I’m fixing code written by some quite junior programmers. I’m always amazed at the code people write. Only in these moments I really see what good code is about. When you read or write good code, it just seems the obvious thing to do, and no big deal.
Principle #1: if one small piece of code is repeated, and it would be wrong if you changed it in one place but not the other, then THE CODE IS BAD! You have to REWRITE it. Just so that you can’t change things in one place and not in the other(s)! It’s that simple.
The simplest case, and one I STILL see too often is numeric constants. You are adjusting some things (say, things in a UI layout done programmatically). You change it in one place, run the program, and it doesn’t work. Or you do something non-direct (like rotating the screen and then going back to the original place), and things break up. You check it, and the position is set in two places, to a numeric constant, and you had only changed it in one place!
The solution is obvious: have a #define at the top giving the right name to the value, and use the constant name in both places. In Java, you can just use some “private final static int” or so. Whatever your languages buys you, but there’s certainly a way (or switch languages, pronto!).
I had this idea that if someone indents code wrong, you should stop looking at it, because the rest will be wrong too. If a developer can’t get indentation right, it’s impossible they’ll get conceptual consistency right. I’m expanding on this idea now: if someone repeats small non-independent pieces of code or numeric constants, instead of refactoring to some simple function or definition, then I won’t bother with it (unless totally unavoidable).
May you never break the DRY principle: Dont Repeat Yourself. I have a theory that every good development practice boils down to just a circumstancial version of this principle. There is one practice that doesn’t fit the bill, so that’s why I’m withholding from sharing until I can really prove the elegance. I can boil all down to “WRITE HONEST CODE”, but that just isn’t so catchy.