On the other hand, no abstractions is like reading a book where each and every thing is spelled out in outmost detail. Instead of telling you “I’m fuelling the car”, I’ll tell you: “I’m walking to the entrance hall. I’m picking up the car keys. I’m putting on my shoes. I’m putting on my jacket. I’m unlocking the front door ...”. You see where this is going. And here we already assumed that things like “putting on shoes” are provided by a standard library.

There seems to be two types of programmers: one that can read a line of code like or theCar.fuel() and trust that you in the current context understand enough of what the call does that you can continue reading on the current level of code. This type of programmers don’t mind abstractions even if a function is called in only one place.

The other type of programmer must immediately dig into the car.fuel code and make sure she understands that functionality before she can continue. And of course then each and every call becomes a misdirection from understanding the code, and of course for them it is better is everything is spelled out on the same level.

I’ve seen quite a bit of code written by the second type of programmers, and if you don’t mind scrolling and don’t mind reading the comment chapter headers (/* here we fuel the car */) instead of all the code itself, it can be reasonably readable. But there’s never comprehensive testing coverage for this kind of code, and there’s usually code for fuelling the car in four different places because programmers 2-4 didn’t have time to read all the old code to see if there was something they could reuse, and just assumed that no one had to fuel the car before since there wasn’t any car.fuel() method.