Thoughts etc.


Writing Emacs skeletons

19 Jan 2014

I use Emacs to write markdown (GitHub flavored markdown) and have written quite a bit of it the last couple of months. So far I haven't used any special tools beside the Emacs markdown-mode.

I was wondering if Emacs might be able to help me out, and I started looking at different Emacs modes and quickly discovered that they use something called tempo (or tempo-mode) to generate code skeletons.

There is an entry about tempo on EmacsWiki, but frankly, the examples I tested there just didn't work. I don't know if the documentation hasn't been properly updated. I am using Emacs 24.3.1.

Before doing anything else, don't forget to load the tempo package: (require 'tempo).

From the EmacsWiki and the Emacs modes I quicky learned that the important function for defining a template was the tempo-define-template function, which has a compact but good description (C-h f tempo-define-template) on how to write code templates.

Consider the following example:

   n r p n
   "```" n ))

When this is executed, tempo-define-template generates the function tempo-template-markdown-highlight-erlang. Invoking the generated function will insert the following at point, placing the cursor in between the begin and end markers:



The above is an example of GitHub markdown, marking a piece of text as erlang code and highlighting it as such.

The meaning of the special characters n, r and p in this example are:

p: Where to place the cursor after inserting the template.

r: If a region is selected, replace the region with the template and insert the region at this point.

n: Insert newline.

Note: this is not the complete meaning of the above symbols, and there are several more like > (meaning indent line). Consult the description of tempo-define-template for more information.

Mode activation

We need to add this to the context of the mode where we will use the skeleton. We can add the following to our .emacs:

(defun my-markdown-model-keys ()
  "Add my keybindings to `markdown-mode'."
  (local-set-key [f5] 'tempo-template-markdown-highlight-erlang))

(add-hook 'markdown-mode-hook 'my-markdown-model-keys)

Here we define a function my-markdown-model-keys which locally binds f5 to the generated template function tempo-template-markdown-highlight-erlang, and then we add the function to the markdown-mode-hook.

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