Introducing Didact.

21st century show and tell.

The other day I was busily hacking away on a post that does a walkthrough on Node.js — I know, I know, I'm a bit of a one-trick pony — but I stopped about a page in. See, I had a problem: walkthroughs are sort of a "show & tell" experience. In real life, this is a fairly seamless experience: you hold up the thing you're showing, and you talk over the top of it, explaining how awesome it is. Most presentations boil down to this, too. There's a hiccup, however, when it comes to blogging. You have to do a one-two punch of "Here's some code" and "Here's what it does", sequentially. Not to mention the fact that the code on your blog has to be tested and retested on it's own, in it's own environment. So the thing you're showing gets transformed by the act of telling about it. Eventually, due to the universal principle of entropy, the code on your blog will drift out of sync with the code on your website (as it did, unfortunately, here). It's especially hard when you try to iterate over a piece of code several times in the same post, as you end up having to make sure each piece of code works on it's own and that it still all makes sense over the course of the post. And don't get me started on changes where you have to show more than one file! It's dreadful — really dreadful.

Keeping in mind that I like to write posts with an eye towards iterating over concepts, and that I like to show examples of these iterations alongside my explanation of why I did them, an idea started to form — why not build a system to tie my blog posts to git repositories?

Further, why not tie it to Github? They've got a beautiful JSONP api that I've been trying to find an excuse to use anyway. I could tie specific sections of my post to specific revisions of a repository — and using an API, show the relevant files (or files in a directory) that have changed. It'd be great if it was hands-free, to boot; users could navigate through the repository filesystem, but it'd be nice if as they scrolled past a relevant point in the post, this API would automatically show them exactly what I wanted to show them.

Which is what just happened now.


Well, isn't that a thing? As you scrolled past the header, the viewer on the left just showed you a specific file stapled to a specific revision. What I'm showing you is part of my "tempisfugit" native git client for Node — sort of a side project that I'd love to write a bit more about later. I'm calling the API that I'm using to present this to you Didact. It works by selecting a repository from Github that you'd like to talk about, and then adding data-didact to specific tags throughout your post.

They take the form:

<h1 data-didact="8a47f966ecef391c8f42b636975472ece91c3d6e 'lib' L29">Something that triggers didact</h1>

As you scroll past this <h1>, didact will automatically focus on that path at that revision, at those lines. Cool, huh? Users can still navigate through the repository on the left if they'd like, so if you wanted to, say, show them a directory, that would absolutely fine.

In fact, let's try it:

Let's look at a directory!

Again, hopefully.

In fact, you can show them several versions of your repository over time, by changing the commit hash or tag you're pointing at — which certainly sates my urge to iterate over a concept visually.

This view is looking at the tempisfugit repository at an earlier version. Scrolling back up will go back to the previous views.

I've still got to wire up line highlighting, split views, and a way to view the current file / directory as a path. Woo.