There’s nothing more appealing than thinking you’re just that good. Our brains are optimized for fondly remembering our successes and quietly downplaying our failures.

The casinos in Vegas are primed for this by making it relatively likely you’ll win something early on. By the time you realize that the slight edge of the house means over the long run it’ll win everything back and more, well, you’ve probably spent more than your first ATM stop and then some.

Future coding is a lot like playing the roulette. If you can guess where the requirements of tomorrow will land today, you’ve just scored the ultimate programmer’s prize: looking like a wizard. You saw the future and you were right! High five, brain!

That’s the almost irresistible draw of “flexibility”—often just a euphemism for building half or whole features before you know how they’re supposed to work or whether you need them. Just like in Vegas, the worst thing that can happen is to be right about this once in a while.

Because like the casinos, the house of program complexity will take all your little bets on the future and add them up until you just don’t know how this damn program got so deep into technical debt!

Running up the debt on your code is not just about the quick hacks and dirty commits you know you really should clean up (but just don’t). No, the far more insidious kind of debt is that acquired in the name of “flexibility”.

Every little premature extraction or abstraction, every little structure meant for “when we have more of this kind”, every little setting and configuration point for “things we might want to tweak in the future”. It all adds up, and at a dangerous rate.

The road to programming hell is paved with “best practices” applied too early. Very few abstractions, extractions, or architectures are inherently bad (although I’ll contend that a few are). But most of them are downright evil if applied before they’re called for.

To take the scare quotes off flexibility, you have to be willing to write no code at all. The “Simplest Thing That Could Possibly Work” and “You’re Just Not Going To Need It” are both sayings to help you get there.

This really does mean not a single parameter to a method that has not yet found a use. No needless public methods that might get reused later (not even for testing!)

The hardest—and yet most important—thing in the world of design is the conviction to say no.