I understand that the point of his example is to introduce the reader to a variant of the very classic multitier architecture with layers. https://en.wikipedia.org/wiki/Multitier_architecture But I prefer the first version of the example, because while it's named "complex code" I think it's the simplest version. I think that there is no need to decouple this simple and straightforward function in three functions that…
This reminds me of Brian Will's "Object-orientation is Bad" where he makes the case that most decoupling tends to be more confusing than long-form code that's got sufficient comments. https://youtu.be/QM1iUe6IofM?t=2235
fn x() {
doStuff();
moreStuff();
forgotSomething();
}
fn x(y) {
foo = doStuff(y);
bar = moreStuff(foo);
if (isSomething(bar)) {
return theRest(bar)
} else {
return theBest(bar);
}
}
It's important, however, that these helper functions are not haphazardly strewn around the code base and accessible to things that don't need them. Depending on the language/context, I'd reach for nested function definitions or public/private keywords (or a combination), because definitely, it can be very hard to approach a big file with a bunch of (often poorly-named) functions that are defined at the same hierarchical level but not meant to be used at the same level.