Category Archives: geek

Building a today-I-learned habit, and displaying the documentation for random Emacs commands

I’d like to build a habit of regularly learning one small thing each day in one of three domains: tech, life, and learning. My measurable output would probably be in the form of index cards, tweets, blog posts, and notes (in org-capture, Dropbox, or Evernote). I can get input from various sources like blog posts, videos, books, webpages, and so on.

2016-02-19a Preparing for a today-I-learned habit -- index card #til #learning

2016-02-19a Preparing for a today-I-learned habit — index card #til #learning

A little bit of randomness might be useful for learning more about Emacs. Emacswiki has a random page function, but the chunks are often a little large or irrelevant. On the other hand, displaying a random command from the packages that I already have loaded into my Emacs – that might be a good way to discover interesting things.

I started by looking at apropos-command, which led me to apropos-internal, which is a C function that referred to obarray. Using obarray by itself didn’t work (suspiciously few elements, so I often ended up looking at emms-related functions). I eventually found mapatoms, which seems to do a better job at listing an appreciable number of interactive functions. I filtered the list to include only documented functions that had not been marked as obsolete: 8,415 in my current Emacs, which should be plenty to go through. =)

(defun my/describe-random-interactive-function ()
  (interactive)
  "Show the documentation for a random interactive function.
Consider only documented, non-obsolete functions."
  (let (result)
    (mapatoms
     (lambda (s)
       (when (and (commandp s) 
                  (documentation s t)
                  (null (get s 'byte-obsolete-info)))
         (setq result (cons s result)))))
    (describe-function (elt result (random (length result))))))

I’ve added this to a key-chord + hydra keymap as a repeatable function, so I can type hh to start my Hydra and then type r as many times as I want in order to show the documentation for a random interactive function. If you’re curious about that, you can see the key-chord section of my config.

Anyway, today I learned more about obarray and mapatoms – they’re not interactive functions, but they were handy for building this little bit of code. We’ll see how it goes! =)

2016-02-15 Emacs News

Links from reddit.com/r/emacs, /r/orgmode, Hacker News, planet.emacsen.org, Youtube, EmacsWiki:RecentChanges, the Emacs commit log, the changes to the Emacs NEWS file, and emacs-devel.

Past Emacs News round-ups

2016-02-08 Emacs News

Links from reddit.com/r/emacs, /r/orgmode, Hacker News, planet.emacsen.org, Youtube, EmacsWiki:RecentChanges, the Emacs commit log, the changes to the Emacs NEWS file, and emacs-devel.

Past Emacs News round-ups

Publishing Emacs News as plain text, HTML, and attached Org file

Update 2016-02-05: Since @ThierryStoehr linked to this post about Emacs News-related code, I figured I’d add a link to the other support functions I’ve been using to help me with Emacs News summarization. There’s also this bit:

(let ((date (org-read-date nil nil "-mon")))
    (concat
     (my/org-list-from-rss "http://planet.emacsen.org/atom.xml" date) "\n"
     (shell-command-to-string (concat "~/bin/list-reddit-links.coffee emacs " date)) "\n"
     (shell-command-to-string (concat "~/bin/list-reddit-links.coffee org-mode " date)) "\n"
     "- New packages:\n"
     (my/list-new-packages) 
     "\n"))

Handy little things!

——

I’ve been publishing these weekly summaries of Emacs-related links on my blog and to the emacs-tangents mailing list / newsgroup. I started by posting plain text from Org Mode’s ASCII export, and people asked for Org Mode and HTML formats. So here’s some code that prepares things for pasting into a Gnus message buffer.

It turns out that order matters for multipart/alternative – start with plain text, then include richer alternatives. First time around, I put the HTML version first, so people didn’t end up seeing it. Anyway, here’s something that shows up properly now: text/plain, then text/html, with text/x-org attached. The heavy lifting is done with org-export-string-as, which exports into different formats.

  (defun my/share-emacs-news ()
    "Prepare current subtree for yanking into post."
    (interactive)
    ;; Draft Gnus article
    (save-restriction
      (org-narrow-to-subtree)
      (let ((org-export-html-preamble nil)
            (org-html-toplevel-hlevel 3)
            output)
        (setq output
              (apply
               'format
               "<#multipart type=alternative>
<#part type=\"text/plain\" disposition=inline>
%s
<#/part>
<#part type=\"text/html\" disposition=inline>
%s
<#/part>
<#/multipart>
<#part type=\"text/x-org\" disposition=attachment name=\"emacs-news.org\">
%s
<#/part>
"
               (mapcar
                (lambda (format)
                  (org-export-string-as (buffer-substring (point-min) (point-max)) format t))
                '(ascii html org))))
        (kill-new output))))

Howard Abrams showed me something like this in June 2015’s Emacs Hangout (~1:18:26) using org-mime-org-buffer-htmlize, which probably does the job in a much cooler way. =) I thought he had a blog post about it, but I can’t seem to find it. Anyway, there’s my little hack above!

2016-02-01 Emacs News

Update 2016-02-02: Added Hacker News links.

Links from reddit.com/r/emacs, /r/orgmode, Hacker News, planet.emacsen.org, Youtube, the Emacs commit log, the changes to the Emacs NEWS file, and emacs-devel.

Past Emacs News round-ups

Calibre and Qt 5.5

A recent apt-get dist-upgrade resulted in the removal of calibre and calibre-bin from my system. I’ve been using Calibre to convert e-books from HTML and EPUB (some developer references, some fanfiction =) ) and copy them onto my Kindle.

It turned out that the Calibre packaged in Ubuntu required qtbase-abi-5-4-2 and my recent dist-upgrade installed Qt 5.5. I needed to upgrade to Calibre 2.49, which wasn’t available on any of the PPAs I checked (despite instructions to the contrary).

Installing Calibre from the Calibre website made it work, though. In fact, the Calibre website says:

Please do not use your distribution provided calibre package, as those are often buggy/outdated. Instead use the Binary install described below.

I wasn’t too keen on piping the output of a wget command to sudo , but a quick scan of the script didn’t turn up anything suspicious. Anyway, now I can convert EPUBs to MOBIs and easily copy them onto my Kindle, yay!