Monday, July 30, 2007

A brief reaction to "Find the Bug"

I picked up a copy of Adam Barr's Find the Bug, which is a cool concept for a book. (5 languages, 50 programs, 50 bugs; see if you can spot them.)

I found the bug in the first program, in C, then skipped to the Python chapter. The first two programs were not too bad, as pedagogical exercises go (although iterating through substrings instead of a.startswith(b) in the 2nd was painful). The third, though, was "Alphabetize words," 25 sloc to perform the equivalent of

def alphabetize(buffer):
  L = buffer.split(' ')
  return L

... doing everything about the hardest way possible.

Now, it's pretty hard to introduce a non-obvious bug into my version of this function, so it wouldn't be appropriate for Mr. Barr's book when written this way. But the right thing to do is to make the task more difficult, not dumb Python down to the level of C! It's very very painful to read Python written like that.

(Actually it's painful to read any language written at such a low level of expressivity, which is why I prefer not to use languages that really can't do any better.)


Tim said...

You mean like:
return sorted(text.split())

Jonathan Ellis said...

Yes, except the book was written when python 2.2 was the latest, so sorted() wasn't available. And the book's code also just allows space as a word delimiter rather than any whitespace. I was trying to be fair, I guess to the point of pedantry. :)

yuvlevental said...


I really like your website. I also have a blog about python, It's about my adventures concerning my learning of python So anyway, I have a couple tutorial requests. Can you post a tutorial explaining how to make exe, dmg, bin/deb/rpm files? And can you create a tutorial about how to make a simple Jython game?

Tim Lesher said...

Q: What happens when you don't read a blog post carefully?
A: You spend five minutes staring at a three-line function, trying to figure out where the bug is.

Nice tip, though.... I'll have to add that book to my "to-read" list.