A colleague of mine just came across a rather interesting edge case when working with Python global variables. Of course, most of the time, you should just try to avoid them altogether, but if you do use them you might come across this. If you have a global variable, and you assign to it in a function without using the global keyword, your code will fail to compile. This can result in a confusing error message. Here’s a simplified example: ...

There are plenty of reasons why what I’m trying to do might be a bad idea, and I won’t bother to go into them, but suffice to say that I know that Docker isn’t really about virtual machines that persist, and I know that it doesn’t really like running on 32-bit machines. That said, I had a linux VM and a Vagrantfile that could spin up a build environment for a project, and I wanted to try out Docker as a Vagrant provider, so I did. It was messy, but it worked, sort of, so here are my notes, in case they help someone else. There were a lot of bits of this investigation and I’ve done my best to lay them out in the right order. ...

Coming from a rails background it seemed a bit odd to me that a relationship doesn’t create a query that you can continue to work with. That might sound a bit odd, so let me show you what I mean: Don’t worry though! If you set your relationship to be dynamic, your relationship will always be returned as a query object, that you can continue to work with. This enables queries like “Find all the addresses that match this criteria from this user”. ...

Took me a while to figure this out so I thought I’d blog it. If you’re using tmux and know of a command that you want to execute, but it’s not bound to anything (the example I had was clear-history) you can type leader-: (So, by default, C-b :) and then type the command’s name. All of the commands can be found in the man page, which is pretty intimidating, but quite complete.

There’s always bad code in projects, and like it or not, it is inevitable that you will come across a big old chunk of it sooner or later. You can’t really see it as a bad thing: every programmer should be embarrassed by their old code to some extent, and the nature of the projects we work on usually means that code stays in production for years. So, bad code is a fact of life, and as such, refactoring should be constantly on the table. Refactoring old code doesn’t need to be a huge thing, or a massive project that needs undertaking: it can be many small steps. Each day, you have the opportunity to tidy up a few files, write some tests, and generally improve your codebase. ...

I’ve been playing Heroes of Newerth for the last month or so, and it’s caused me to think a lot about the pros and cons on free to play models. The basic idea is that, instead of charging £30 upfront for a game, you release it for free, with some significant limitations, and charge for the removal of those limitations. A lot of MMO games are moving over to this model, and League Of Legends has led the way in the MOBA/ARTS (whatever we’re calling it) scene. ...

DSLs are becoming a little more popular in Python, now that Django is gaining popularity, and as they appear, I know that we’re going to see a few bad patterns showing up as well as a load of great stuff. I wrote a pretty big DSL to describe plans in Billmonitor, so I’ve made a few mistakes myself, so I thought I’d write the lessons I learned along the way. Everything You’ve Written Before Is A DSL Every time you write a program, you define new words that you then put together to create something else. You’re writing your own language that defines things that relate to your domain. That’s all a DSL is - don’t make the mistake of thinking that your DSL is anything special, it’s just another program. It’s sort of a special case of programming - something that you fully intend other people to use, presumably without knowing the rest of the language. And as we all know, special cases aren’t special enough to break the rules. ...

I didn’t end up using apt-get, because it installs most of X in the process of installing XULRunner, but if you want a Mongo recipe, here’s one that should work, more or less. Your mileage may vary, I haven’t tested it out all that thoroughly.

In the Starcraft 2 galaxy editor, you can attach events to triggers, the idea being, when the event happens, the trigger fires. In the map I’m working on, a train moves through a series of points, so I thought what I’d do is, issue the train with an order to move to the next point it needs to reach, and have it fire an event when it gets there. I stored the points that it had to move through in an array and kept a pointer to the current location in the array. ...

I’ve been getting into Starcraft 2 lately, and I’ve found myself quite interested in making maps. I tried to publish my first today, and was greeted by a most unfriendly error. As the progress meter ticked up, somewhere between 80% and 100% it would fail, with the error message WORKING_SET_INSTANCE_FAIL. Completely confused by this, I googled around for a while, and no-one seemed to have a concrete solution, so I tried a few and hit on something that worked: I deleted the players colours from the Map -> Player Properties window. ...