Myths About Code Comments

theodp writes "Jason Baker gives his take on the biggest misconceptions about code comments: 1) Comments are free ('When you update the code that the comment references, you usually have to update the comment as well'). 2) Comments make code more readable ('by far the most pervasive myth that I've encountered'). 3) You should comment every function, method, class, and module ('documenting something that needs no documentation is universally a bad idea'). 4) Code must always be 'self documenting' ('would you rather use a one-liner that requires a 3-line comment, or a 10-liner that requires no comments?')."

Comments

Re:One person's myth is another person's fact.

[v1]

I find the most important comments are those that tell you WHY something was done the way it was. I do this with my own code when I track down and fix a bug that turns out to be caused by some very subtle effect or easily made mistake. I put the comment there to stop myself (or someone else) from "fixing" / "cleaning it up" later because they don't realize why it's done the way it is. Comments like:

# yes, 1, not 0. If all four of the lists are allowed to go to 0, we will blow up later with DBZ.

And having a sometimes very poor memory of code written long ago, this saves me from myself more than others.