2w ago

Learning to program in rust

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The weird part of rust is replacing straight forward semicolons from other languages with the more verbose .unwrap();.
Just kidding, don't lecture me about it.
- ?
  
  Exactly
  
  expr
  
  But then someone will have to deal with it somewhere, better just unwrap it under the carpet.
- The amount of people on the internet seriously complaining that both Rust error handling sucks and that .unwrap(); is too verbose is just staggering.
  
  I think the problem is that many introductory examples use unwrap, so many beginner programmers don’t get exposed to alternatives like unwrap_or and the likes.
  
  Yeah, we onboarded some folks into a Rust project last year and a few months in, they were genuinely surprised when I told them that unwrapping is pretty bad. Granted, they probably did read about it at some point and just forgot, but that isn't helped by lots of code using .unwrap() either.
  
  I’ll be honest, when I was learning to program in Java I mostly just wrapped errors in an empty try catch to shut them up, with no regard for actually handling them.
  I assume most other learners do that too.
  
  Java requiring you to write every exception that can happen in your code isn't helpful.
  Explicit error types are great, but Java managed to make them on a way where you get almost none of the upside and is so full of downsides that indoctrinated a generation into thinking knowing your errors is bad.
  
  I will say this: for me, learning rust was 80% un-learning habits from other languages.
  People tend to not like it when they have to change habits, especially if those took a long (and painful) time to acquire.
  In this particular case, this is the same complaint Go faced with its form of explicit error handling. And Java, for that matter.
  Honestly, Rust does a killer job of avoiding checked exceptions and verbose error hooks by way of the ? operator, and requiring all possible match branches to be accounted for. If you embrace errors fully, by using Result<> and custom Error types, your program gets a massive boost in robustness for not a lot of fuss. I recently learned that it gets even better if you embrace enum as a way to define error values, and make sure it implements useful traits like From and Display. With that, error handling code gets a lot more succinct, permitting one to more easily sift through different error values after a call (should you need to). All of that capability far exceeds any perception of clunkyness, IMO.
- Me, every time I try searching a Rust question.
  That's easy. Just do:
  rust
  
  fn is_second_num_positive() -> bool { let input = "123,-45"; let is_positive = input.split(',') .collect::<Vec<&str>>() .last() .unwrap() .parse::<i32>() .unwrap() .is_positive(); is_positive }
  
  Can't resist pointing out how you should actually write the function in a "real" scenario (but still not handling errors properly), in case anyone wants to know.
  If the list is guaranteed to have exactly two elements:
  rust
  
  fn is_second_num_positive_exact(input: &str) -> bool { let (_, n) = input.split_once(',').unwrap(); n.parse::<i32>().unwrap() > 0 }
  If you want to test the last element:
  rust
  
  fn is_last_num_positive(input: &str) -> bool { let n = input.split(',').next_back().unwrap(); n.parse::<i32>().unwrap() > 0 }
  If you want to test the 2nd (1-indexed) element:
  rust
  
  fn is_second_num_positive(input: &str) -> bool { let n = input.split(',').nth(1).unwrap(); n.parse::<i32>().unwrap() > 0 }
  
  Even better to use expect with a short message of what the assumption is: "the string should contain a comma" if it ever panics you'll know exactly why.
  
  Can still use .is_positive(), though...
- You can also use a shorter version .clone();

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