烟台炖土豆丝

  • 切丝浸入冷水中
  • 干辣椒蒜头切碎小火至略焦黄 (两三个蒜瓣对应四个土豆)
  • 放入土豆丝八角(一到两个,不要更多)炒到变软
  • 放入水,几滴醋,盖上小火焖一下,留点水

potato.jpg

Enhance emacs-git-gutter with ivy-mode

CREATED: <2016-07-14 Thu>

UPDATED: <2016-09-23 Fri>

emacs-git-gutter shows an icon in the gutter area. The icon indicating whether a line has been inserted, modified or deleted in Emacs.

I usually use M-x git-gutter:previous-hunk or M-x git-gutter:next-hunk to navigate between the hunks.

But if there are too many hunks in one file, ivy-mode is more efficient:

(require 'ivy)
(require 'git-gutter)

(defun my-reshape-git-gutter (gutter)
  "Re-shape gutter for `ivy-read'."
  (let* ((linenum-start (aref gutter 3))
         (linenum-end (aref gutter 4))
         (target-line "")
         (target-linenum 1)
         (tmp-line "")
         (max-line-length 0))
    (save-excursion
      (while (<= linenum-start linenum-end)
        (goto-line linenum-start)
        (setq tmp-line (replace-regexp-in-string "^[ \t]*" ""
                                                 (buffer-substring (line-beginning-position)
                                                                   (line-end-position))))
        (when (> (length tmp-line) max-line-length)
          (setq target-linenum linenum-start)
          (setq target-line tmp-line)
          (setq max-line-length (length tmp-line)))

        (setq linenum-start (1+ linenum-start))))
    ;; build (key . linenum-start)
    (cons (format "%s %d: %s"
                  (if (eq 'deleted (aref gutter 1)) "-" "+")
                  target-linenum target-line)
          target-linenum)))

(defun my-goto-git-gutter ()
  (interactive)
  (if git-gutter:diffinfos
      (ivy-read "git-gutters:"
                (mapcar 'my-reshape-git-gutter git-gutter:diffinfos)
                :action (lambda (e)
                          ;; ivy9+ keep `(car e)'
                          ;; ivy8- strip the `(car e)'
                          ;; we handle both data structure
                          (unless (numberp e) (setq e (cdr e)))
                          (goto-line e)))
    (message "NO git-gutters!")))

Screenshot:

git-gutter-and-ivy-nq8.png

Turn off linum-mode when file is too big

CREATED: <2016-07-14 Thu>

UPDATED: <2016-08-07 Sun>

It's well known that linum-mode slows Emacs when the file contains thousands of lines.

Here is the fix,

(defun buffer-too-big-p ()
  (or (> (buffer-size) (* 5000 80))
      (> (line-number-at-pos (point-max)) 5000)))
(add-hook 'prog-mode-hook
          (lambda ()
            ;; turn off `linum-mode' when there are more than 5000 lines
            (if (buffer-too-big-p) (linum-mode -1))))

Though nlinum-mode has performance, I still stick to linum-mode because git-gutter only supports linum-mode.

You can check the interesting discussion about git-gutter/linum-mode/nlinum-mode. Syohei Yoshida made git-gutter 95% functional when linum-mode off.

How to manage Emacs packages effectively

Here are a few techniques I developed after reading Steve Purcell's setup.

The techniques are compatible with use-package because it uses Emacs API.

Mid-level Lisp knowledge is required to read this article.

Do NOT use package.el for certain packages

Create the directory ~/.emacs.d/site-lisp. Then insert below code into ~/.emacs,

(if (fboundp 'normal-top-level-add-to-load-path)
    (let* ((my-lisp-dir "~/.emacs.d/site-lisp/")
           (default-directory my-lisp-dir))
      (progn
        (setq load-path
              (append
               (loop for dir in (directory-files my-lisp-dir)
                     unless (string-match "^\\." dir)
                     collecting (expand-file-name dir))
               load-path)))))

You can place a package's source code at sub-directory of ~/.emacs.d/site-lisp/. That's all you need to do to install packages.

Create your own package repository

Step 1, Place two files "archive-contents" and "hello-1.0.0.el" in any directory. Say ~/.emacs.d/localelpa.

Here is the content of archive-contents:

(1
 (hello . [(1 0 0) nil "Say hello" single])
)

Here is the content of hello-1.0.0.el:

;;;###autoload
(defun hello-say ()
  (interactive)
  (message "Hi, hello!"))

