Emacs

This section is about GNU Emacs, the GNU incarnation of the advanced, self-documenting, customizable, extensible, real-time display editor Emacs.

Browse pub/emacs/, if you look for other packages.

Fax Mode

Fax mode is a major mode for Emacs and it looks and works like mail mode. There are also low-level commands for sending any part of an Emacs buffer directly to the fax sub-system. Here is an incomplete list of features:

• Fully customizable. Works with virtually any fax sub-system, for example, hylafax and mgetty+sendfax.
• Fax aliases including dialing lists and recursive definitions.
• Rewriting of phone numbers, for example, automatically remove the international access code from a recipient’s phone number.
• File attachments.
• Mail address database interface. Examples for forms and edb are included.
• Output filters. Text (write-region), PostScript (ps-print-region, or ps-print-region-with-faces) and a hybrid text/TeX filter are available by default.

Fax mode is available at the Emacs Lisp archive, or download it from here.

Info Lookup

Info lookup displays the Info documentation of symbols and files according to the programming language you are editing. It is part of GNU Emacs (see file info-look.el). In Emacs 22, the command info-lookup is bound to C-h S. In Emacs 21 it is bound to C-h C-i (also known as C-h TAB).

Battery Mode

Battery mode displays the battery status of your laptop in the echo area or in the mode line. It is part of GNU Emacs (see file battery.el). You can either query the battery status with the command battery or you can display it permanently in the mode line with the command display-battery-mode.

No way is not an option

Prior to version 21.1, GNU Emacs could not visit non-ordinary files. This was quite inconvenient because, for example on Linux, the battery status information has to be read from a file in the /proc file system. To avoid yet another useless use of cat, I took the challenge to implement it in Emacs Lisp. After half an hour of digging, coding, and testing, I ended up with the code displayed below.

(defun battery-insert-file-contents (file-name)
  "Insert contents of file FILE-NAME after point.
FILE-NAME can be a non-ordinary file, for example a named pipe.
Return t if file exists."
  (let ((load-read-function 'battery-read-function)
        (load-source-file-function nil)
        (load-path '("."))
        (load-history nil))
    (save-excursion
      (load file-name nil t t))))

(defun battery-read-function (&optional stream)
  "Function for reading expressions from STREAM.
Value is always nil."
  (let (char)
    (while (not (< (setq char (get-file-char)) 0))
      (insert char))))

Nota bene: The most surprising thing was the discovery of the get-file-char function and it’s documentation string.

Word Hyphenation

I have implemented Liang’s hyphenation algorithm in Emacs Lisp. Up to now I can type M-x hyphen-show-hyphens RET and Emacs displays the syllables of the word at point in the echo area. The package supports multiple languages, hyphenation exceptions, and all the other features known from TeX. What still is to do is to merge word hyphenation into Emacs’ filling modes–which is not that easy.

A working copy of the source code is available in the pub/emacs/ directory. You need at least the file hyphen.el and a set of hyphenation patterns for your language of choice, for example hyphen-us.* for U.S. English.