A local variable is often worse: Now I suffer both the noise of the unabstracted thing, and an extra assignment. While part of the goal is to give a reasonable logical name to the complex business logic, the other value is to hide the business logic for readers who truly don't care (which is most of them).
The names could be better and more expressive, sure, but they could also be function calls themselves or long and difficult to read names, as an example:
That's somewhat realistic for cases where the abstraction is covering for business logic. Now if you're lucky you can abstract that away entirely to something like an injected feature or binary flag (but then you're actually doing what I'm suggesting, just with extra ceremony), but sometimes you can't for various reasons, and the same concept applies.
In fact I'd actually strongly disagree with you and say that doing what I'm suggesting is even more important if the example is larger and more complicated. That's not an excuse to not have tests or not maintain your code well, but if your argument is functionally "we cannot write abstractions because I can't trust that functions do what they say they do", that's not a problem with abstractions, that's a problem with the codebase.
I'm arguing that keeping the complexity of any given stanza of code low is important to long-term maintainability, and I think this is true because it invites a bunch of really good questions and naturally pushes back on some increases in complexity: if `is_enabled(x)` is the current state of things, there's a natural question asked, and inherent pushback to changing that to `is_enabled(x, y)`. That's good. Whereas its much easier for natural development of the god-function to result in 17 local variables with complex interrelations that are difficult to parse out and track.
My experience says that identifying, removing, and naming assumptions is vastly easier when any given function is small and tightly scoped and the abstractions you use to do so also naturally discourage other folks who develop on the same codebase from adding unnecessary complexity.
And I'll reiterate: my goal, at least, when dealing with abstraction isn't to focus on duplication, but on clarity. It's worthwhile to introduce an abstraction even for code used once if it improves clarity. It may not be worthwhile to introduce an abstraction for something used many times if those things aren't inherently related. That creates unnecessary coupling that you either undo or hack around later.
I'm speaking solely from a developer experience perspective.
We're talking about cases where the expression is only used once, so the assignment is free/can be trivially inlined, and the attribute lookups are also only used once so there is nothing saved by creating a temporary for them.
The names could be better and more expressive, sure, but they could also be function calls themselves or long and difficult to read names, as an example:
That's somewhat realistic for cases where the abstraction is covering for business logic. Now if you're lucky you can abstract that away entirely to something like an injected feature or binary flag (but then you're actually doing what I'm suggesting, just with extra ceremony), but sometimes you can't for various reasons, and the same concept applies.In fact I'd actually strongly disagree with you and say that doing what I'm suggesting is even more important if the example is larger and more complicated. That's not an excuse to not have tests or not maintain your code well, but if your argument is functionally "we cannot write abstractions because I can't trust that functions do what they say they do", that's not a problem with abstractions, that's a problem with the codebase.
I'm arguing that keeping the complexity of any given stanza of code low is important to long-term maintainability, and I think this is true because it invites a bunch of really good questions and naturally pushes back on some increases in complexity: if `is_enabled(x)` is the current state of things, there's a natural question asked, and inherent pushback to changing that to `is_enabled(x, y)`. That's good. Whereas its much easier for natural development of the god-function to result in 17 local variables with complex interrelations that are difficult to parse out and track.
My experience says that identifying, removing, and naming assumptions is vastly easier when any given function is small and tightly scoped and the abstractions you use to do so also naturally discourage other folks who develop on the same codebase from adding unnecessary complexity.
And I'll reiterate: my goal, at least, when dealing with abstraction isn't to focus on duplication, but on clarity. It's worthwhile to introduce an abstraction even for code used once if it improves clarity. It may not be worthwhile to introduce an abstraction for something used many times if those things aren't inherently related. That creates unnecessary coupling that you either undo or hack around later.