3 ms·

> my instinct is to reach for regexp captures, the solution it came up with is probably a lot faster and easier to read and avoids "now you have two problems”.

> my instinct is to reach for regexp captures, the solution it came up with is probably a lot faster and easier to read and avoids "now you have two problems”. I don’t write Rust but I think it’s best to trust your instinct here. “Now you have two problems” is a humorous quip and not practical coding advice. Using a regular expression to strip trailing digits from a string will surely result in code that is shorter and more readable than the alternatives, and it will probably be more correct too.

lamontcg 4y ago
You might be entirely correct. I noticed a small perf issue with the backwards scanning and had it rewrite it not using rfind("_"). First time I prompted it, though, it didn't actually manage to fix the problem and gave me some mild gaslighting until I told it to explicitly remove the rfind() call. Now I think the result should be comparable to or beat a regexp, but it is getting quite a bit more complex: fn strip_suffix(s: &str) -> String { let mut idx = s.len(); for (i, c) in s.char_indices().rev() { if c == '_' { idx = i; break; } else if !c.is_ascii_digit() { return s.to_string(); } } if idx == s.len() { return s.to_string(); } if s[idx+1..].chars().all(|c| c.is_ascii_digit()) { return s[..idx].to_string(); } s.to_string() } .char_indexes().rev() there worries me a bit as well now that I look at it... haven't tested that at all.
- lamontcg 4y ago
  Ah, it looks like char_indexes() implements DoubleEndedIterator and you can only call rev() on an iterator that does implement it, so that's fine.
- textninja 4y ago
  It took some coaching to get it to use the terse style I prefer, but here’s what 3.5 came up with in a conversation where I first asked about Rust’s support for regular expressions: use regex::Regex; fn strip_suffix_digits(s: &str) -> &str { let re = Regex::new(r"_\d+$").unwrap(); re.replace(s, "").as_ref() } As someone who does not program in Rust I find that quite readable, though I haven’t run it and can’t comment on how it compares outside of LOC. It does depend on the regex crate though.
  - lamontcg 4y ago
    Yeah I got basically the same sort of result out of it by asking for a Regexp, much shorter.

lamontcg 4y ago

You might be entirely correct. I noticed a small perf issue with the backwards scanning and had it rewrite it not using rfind("_"). First time I prompted it, though, it didn't actually manage to fix the problem and gave me some mild gaslighting until I told it to explicitly remove the rfind() call. Now I think the result should be comparable to or beat a regexp, but it is getting quite a bit more complex: fn strip_suffix(s: &str) -> String { let mut idx = s.len(); for (i, c) in s.char_indices().rev() { if c == '_' { idx = i; break; } else if !c.is_ascii_digit() { return s.to_string(); } } if idx == s.len() { return s.to_string(); } if s[idx+1..].chars().all(|c| c.is_ascii_digit()) { return s[..idx].to_string(); } s.to_string() } .char_indexes().rev() there worries me a bit as well now that I look at it... haven't tested that at all.

lamontcg 4y ago
Ah, it looks like char_indexes() implements DoubleEndedIterator and you can only call rev() on an iterator that does implement it, so that's fine.
textninja 4y ago
It took some coaching to get it to use the terse style I prefer, but here’s what 3.5 came up with in a conversation where I first asked about Rust’s support for regular expressions: use regex::Regex; fn strip_suffix_digits(s: &str) -> &str { let re = