Cleverness Considered Harmful

I have just read this nice quote at the stackoverflow question “Why is cleverness considered harmful in programming by some people?”:

Fools ignore complexity; pragmatists suffer it; experts avoid it; geniuses remove it.

– Alan Perlis

Which reminds me of a little code piece I have written recently. I’ve recently tried to implement a small, little parser for a very simple custom data format, in C++. To do this, I have tried several approaches:

1. Boost.Spirit

Since we use Boost in our projects, I have started reading about Boost.Spirit, and took some time to decipher the tutorials which contains code like this:

bool r = phrase_parse(first, last,
  //  Begin grammar
  (
      '(' >> double_[ref(rN) = _1]
          >> -(',' >> double_[ref(iN) = _1]) >> ')'
  |   double_[ref(rN) = _1]
  ),
  //  End grammar
  space);

After half an hour I got annoyed because it simply is too much effort. I don’t care how well thought out the library is and how powerful it is, it is simply unusable. Maybe I am too stupid, but I am sure that even when I manage to understand it enough to write a decent parser, half a year later I can never debug my code again: it’s simply too clever.

2. Coco

I’ve ditched Boost.Spirit, and tried to use Coco. I am unfamiliar with this but have seen a colleague use it, so I gave it a try. I was reading the documentation, which looks nice but has 42 pages and since I am a lazy bastard I stopped right there because I just want to get something working, and quickly.

3. Hand Written Large Switch

I have ditched Cocomo, and started to write my own, very simple code that basically looked like this:

while (instream >> sym) {
  switch (symbol_map[sym]) {
  case START:
    // do this
    break;
  case WHATEVER:
    // do that
    break;
  }
}

After just 10 minutes I got a minimal parser that worked good enough and was extremly readable and understandable code. Everybody with basic C++ understanding can skim over this code and get it. The number of WTF’s per minute when reading this code is close to zero. I am very happy with this approach, and it really rocks because it is so dead simple.

You can rightfully say that a simple switch is very inflexible, and not extensible. You are right, but who cares? Almost all code that I have seen that was planed ahead for flexibility that you might need, gets too complicated because what you planed ahead for might never be needed; even worse: most of the time you need flexibility that you cannot know in advance, it only becomes apparent when you have something and running and use it for a while.

Final Words

Back to the original quote, based on my experience I would extend it a bit:

Ignorants add complexity; fools ignore complexity; pragmatists suffer it; experts avoid it; geniuses remove it.

– Martin Ankerl

If you find this interesting you might also like consider reading the Three Laws of Software Development.

What do you think?