Global Day of Code Retreat or Thoughtworks buys me Beer

So I worked all weekend this week. I won’t get paid. I won’t even get a nod from my boss, although I was there for even longer for a standard work day. Jerks. Time to burn the office down. Get my stapler back.

OK, so they’re not jerks, and I wasn’t working at work. I was at Brisbane’s Global Day of Code Retreat, taking generous advantage of the Thoughtworks office’s fridge and wifi.

The idea is that you spend a day focusing on implementing the same thing over and over, so you can hone your professional skills. In the same way as a sculptor might practice straight lines over and over, we implemented Conway’s Game of Life using TDD techniques in 45 minutes. Every 45 minutes you had to delete your code and tests, debrief, and start again with a new constraint. Some of the constraints felt more annoying then educational, but on the whole I felt I got something out of every session. I also got to teach a couple of people something about TDD & RSpec, and I love helping others improve, so I got a kick out of being able to contribute like that.

I’m going to post how I found each session today, then mull over the others and post some observations a little bit later. I think it’s best to see how learning effects you in other contexts (like actually at work) before you jump into critiquing it, so I’m going to see how the next work week goes.

Session 1

Language: Ruby
Testing Framework: RSpec

This session just booted people off into implementing Conway’s life. I worked with a young Thoughtworker whose name eluded me, and we got about halfway into an implementation before time was up.

We spent the majority of this session just discussing what way to do things. I was a big fan of using a “Cell” object which maintained a list of its own neighbours, without directional information because it doesn’t matter. Doing it like this allows for arbitrary topologies (And I suspected that might be one of the constraints.)

Potentially tricky issues with this approach include implementing the tick for every cell at once(If you duplicate the cells, you have to duplicate the network and ensure you’ve duplicated every cell with its new state. If you mutate the network in place, each cell needs to know if it’s neighbours have ticked, and if so, what their state was last tick.

At the end of the session we had a discussion about what techniques people tried. Having a “Cell” object was quite popular (OO is like herpes, it spreads with contact), there was one “have a universe holding an array of cells” solution, and the one which I liked most, which was using the co-ordinates of the cells as a key for a hash of booleans, representing whether the cell is alive or dead. I really liked this… It’s unbounded (unlike an array in many languages) and *doesn’t* require a hojillion objects.

Session 2 – Ping Pong

Language: Ruby
Testing Framework: RSpec
Constraint: Each time you write a test, you ensure it tests properly, then you pass it to your pair and they have to do all the implementation. Then they write the next test, and you implement that

This session we decided to try the hash technique one of the groups suggested last time. I say”we decided” but actually mean “I decided”, because prevarication frustrates me, my partner had no strong opinions and I thought it sounded interesting so I made a snap decision.

The Ping Pong criteria is how I’d probably prefer to do pairing in the future, although usually it irks me (I need to be doing something and my “I’m not doing anything” behaviors usually irritate my pair). It meant that your tests had to be higher quality, and there was a defined place where you had to hand over to the other member of your pair — No long stints at the keyboard or just watching.

We didn’t get an implementation finished though, although I worked out how I’d like to derive neighbours. I proceeded to teach people a tiny bit of matrix math all day (more on that later)

Session 3 – Silent Ping Pong

Language: Ruby
Testing Framework: RSpec
Constraint: The same Ping Pong TDD as before, but this time you’re not allowed to talk

I paired again with a Thoughtworker this time, a gent from China called Hiyun (I hope, sorry if I’m wrong mate >.>). Wow. Dude was a shortcut pro. I learned a shittonne of RubyMine shortcuts and tricks I’d always wanted too but never devoted time to (Which is obviously my fault). It was really cool, probably my favorite session of the day.

We went back to the “Cell as self aware object” paradigm (drink). With the exception of a couple of inadequate tests, this session worked remarkably well. The inadequate tests required a lot of gesticulating. Once you’ve written something it’s hard to prove that the test is wrong rather then the code.

I think not being able to talk focused our attentions on communicating *only* our requirements through tests. There was no discussions of where you worked, what you thought of Test::Unit VS RSpec, why’s DHH’s hair like that; it was purely a “get shit done” event.

I think the most surprising thing was that we finished. It was almost like being unable to design architecture by consensus made one arise naturally out of requirements, which I am… skeptical of. I’m not sure how well our solution would have accommodated change, but maybe most software projects are simple enough that it doesn’t matter.

