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Simple (Back) Links in Any File

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This is the first post of my new blog series “site-lisp packages” where I introduce some packages in my site-lisp directory. Currently, I’ve collected 20+ packages, surely someone will find some of them helpful.

Recently I started to use Deft as a replacement for Apple’s Notes.app to take some technical notes. Meanwhile, Zettelkasten and org-roam has caught my eye. These links and back-links are certainly useful for organizing my notes.

Some good person has already written a package, zetteldeft, that combines deft and back-links. However, I don’t really like his use of ids. Why don’t we just use filenames to identify a file? And back-links doesn’t need a database like org-roam does, for my simple use-cases, I can just use grep.

Introducing bklink.el

bklink.el is my cheap version of org-roam that only provides two features:

  1. make links to other files.
  2. show back-links from other files.

It works in any text file format, and uses filenames as links, no ids or databases. However, it only works in these situations:

  1. All the files are in the same directory, no sub-directories.
  2. There aren’t a huge number of files.

These assumptions make the implementation simpler, and suits my notes well.

Specifically, bklink.el provides three functions:

  1. bklink-insert inserts a link to another file in the directory.
  2. bklink-show-back-link shows a small buffer below the current buffer, containing back-links for this file.
  3. bklink-rename to rename all links that points to this file.

The links inserted looks like “file name”, while the actual text is [{file name.ext}].

One thing I think I did right is the back-link buffer: it automatically follows the main buffer as you move/hide/switch to the main buffer. So I never need to manually close or move the buffer. The back-link buffer in org-roam annoys me a little, so I paid attention to get it right in bklink.el.

Here is a demo of bklink.el:

Implementation details

Because I made some assumptions on my notes, I can simplify the implementation:

  1. All the files are in the same directory, no sub-directories. So I can just use base filename as unique identifiers. This also means I can work in different directories in the same time without any conflict.
  2. We don’t have a huge number of files, so an async grep should be fast enough to get the back links. In fact, even if there are too many files for grep to handle, I have a backup plan that adds cache files, so I’m not too worried about the future.

The links are formatted as [{filename.ext}], and displayed as “filename”. This format has several advantages:

  1. It doesn’t conflict with Org Mode’s link format. Although most of my notes are in plain text format, I do have some Org files in my notes.
  2. I don’t hide the delimiters, but render them as quotes. In my experience, hiding delimiters makes editing the text more difficult (think about links in Org Mode).

In fact, I didn’t start with this format. I started with one that’s similar to zetteldeft’s, and changed it several times:

links.png

The good thing about writing your own package is that not only can you write it to fit your specific need (like the assumptions I made on my notes), but also can you change the design anytime. (This is also why I don’t publish these small packages, I don’t want to be responsible for a stable user experience.)

Apart from the “sticky” back-link buffer (read more about it in Atomic Buffer), there aren’t much to talk about. Getting back-links is just calling grep in a sub-process and installing a sentinel that parses the stdout and inserts back-links into the back-link buffer. I also added highlight for URL links, so I can click on URL’s in my note.

The funny thing about renaming is that, there is no UNIX command that can I can write in one line, or even less than 10 lines, that searches & replaces text literally. So I ended up grepping files and replace with Emacs—I grep for a list of files that contains the link, writes them to a temporary file, start an Emacs process in batch mode, load bklink.el, load the temporary file, and call a replace function I defined in bklink.el on each file.

Show me the code

Here it is. In case I change my configuration, here is a local backup.

Written by Yuan Fu <casouri@gmail.com>

First Published on 2020-07-30 Thu 15:31

Last modified on 2020-07-31 Fri 15:58