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    1. Make Emacs write (part of) your git commit messages

      I was fed up with the chores of writing consistent git commit messages, so a while ago I started developing a hook in Emacs which I used with Magit (actually git-commit-mode) which uses some crude...

      I was fed up with the chores of writing consistent git commit messages, so a while ago I started developing a hook in Emacs which I used with Magit (actually git-commit-mode) which uses some crude heuristics to fill out the COMMIT_EDITMSG buffer for me. Here is what it does (| stands for the cursor):

      • If only a single file modified, insert <filename>: |

        • If can figure out function name, insert <filename> (<functionname>): |
      • If only a single file added, insert Add <filename>|

      • If a TODO added to Readme.org, insert ; TODO <headline>|

      • If a TODO was DONE, insert ; DONE <headline>|

      • If the files are Readme.org and Readme.org_archive, and no new TODO's were added anywhere, insert ; Archive DONE|

      • If the file is .gitignore, insert ; Ignore |

      • If the file is TAGS, insert ; Update TAGS|

      I extend this when I find new cases where I repeatedly do the same thing. The code is below. It's probably a good idea to use it as a starting point and personalise it because this reflects how I like to write my commit messages (and I like pretending how they do it over at Emacs git repo). It is sloppy and probably buggy, but I don't think it can be destructive.

      Final note: I can't figure out how to set this up so that after this takes effect, the buffer is marked as modified. I want to flip the modified bit so that in some cases I can just hit C-c C-c and go. But I need to modify the buffer somehow to commit in some cases (I just type C-o to open a new line in those cases). Here is the function:

      (defun gk-git-commit-mode-hook ()
        "Set up git commit buffer."
        ;; If a single file is modified, prefix the message w/ it.
        (let ((modified-re "^#	modified:")
              (new-re "^#	new file:")
              (issue-re "^[+\\- ]\\*+ \\(TODO\\|DONE\\) ")
              current-defun filename addp onlyp issuep)
          (save-excursion
            (with-current-buffer "COMMIT_EDITMSG"
              (goto-char (point-min))
              (re-search-forward "^# Changes to be committed:" nil t)
              (forward-line)
              (beginning-of-line)
              (cond ((looking-at modified-re)
                     (re-search-forward ":   " nil t)
                     (setf filename (thing-at-point 'filename t)))
                    ((looking-at new-re)
                     (re-search-forward ":   " nil t)
                     (setf filename (thing-at-point 'filename t)
                           addp t)))
              (setq onlyp (progn
                            (forward-line)
                            (not (or (looking-at modified-re)
                                     (looking-at new-re)))))
              (when (and onlyp (equal filename "Readme.org"))
                (goto-char (point-min))
                (when-let* ((pos (re-search-forward issue-re nil t)))
                  (setq issuep (progn
                                 (re-search-backward "\\*" nil t)
                                 (buffer-substring (1+ (point))
                                                   (line-end-position))))))
              ;; Try to set ‘current-defun’.
              (when onlyp
                (save-excursion
                  (goto-char (point-min))
                  ;; Error if not found, means verbose diffs
                  ;; not enabled.
                  (re-search-forward "^diff --git")
                  (goto-char (line-beginning-position))
                  (let ((str (buffer-substring (point) (point-max)))
                        (default-directory (expand-file-name "..")))
                    (with-temp-buffer
                      (insert str)
                      (diff-mode)
                      (goto-char (point-min))
                      (setq current-defun (diff-current-defun))))))))
          (if onlyp
              (cond
               ((and issuep (not addp))
                (goto-char (point-min))
                (insert ";" issuep))
               ((equal filename "TAGS")
                (goto-char (point-min))
                (insert "; Update TAGS"))
               ((equal filename ".gitignore")
                (goto-char (point-min))
                (insert "; Ignore "))
               (filename
                (goto-char (point-min))
                (if addp
                    (insert "Add " filename)
                  (insert
                   filename
                   (if (and current-defun)
                       (format " (%s)" current-defun)
                     "")
                   ": "))))
            (when (and (equal filename "Readme.org")
                       (save-excursion
                         (goto-char (point-min))
                         (re-search-forward (concat modified-re " +Readme.org_archive")
                                            nil t))
                       (save-excursion
                         (goto-char (point-min))
                         (re-search-forward "\\-\\*+ DONE" nil t))
                       (not
                        (save-excursion
                          (goto-char (point-min))
                          (re-search-forward "\\+\\*[\\+\\-] TODO" nil t))))
              (goto-char (point-min))
              (insert "; Archive DONE")))))
      
      (add-hook 'git-commit-mode-hook #'gk-git-commit-mode-hook)
      

      Hope you find it useful.

      12 votes