
It asks for module (file). In most cases, just press "enter".
It asks if you want merge.
It will then
1. create a directory $HOME/sandbox/tag-you-entered/.
2. checkout the file (module) you specified with that tag.
3. merge the change (cvs update -j tag filename).
4. open the file just checked-out.

11 Corresponding code

(eval-after-load "log-view"
  '(progn

     ;; the default face for marked log entries are too hard to spot
     (set-face-attribute 'log-view-file nil :slant
                    'italic :weight 'bold :height 1.1)

     (defun lgfang-log-view-diff (beg end)
       "Overwrite the default log-view-diff, uses log-view-get-marked"
       (interactive
        (if (log-view-get-marked) (log-view-get-marked)
          (list (log-view-current-tag (point))
                (log-view-current-tag (point)))))
       (when (string-equal beg end)
         (save-excursion
           (goto-char (point))               ;not marked
           (log-view-msg-next)
           (setq beg (log-view-current-tag))))
       (vc-version-diff
        (if log-view-per-file-logs
            (list (log-view-current-file))
          log-view-vc-fileset)
        beg end))
     (fset 'log-view-diff 'lgfang-log-view-diff)

     (defun lgfang-log-view-ediff (beg end)
       "Similar to lgfang-log-view-diff, uses ediff and much slower."
       (interactive
        (if (log-view-get-marked) (log-view-get-marked)
          (list (log-view-current-tag (point))
                (log-view-current-tag (point)))))
       (when (string-equal beg end)
         (save-excursion
           (goto-char (point))               ;not marked
           (log-view-msg-next)
           (setq beg (log-view-current-tag))))

       (ediff-load-version-control)
       (funcall (intern (format "ediff-%S-internal" ediff-version-control-package))
                beg end nil))

     (define-key log-view-mode-map (kbd "D") 'lgfang-log-view-ediff)))

(eval-after-load 'vc-hooks
  '(progn
     (defun lgfang-vc-ediff ()
       "Similar to vc-diff, but uses ediff. From network"
       (interactive)
       (require 'ediff)
       (let ((file (or (buffer-file-name)
                       (error "Current buffer is not visiting a file"))))
         (if (and (buffer-modified-p)
                  (y-or-n-p (message "Buffer %s is modified. Save buffer? "
                                     (buffer-name))))
             (save-buffer (current-buffer)))
         (ediff-load-version-control)
         (funcall
          (intern (format "ediff-%S-internal" ediff-version-control-package))
          "" "" nil)))
     (define-key vc-prefix-map (kbd "M-=") 'lgfang-vc-ediff)))

(defvar lgfang-vc-tag-history nil "History list for tags")

(defun lgfang-cvs-co(tag module tomerge)
  (require 'pcvs)
  (interactive
   (list (read-from-minibuffer
          "tag: " nil nil nil 'lgfang-vc-tag-history)
         (read-from-minibuffer
          "module:"
          (replace-regexp-in-string ".*sandbox/[^/]*/" ""
                                    (buffer-file-name))
          nil nil 'minibuffer-history)
         (y-or-n-p "merge ")))
  (let* ((sandbox (file-name-as-directory
                   (expand-file-name "~/sandbox")))
         (directory (concat sandbox
                            (if (string-equal tag "") "main" tag)))
         (working-rev (vc-working-revision (buffer-file-name))))
    (make-directory directory t)
    (cvs-cmd-do "checkout" directory
                (list "-r" tag module) nil 'new :noexist t)
    (when tomerge
      (cvs-cmd-do "update" directory
                  (list "-j" working-rev module) nil 'new :noexist t))
    (find-file (concat directory "/" module))))

Version Control in Emacs

Table of Contents

1 Supported Version Control Systems

2 Current status: C-x v d

3 Diff: C-x v =

4 Ediff: M-x ediff-revision or C-x v M-=

5 Check-in: C-x v v

6 Discard changes: C-x v u

7 Annotate: C-x v g

8 View another revision: C-x v ~