Session Four – No Primatives

Language: Ruby
Testing Framework: RSpec
Constraint: Rather then using native types to store results, cells and so on, use a wrapper class or object. No Arrays of cells, no Object.live? returns true

Oh god so hard. Getting away from primitives in Ruby is hard. Every time I wanted to wrap something I heard a tiny voice in my head stop talking about bees, games, cooking and Alice in Wonderland for a minute to scream “NEEdleSS ComPleXItY!“. All I wanted to do was use built in objects so I could rely on methods that Someone Else Has Tested™.

This session, we did something horrific. We decided that, if we weren’t going to use primitives, we’d use something as far removed as possible. Something so non-primative it’d make your eyes haemorrhage.

Files.

Yup. Files. To check if there was a cell at (4,5), you checked the directory ./data/4 for file 5.cell. If it existed, it was alive. Touch a location to make a cell alive, rm to delete it. We were planning to store the current generation number in the file to allow for ticking.

How’s that for non-primitives, bitches?

Session Five – Tests must pass in 3 minutes

Language: Java
Testing Framework: JUnit
Constraint: Once you start writing a test, you must write code to make it fail in three minutes or less. If you get to three minutes without it passing, you must revert all you changes and delete your test

The intent of this constraint, I believe, was to force you to test small amounts of functionality rather then huge sweeping changes. The idea is that small tests are good tests, and it’s tempting to write large tests that try to do too much. When they fail, you’re not actually sure why, and you lose much of the advantage of a full test suite.

My pair (Hi, Mike!) and I chose Java because it was our lingua franca (Scala was preferred but it’s quite hard to use a language without a dev environment, oddly enough). This may not have been the wisest choice, because of one simple truism:

Fuck me Java is Verbose!

It’s not just the punchline to the “what’s wrong with other people’s languages” joke. It was never really bought home to me just how verbose Java was until I had to spend so much time setting up each test. I’d just spent most of the day writing Ruby and now I’m having to give all my tests annotations and a typed, static method signature, and set up my variables types, and then set up and type the method and ensure to return the right sort of thing, and just making so much boilerplate it nearly made my eyes bleed (I propose we call this Stigjava.)

Even Mike, who writes Java for a living, was surprised. He said it bought Java’s verbosity into stark relief after a day of writing Ruby and Haskell. It forced us into doing true TDD because otherwise we simply couldn’t make a test that tested anythingin time. We had to implement the minimal amount every single test pass. Here’s how we had to test that we could get a list of neighbours for a cell:

  • Write a test to ensure that there is a “getNeighbours” method. Just that one exists. Pass it

  • Write a test to ensure the method returns an (empty) ArrayList. Pass it.
  • Write a test to ensure the method returns an ArrayList containing eight things
  • Run out of time because it took so long to learn how much code we could write at once

It was just astonishing. I’m not Java bashing (so passé), just really surprised. Writing the code to pass things, and even the tests, wash’t too hard, just getting to a point where we could do something took forever. And Mike is an IntelliJ wizard – Otherwise we’d have been screwed. He was making sweet combo love to the keyboard to bust out methods and variables and implement the signatures correctly and we were still fighting the clock.

Session Six – No Returns

Language: Ruby
Testing Framework: RSpec
Constraint: None of our methods could return values.

Woah. OK. Globalling it up. During this session I had a bit of an idea how to use events to generate a grid of neighbors, but didn’t implement it cleanly. Actually, this session was embarrassing because I forgot that Ruby is pass-by-reference, so resorted to using Globals. Don’t tell my mother. The solution wasn’t really productive, just because every time I manipulated the global objects I felt dirty and wanted to cry.

During this session, the pair using Haskell gave up on the constraint and just started trying to get it working at all. Globals were popular (at least we weren’t alone wallowing in filth) and only one group used callbacks. The idea I’d had was callback/eventing based, but wasn’t async, so obviously I need to do a bit more work about doing that kind of programming at need, rather then when forced.

Then, we had beer, a debrief and a powwow. Roughly half the room left straight away and the rest wanted to hang for a bit, which I always enjoy. I’m looking forward to the next one. I’m thinking this time, we use the presence of machines on a network as live cells….

 
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  1. Tom says:

    I know this comment is a bit late but, great writeup of the day. Good to reflect on the sessions.

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