Content tagged org-mode

Introducing ox-coleslaw

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I have a big problem: I can't write a blog in anything other than Org mode. I have another problem: I haven't found a good way to write a blog only in Org mode. This always keeps me going back and forth between blogging systems. I've used tekuti, WordPress, and I've tried a few others. Currently I'm using Coleslaw. I haven't written anything lately though because it supports Markdown and HTML and I was getting antsy for some Org mode again. So I've been on the lookout for something new.

Well… I've had enough. I'm not going away this time. I'm going to fix my problems and commit to this system. I picked Coleslaw because it's written en Common Lisp and has some interesting features. I'm going to write an exporter for org to whatever Coleslaw needs!

I've known that it's pretty easy to write an exporter for Org mode for some time, but I've never actually tried to write one. I modified some bits and bobs on org-blog, but that didn't really work out. Today though, while reading an old(er) post on Endless Parentheses, I ran into ox-jekyll. Jekyll has a pretty similar page/post definition syntax to Coleslaw, so it seemed easy to read what they're doing and copy the relevant parts. It's a very small Emacs Lisp file, which made it very easy. So congrats to them and the people writing Org mode for making some very clear code.

So I wrote (or copied) ox-coleslaw based on ox-jekyll. It's slightly smaller than ox-jekyll because, frankly, it offers less. I just need a simple way to export a .org file to a .post file, nothing fancy.

To write posts I will use Org mode. Once ox-coleslaw is loaded I use the org export function to export it to an HTML file with the proper header. You can also do this non-interactively from, for example, a Makefile, but that is a story for another time.

This document is the first attempt at publishing a blog post using ox-coleslaw.


Filtering org tasks

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I want to be able to easily see a list of tasks that are relevant to the currently loaded desktop file. As I use desktop.el as a kind of project system, this means I only want the tasks for the project I'm currently working on.

First I wrote the tagify function, because org-mode tags can't contain . or - characters (among others I'm sure, but these are the only ones that have caused me any trouble so far). It's a simple string replacement:

(defun tagify (str)
  "Remove dots, replace - with _ in STR."
  (replace-regexp-in-string
   "-" "_" (replace-regexp-in-string "\\." "" (downcase str))))

Then I wrote a function to filter the task list by not showing anything that wasn't tagged with the name of the currently loaded desktop, unless it isn't tagged at all or no desktop has been loaded. And set this function to be the value of org-agenda-before-sorting-filter-function.

(defun filter-by-desktop (entry)
  "Return ENTRY if it has no tags or a tag corresponding to the desktop."
  (require 'desktop)
  (let ((label (when desktop-dirname
                 (tagify (file-name-base
                          (directory-file-name
                           (expand-file-name desktop-dirname))))))
        (tags (get-text-property 0 'tags entry)))
    (when (or (null desktop-dirname) (null tags) (member label tags))
      entry)))

(setq org-agenda-before-sorting-filter-function #'filter-by-desktop)

This works fine. I keep untagged tasks in the list as well because they might be important at all times and I don't want them falling through the cracks. I also want a complete list if no desktop has been loaded so I can browse through my tasks and decide what I'm going to do next.

The downside of this solution is that I have to close my current project in order to see the whole list.

Then I discovered the / key in the agenda buffer. I can't believe I didn't notice this key before. Anyway, that changed my solution.

Instead of setting org-agenda-before-sorting-filter-function I add a hook to the org-agenda-finalize-hook. The filter-by-desktop function looks a little different now:

(defun org-init-filter-by-desktop ()
  "Filter agenda by current label."
  (when desktop-dirname
    (let ((label (tagify (file-name-base
                          (directory-file-name
                           (expand-file-name desktop-dirname))))))
      (org-agenda-filter-apply (cons label nil) 'tag))))

(add-hook 'org-agenda-finalize-hook 'org-init-filter-by-desktop)

I don't need to compare any tags now, and if I want to see my entire list of tasks I can easily just press / /. Since it is easier to get back to the overview of my tasks it also doesn't bother me so much that this way any untagged tasks don't show up in the filtered buffer.

I haven't stopped using / since I discovered it. Filtering in this way is one of the things I like about ibuffer as well, now for org-mode it works excellently as well.


Some quick git diff tips

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A couple of quick tips. As you possibly know you can specify some options to be used for diffs (and other things) per file type. The one I'm interested in is the function name.

For org-mode

The primary way of identifying which part of an org-mode document a change occurs in seems to me to be the heading. So, in your $HOME/.gitconfig put:

[diff "org"]
      xfuncname = "^\\*+.*"

Which should show any lines starting with one or more * characters. And then in $XDG_CONFIG_HOME/git/attributes or $HOME/.config/git/attributes put:

,*.org   diff=org

For lisp and lisp-like langauges

For anything that resembles lisp (so Common Lisp, Emacs Lisp, Hy, scheme, etc.) I would think that the easiest thing to do is just see the closes top-level form. So, in your $HOME/.gitconfig put:

[diff "lisp"]
      xfuncname = "^\\([^ ]+ [^ ]+"

Which should show the opening parenthesis and the first two words. For example:

(defun some-function-name
(defclass my-awesome-class
(define-route this-strange-route

And then put in your $XDG_CONFIG_HOME/git/attributes or $HOME/.config/git/attributes:

,*.lisp  diff=lisp
,*.el    diff=lisp
,*.hy    diff=lisp
,*.scm   diff=lisp

And possibly any other lisp-like language files you can think of.


Org examples on github

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github has an org-mode parser for their README files, but I always thought it didn't handle #+BEGIN_SRC and #+BEGIN_EXAMPLE style blocks. And I'm not wrong, but it does handle : blocks.

So this won't work:

#+BEGIN_EXAMPLE
  This is an example
#+END_EXAMPLE

But this will:

: This is an example

That was a nice surprise for me, because I prefer org-mode for almost all of my documents.


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