On contributing to Emacs

TL;DR

Writing patch: a couple of hours. Getting permission from employers to submit patch: a couple of months. Contributing to Emacs: priceless.

Introduction

Matlab is not my favourite language. In fact, it’s one I’ve largely managed to ignore, which is remarkably lucky since it is also quite prevalent where I work.

One day though, I was morosely looking over a… rather organic mass of Matlab, and got so depressed I started procrastinating. I started watching the latest episode of Emacs Rocks, which was demonstrating a new minor mode to successively expand a selection around greater semantic units (for example, just on a page of text it would first select the word under the cursor, then the sentence, then paragraph, and so on).

This was much more interesting! I started hacking on it to make it work with Matlab. Admirably, it also came with a test suite and a request that all contributions include tests. These I finished on the weekend, fixing up a couple of corner cases they found along the way.

Flushed with a sense of achievement, I pushed to github and submitted a pull request.

Trials and Tribulations

All stories are fundamentally about conflict or struggle in some sense, and this is where mine started. The maintainer thanked me, and more-over informed me that his package had already been accepted into Emacs itself, and therefore so would my small contribution! I have had a long love affair with Emacs and virtually live in it, so I was ecstatic.

Well, ecstatic, and also rather nervous. The Free Software Foundation requires that all contributors must assign copyright over to them. Under local law, I do not in fact own the copyright, my employer does. Now, I work in a research organisation, and as it is their life-blood they are understandably twitchy about signing over IP. Clearly my patch was not going to leak valuable secrets, but it did put me in the position of needing someone in a large bureaucracy to accept responsibility for something that goes against the organisation’s grain, with absolutely no upside for them.

Merely getting to the stage of discovering what level of people might have the authority took a decent amount of time, and after the first apologetic rejection I did lose hope and let the trail go cold for a while. Eventually though I found someone who agreed, with experience releasing projects as open source and an “ask forgiveness not permission” attitude, to whom I will remain inordinately grateful. Actually getting the physical signature then took a week or so longer, but I was finally done.

Aftermath

All was not finally done, as it turned out. I gleefully informed the (patient, long-suffering) maintainer that all was finally good to go. He in turn pulled the patch in, and informed me that my tests were all failing! As it turned out, I had written my code against Emacs version 23 and he was using version 24, and the Matlab mode had received a major face-lift in between with many breaking changes. This was mainly due to me simply using what shipped with Ubuntu, but I did derive some hollow amusement that it felt like the process had taken so long my changes were all out of date! At any rate, I tweaked the patch to work against both version, and now I’m finally in a package, that at some point in the future will be in Emacs. In a very small way.

Colophon: Emacs Rhapsody

Browse any geek news site for long enough and eventually someone will mention Emacs, and someone else will reply “oh yeah, it’s a great operating system, but needs a good text editor, har har”. Very droll. The joke, in my opinion, is on them though because it is an operating system!

Some time, read up on the history of the Lisp Machines and watch a movie or two of one in action. For various reasons, not all technical, this vision of computing did not take off and we are poorer for it. Every aspect of the system, down to the metal, was not only written in Lisp but could be examined and changed by the user. Emacs makes sense in light of this: it’s essentially a poor-man’s Lisp Machine.

Emacs Lisp is not the nicest Lisp, but hacking on Emacs is fun both because what you write immediately improves how you work, and because you have that instant-turn-around where (nearly) every bit of functionality can be examined and updated, all without restarting.

Finally, if you’ve never really looked into Emacs, or only used it under sufferance as part of a Unix course or something, have a look at the Emacs Rocks movies some time. The guy is single-handedly doing an amazing publicity job, showing just what can be accomplished and surprising even veterans. And if I may say so, he also makes a very gracious and incredibly patient project maintainer :)

Mark Hepburn 06 November 2012
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