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With very old code bases, you need to start removing things, otherwise it becomes unmaintainable. Sure, you need good testing and code coverage to make sure you

With very old code bases, you need to start removing things, otherwise it becomes unmaintainable. Sure, you need good testing and code coverage to make sure you did it properly, but that applies to any change. It doesn't mean that the people implementing it 15 years ago were idiots, no, it all made sense at the time. But after years of maintenance some parts grew into an abomination (losing any touch with the high-level design), and other parts are not needed because the specific gadget it was supposed to support no longer exists. If you don't refactor, you'll eventually have a landmine-ridden place where every change has impact on 10 different unrelated places. A company I worked at had this problem. They had to keep adding developers to handle bugfixes and feature requests, and it only became worse instead of better because they never made available time for refactoring. "Removing code that you don't understand" is indeed wrong and shouldn't happen, but at least if you use SCM can always look back to understand why it was added. And then remove it anyway. Believe me, that process makes sense for a factory but for source code you eventually end up with voodoo programming. The source is too complex for any human to understand, and it is impossible to teach new developers which didn't "grow into it".

mechanical_fish 15y ago
Oh, I agree that you'll eventually be unable to maintain or improve a codebase built on coincidence, just as you will eventually reach the limits of a chemical process that uses onions. For example, your onion process will be inconsistent at some level, precisely because onions are a hack with a lot of potential side effects. What breed of onions, again? How big should the individual onions be? Don't onions vary according to the soil you grow them in? So you'll probably have to take the onions out, sooner or later. But: You've got to be prepared for the real costs of that project. It is very, very tempting to tell yourself that your simple change is "obviously" going to be cheap. Particularly in software, which is not chemistry, let alone biology [1], and which is so close to being deterministic and consistent and provable -- after all, the individual components often are that simple (at least in the absence of cosmic rays and lightning strikes), and every complex program starts out simple and easy to change, and the complexity can grow so slowly that you barely perceive the day-to-day increase. So you can convince yourself that you know what's going on in a software system. And then, whoops, you make a change, and it has a side effect, which has another side effect, and then the bug reports come in, from users you may not have even realized you had. --- [1] This is why it's great to spend a little time moonlighting as a biologist: You can practice living in a world without certainty. Biologists really don't know more than a small fraction of what's going on. Even individual bacteria are mysterious. If you've been raised on physics you will be shocked by biology. You really have to learn what controls and statistics and experimental design are about when you're trying to measure a biological system.

mechanical_fish 15y ago

Oh, I agree that you'll eventually be unable to maintain or improve a codebase built on coincidence, just as you will eventually reach the limits of a chemical process that uses onions. For example, your onion process will be inconsistent at some level, precisely because onions are a hack with a lot of potential side effects. What breed of onions, again? How big should the individual onions be? Don't onions vary according to the soil you grow them in? So you'll probably have to take the onions out, sooner or later. But: You've got to be prepared for the real costs of that project. It is very, very tempting to tell yourself that your simple change is "obviously" going to be cheap. Particularly in software, which is not chemistry, let alone biology [1], and which is so close to being deterministic and consistent and provable -- after all, the individual components often are that simple (at least in the absence of cosmic rays and lightning strikes), and every complex program starts out simple and easy to change, and the complexity can grow so slowly that you barely perceive the day-to-day increase. So you can convince yourself that you know what's going on in a software system. And then, whoops, you make a change, and it has a side effect, which has another side effect, and then the bug reports come in, from users you may not have even realized you had. --- [1] This is why it's great to spend a little time moonlighting as a biologist: You can practice living in a world without certainty. Biologists really don't know more than a small fraction of what's going on. Even individual bacteria are mysterious. If you've been raised on physics you will be shocked by biology. You really have to learn what controls and statistics and experimental design are about when you're trying to measure a biological system.