(provide 'hello)

Step 2, insert below code into ~/.emacs,

(add-to-list 'package-archives '("localelpa" . "~/.emacs.d/localelpa"))

Step 3, restart Emacs and run M-x list-packages. As you can see, you can install package named "hello" now!

Here is a real world example how I apply this technique. I use rainbow-mode from https://elpa.gnu.org/ which shuts down sometimes. So I built a local repository to host rainbow-mode and a few other packages to remove dependency on GNU site.

I also create a elpa-mirror which creates a local repository from the installed packages. This local repository could be converted to remote repository using Dropbox and Github easily.

Orphan package issue is also resolved by elpa-mirror. You can delete everything from ~/.emacs.d/elpa and set the repository to the local repository created by elpa-mirror. It only takes 30 seconds to install 300 packages.

Advice package--add-to-archive-contents to filter packages

Insert below code into ~/.emacs,

;; List of VISIBLE packages from melpa-unstable (http://melpa.org)
;; Feel free to add more packages!
(defvar melpa-include-packages
  '(bbdb
    color-theme
    company-c-headers)
  "Don't install any mELPA packages except these packages")

(defvar package-filter-function nil
  "Optional predicate function used to internally filter packages used by package.el.

The function is called with the arguments PACKAGE VERSION ARCHIVE, where
PACKAGE is a symbol, VERSION is a vector as produced by `version-to-list', and
ARCHIVE is the string name of the package archive.")

;; Don't take MELPA versions of certain packages
(setq package-filter-function
      (lambda (package version archive)
        (or (not (string-equal archive "melpa"))
            ;; install package in whitelist
            (memq package melpa-include-packages)
            ;; use all color themes
            (string-match (format "%s" package) "-theme"))))

(defadvice package--add-to-archive-contents
  (around filter-packages (package archive) activate)
  "Add filtering of available packages using `package-filter-function', if non-nil."
  (when (or (null package-filter-function)
      (funcall package-filter-function
         (car package)
         (funcall (if (fboundp 'package-desc-version)
          'package--ac-desc-version
        'package-desc-vers)
            (cdr package))
         archive))
    ad-do-it))

The above code builds the filter defined in package-filter-function to get the final version of packages list.

The filter accepts the package if it's NOT from melpa-unstable OR it's listed in melpa-include-packages OR its name contains "-theme".

Surely you can build your own filter.

This solution is copied from Steve Purcell's setup with a little modification.

Summary

You can combine above techniques to solve any package issue.

For example, package A is dependent on package B. Both A and B have two versions, 1.0 and 2.0:

  • A 2.0 can use B 1.0 and B 2.0, but A 1.0 can ONLY use B 1.0
  • A 2.0 can ONLY use B 2.0, and A 1.0 can only use B 1.0

The solution is simple. We create a local repository to host B 1.0 and A 1.0. As I said, package-filter-function only returns a boolean expression. So you can design any strategy.

I know some one believs "Emacs package manager sucks" after mastering it for seven years. That's certainly not the truth as I have proved. I spent 15 minutes to reach the opposite conclusion when I was a Emacs dummy.

It's possibly I started my journey by learning from experts instead of "studiyng" by myself.

New git-timemachine UI based on ivy-mode

UPDATED: <2016-09-23 Fri>

CREATED: <2016-06-05 Sun>

When using git-timemachine, I prefer start from my selected revision instead of HEAD.

Here is my code based on ivy-mode,

(defun my-git-timemachine-show-selected-revision ()
  "Show last (current) revision of file."
  (interactive)
  (let* ((collection (mapcar (lambda (rev)
                    ;; re-shape list for the ivy-read
                    (cons (concat (substring-no-properties (nth 0 rev) 0 7) "|" (nth 5 rev) "|" (nth 6 rev)) rev))
                  (git-timemachine--revisions))))
    (ivy-read "commits:"
              collection
              :action (lambda (rev)
                        ;; compatible with ivy 9+ and ivy 8
                        (unless (string-match-p "^[a-z0-9]*$" (car rev))
                          (setq rev (cdr rev)))
                        (git-timemachine-show-revision rev)))))

(defun my-git-timemachine ()
  "Open git snapshot with the selected version.  Based on ivy-mode."
  (interactive)
  (unless (featurep 'git-timemachine)
    (require 'git-timemachine))
  (git-timemachine--start #'my-git-timemachine-show-selected-revision))

Screenshot after M-x my-git-timemachine,

my-git-timemachine-nq8.png

Complete line with ivy-mode

Complete current line by git grep and ivy-mode.

