in which case I will go one level down, to the calculateExtraCommissions() method.
In which case you will discover that the calculateExtraCommissions() function also has the same nested functions and you eventually find six subfunctions that each calculate some fraction of the extra commission, all of which could have been condensed into three lines of code in the parent function.
Following the author’s idea of clean code to the letter results in a thick and incomprehensible function soup.
If there are 6 subfunctions, that means there’s 6 levels of abstraction (assuming the method extraction was not done blindly), which further suggests that maybe they should actually be part of a different class (or classes). Why would you be interested in 6 levels of abstraction at once?
But we’re arguing hypotheticals here. Of course you can make the method implementations a complete mess, the book cannot guarantee that the person applying the principles used their brain, as well.
Because abstractions leak. Heck, abstractions are practically lies most of the time.
What’s the most time-consuming thing in programming? Writing new features? No, that’s easy. It’s figuring out where a bug is in existing code.
How do abstractions help with that? Can you tell, from the symptoms, which “level of abstraction” contains the bug? Or do you need to read through all six (or however many) “levels”, across multiple modules and functions, to find the error? Far more commonly, it’s the latter.
And, arguably worse, program misbehavior is often due to unexpected interactions between components that appear to work in isolation. This means that there isn’t a single “level of abstraction” at which the bug manifests, and also that no amount of unit testing would have prevented the bug.
In which case you will discover that the calculateExtraCommissions() function also has the same nested functions and you eventually find six subfunctions that each calculate some fraction of the extra commission, all of which could have been condensed into three lines of code in the parent function.
Following the author’s idea of clean code to the letter results in a thick and incomprehensible function soup.
It’s only as incomprehensible as you make it.
If there are 6 subfunctions, that means there’s 6 levels of abstraction (assuming the method extraction was not done blindly), which further suggests that maybe they should actually be part of a different class (or classes). Why would you be interested in 6 levels of abstraction at once?
But we’re arguing hypotheticals here. Of course you can make the method implementations a complete mess, the book cannot guarantee that the person applying the principles used their brain, as well.
Because there aren’t 6 interesting levels of abstraction. It’s like talking to a child:
Because abstractions leak. Heck, abstractions are practically lies most of the time.
What’s the most time-consuming thing in programming? Writing new features? No, that’s easy. It’s figuring out where a bug is in existing code.
How do abstractions help with that? Can you tell, from the symptoms, which “level of abstraction” contains the bug? Or do you need to read through all six (or however many) “levels”, across multiple modules and functions, to find the error? Far more commonly, it’s the latter.
And, arguably worse, program misbehavior is often due to unexpected interactions between components that appear to work in isolation. This means that there isn’t a single “level of abstraction” at which the bug manifests, and also that no amount of unit testing would have prevented the bug.