Saturday, October 3, 2009

Everything Takes Longer In C++

So I had tonsil surgery last Monday. Even though I didn't feel up to programming for my day job, I couldn't stay away from trying to work on the MMO game project called Emergence that Ben and I are creating. When it seems like progress is going glacially slow on our game Ben and I always say "if only we had more free time to work on this..." Well I've had time this week - and I still made only baby steps in progress on it. Granted I was resting from surgery and on pain medicine, but still... I'm beginning to think it's not (just) that we have no free time. It's that with programming you put in enormous effort yet make only incremental progress.

If it takes a certain amount of effort to write software of a given complexity, writing software that's twice as complex doesn't take twice as long, it takes, I don't know, ten times as long, twenty times as long. The effort increases exponentially. Invert that and you get an equation that says that you only get logarithmic increases in output for every increase in effort. If you don't know what a logarithmic curve looks like, it has a knee bend. If you stay to the left side of the curve you get pretty good output for input, but as you move right it levels off quickly. To the right side of the curve, increasingly large increases in input result in increasingly small changes in output.

So I think I've been working dangerously close to right side of the curve lately, where what you can accomplish tapers off faster than the increase in effort. I've been getting better with some of the new programming techniques I'm using, and I've streamlined my build process and improved my debugging techniques. But here's the funny thing - all those improvements really just help me increase my work input. They don't directly increase the output. You see if I streamline my build process and my debugging techniques so that I can make a change and test it in half the time, that just means I can test twice as many code updates in the same amount of time. But if I'm on the inefficient side of a logarithmic curve, I may actually need to make four, or ten, or twenty times as many code changes at a time to actually double my output.

So that's what's so frustrating about this work. You run faster and faster but never seem to get anywhere. It's not hopeless though. I think the fact that the ratio of accomplishments from effort is logarithmic is some kind of fundamental law of software, but it is possible to tweak the shape of the curve. Although it will always eventually taper off, it doesn't need to taper so as quickly. I think changing the programming language you program in does the most to change this curve. C++ is very powerful and generates efficient programs, but it has a very sharp bend in its complexity curve. This is because doing anything substantial in C++ just involves so many fiddly little details, and the language does so little for you automatically. I'm not saying you can't build large systems in C++, but I am saying it probably took exponentially more work to do it than it would have to do it in a scripting language. And I'm not saying you shouldn't use C++; in order to get good performance in our game, we need to. But we're going to use both C++ and script language in our game, and I need to get out of the C++ part and into the scripting as soon as possible.

The ironic thing is that the component which is giving me all this trouble, where I'm working too far on the right side of the complexity curve, is the C++ component that will bind our C++ side of our game to our scripting side. In order to leave C++ behind I need to first overcome a trial by fire of the toughest C++ I've ever worked on.
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