Gnus and Google Groups

Eternal September notwithstanding, i have great daily fun reading a bunch of usenet groups, and their articles are sometimes a source of ideas for blogging. Of course, my usenet client is Gnus; but in a blog post one needs the Google Groups URL when mentioning and article. So, i just spent five minutes writing a snippet to go from Gnus to GG in a keystroke:

(defun jao-gnus-goto-google ()
  (interactive)
  (when (memq major-mode '(gnus-summary-mode gnus-article-mode))
    (when (eq major-mode 'gnus-article-mode) 
      (gnus-article-show-summary))
    (let* ((article (gnus-summary-article-number))
           (header (gnus-summary-article-header article))
           (id (substring (mail-header-id header) 1 -1)))
      (browse-url 
       (format "http://groups.google.com/groups?selm=%s" id)))))

As you see, i just check that i’m viewing a post, obtain the message identifier (trimming surrounding markup) and construct a query that looks up the corresponding GG article.

Talk about extensibility.

Tip of the Day

Although i don’t use it that much, i’ve had the following defun in my emacs config since i remember:

(defun totd ()
  (interactive)
  (random t) ;; seed with time-of-day
  (with-output-to-temp-buffer "*Tip of the day*"
    (let* ((commands (loop for s being the symbols
                           when (commandp s) collect s))
           (command (nth (random (length commands)) commands)))
      (princ
       (concat "Your tip for the day is:\\n"
               "========================\\n\\n"
               (describe-function command)
               "\\n\\nInvoke with:\\n\\n"
               (with-temp-buffer
                 (where-is command t)
                 (buffer-string)))))))

(Actually, i’ve tracked it down to a gnu.emacs.help thread dated 2001).

I’m sure you’ve guessed what it does. One possible use is to put the invocation (totd) at the end of your .emacs; but, as i tend to have emacs open for days, if not weeks, in a row, i prefer to just bind it to a keyboard shortcut and press it when i’m idling or thinking of a new post. I can also press the shortcut repeatedly until the random chosen command interests me.

Another possibility (if you don’t find it annoying), is to set a timer to get a periodic tip of the day, using something along the lines of:

(defvar jao-totd-timer (run-at-time "12:00am" (* 3600 24) 'totd))
(defun jao-cancel-totd
  (interactive)
  (cancel-timer jao-totd-timer))

Not that bad as a pastime 🙂

Emacsy OS X

Let me tell you how Emacs is more and more taking the center stage in my MacBook. In a previous post i explained how i set up Gnus as my mail (and of course, news) reader: i like Gnus so much that it quickly became my default. And, just in case you didn’t know, Emacs can be OS X’s default mail handler too: just go to Mail’s general preferences pane and set it–it’s that easy. (In the image, i’m setting fink’s carbon emacs package, but you’ll see there too CarbonEmacs or Aquamacs if you have them installed.) With that setting in place, OS X will dutifully use Gnus whenever a mail handler is requested (e.g., when following mailto: URLs, or when using ‘Send this page…’ in Safari).

Unlike Gnus, Emacs is not my default web browser, although i use w3m-el quite a bit (specially for technical manuals). So, every now and then i find myself seeing a page in Safari than i want to open in Emacs. Applescript to the rescue: fire up that ugly Script Editor and type this simple program:

property eclient : "/sw/bin/emacsclient -e "
tell application "Safari"
  set this_url to the URL of document 1
  do shell script eclient & \
          "'(w3m-browse-url \"" & this_url & "\")'"
	tell application "Emacs22" to activate
end tell

(changing the path to emacsclient and the name of your Emacs as needed). Of course, you’ll also need to start the Emacs server somewhere in your init files with (start-server), and to save the above script in ~/Library/Scripts/Applications/Safari. I’ve named it ‘Open in Emacs’, and it appears nicely as an entry in my FastScripts menu.

The last, and most interesting, bit is going in the opposite direction: accessing Safari (or any other Cocoa application, for that matter) from Emacs. Or, put in another one, executing AppleScript snippets within Emacs. One possibility is using Emacs’ shell-command in conjunction with OS X’s osascript, but there’s a sweeter way: the Elisp function do-applescript. For instance, the function jao-as-safari-doc below returns the URL and title of the active page in Safari:

 (defun jao-as-tell-app (app something)
   (let ((res (do-applescript (concat "tell application \""
                                      app "\" to " something))))
     ;; the string returned is quoted
     (substring res 1 -1)))

 (defun jao-as-safari-doc ()
   (interactive)
   (let ((url (jao-as-tell-app "Safari" 
                               "get the URL of document 1"))
         (name (jao-as-tell-app "Safari" 
                               "get the name of window 1")))
     (cons url name)))

This may seem a bit boring at first, but it can be put to good use: when i see a page worth taking a few notes, i open an org-mode buffer, and type a shortcut bound to the following function:

 (defun jao-org-insert-safari-link ()
   (interactive)
   (let ((l (jao-as-safari-doc)))
     (insert (org-make-link-string (car l) (cdr l)))
     (message "Link to %s inserted" (car l))))

and (minor) magic happens. I’m sure you can think of many other interesting uses of do-applescript, can’t you?

Emacs on the spotlight

I’ve been writing lately several snippets to improve the communication of Emacs with OS X. One of them is this quick and dirty mdfind mode that provides access, within an Emacs buffer, to the results of mdfind commands (the CLI to OS X’s Spotlight). Just put the above file somewhere in your load path, (require 'mdfind) in your init file and invoke M-x mdfind. You’ll be asked for a directory and a search string to perform in that directory. Under the rug, this shell command gets executed:

mdfind -onlyin directory query

The results (a file list) are collected in a special buffer in a new major mode (creatively dubbed mdfind-mode) that inherits from org-mode (this is Emacs 22; if you haven’t yet, take a look at org-mode: it is simply awesome), and that displays the files nicely fontified as links. See the comments at the beginning of mdfind.el for a list of available shortcuts that you can use to navigate and open (using OS X’s default handlers) the files in the list.

The functionality offered is right now limited and there’re many venues for improvement, so i guess i’ll keep adding features as i need them. But you’re encouraged to take this quick hack as an starting point to get the functionality that you deem important (and maybe share the results 🙂 ). Or, alternatively, to leave your suggestions in the comments section.