(defun counsel-escape (keyword)
  (setq keyword (replace-regexp-in-string "\\$" "\\\\\$" keyword))
  (replace-regexp-in-string "\"" "\\\\\"" keyword))

(defun counsel-replace-current-line (leading-spaces content)
  (beginning-of-line)
  (kill-line)
  (insert (concat leading-spaces content))
  (end-of-line))

(defun counsel-git-grep-complete-line ()
  (interactive)
  (let* (cmd
        (cur-line (buffer-substring-no-properties (line-beginning-position)
                                                  (line-end-position)))
        (default-directory (locate-dominating-file
                            default-directory ".git"))
        keyword
        (leading-spaces "")
        collection)
    (setq keyword (counsel-escape (if (region-active-p)
                                      (buffer-substring-no-properties (region-beginning)
                                                                      (region-end))
                                    (replace-regexp-in-string "^[ \t]*" "" cur-line))))
    ;; grep lines without leading/trailing spaces
    (setq cmd (format "git --no-pager grep -I -h --no-color -i -e \"^[ \\t]*%s\" | sed s\"\/^[ \\t]*\/\/\" | sed s\"\/[ \\t]*$\/\/\" | sort | uniq" keyword))
    (when (setq collection (split-string (shell-command-to-string cmd) "\n" t))
      (if (string-match "^\\([ \t]*\\)" cur-line)
          (setq leading-spaces (match-string 1 cur-line)))
      (cond
       ((= 1 (length collection))
        (counsel-replace-current-line leading-spaces (car collection)))
       ((> (length collection) 1)
        (ivy-read "lines:"
                  collection
                  :action (lambda (l)
                            (counsel-replace-current-line leading-spaces l))))))
    ))
(global-set-key (kbd "C-x C-l") 'counsel-git-grep-complete-line)

I also tried grep which is too slow for my project.

Make Messages Buffer modifiable in Emacs 24.4

(defadvice switch-to-buffer (after switch-to-buffer-after-hack activate)
  (if (string= "*Messages*" (buffer-name))
      (read-only-mode -1)))

How to input Non-English character in evil-mode efficiently

You can M-x toggle-input-method or C-\ to input Non-English characters.

Analysis about evil-mode,

  • You only input Non-English characters in evil-insert-state. So you need go into evil-insert-state at first before toggle on input method
  • In evil-insert-state, you can toggle off input method to input English characters while staying in evil-insert state
  • When press ESC, you quit from evil-insert-state. But input method could be still activated. So when you re-enter evil-insert-state, you need notification of input method status

Here is the setup,

;; {{ make IME compatible with evil-mode
(defun evil-toggle-input-method ()
  "when toggle on input method, goto evil-insert-state. "
  (interactive)

  ;; load IME when needed, less memory footprint
  ;; (unless (featurep 'chinese-pyim)
  ;;   (require 'chinese-pyim))

  (cond
   ((and (boundp 'evil-mode) evil-mode)
    ;; evil-mode
    (cond
     ((eq evil-state 'insert)
      (toggle-input-method))
     (t
      (evil-insert-state)
      (unless current-input-method
        (toggle-input-method))
      ))
    (if current-input-method (message "IME on!")))
   (t
    ;; NOT evil-mode, some guy don't use evil-mode at all
    (toggle-input-method))))

(defadvice evil-insert-state (around evil-insert-state-hack activate)
  ad-do-it
  (if current-input-method (message "IME on!")))

(global-set-key (kbd "C-\\") 'evil-toggle-input-method)
;; }}

Chinese version:

在evil-mode中切换输入法有以下要点,

  • 输中文前须进入evil-insert-state
  • 在evil-insert-state中可能会切换输入法
  • 按ESC退出evil-insert-state时输入法可能还开着,所以再进入evil-insert-state时需提示输入法状态

代码见上.

Swiper/Ivy tip

Please install evil-escape at first.

When Swiper/Ivy candidate window pops up. You can press fd quickly to close the window.

fd is the default key binding from evil-escape. I changed it to kj instead.

Use general.el to provide multiple leader key in evil-mode

General.el "provides a more convenient way to bind keys in emacs for both evil and non-evil users".

I have been using it for more than one month without any issue. I prefer general.el to evil-leader because I need both comma and space key as leader key.

Minimum setup is simple,

(require 'general)
(general-evil-setup t)
(nvmap :prefix ","
       "bb" 'back-to-previous-buffer
       "ww" 'save-buffer
       "oo" 'compile)

;; all keywords arguments are still supported
(nvmap :prefix "SPC"
       ; save windows layout
       "ss" 'wg-create-workgroup
       ;; load windows layout
       "ll" 'my-wg-switch-workgroup)

My real world setup is more complicated.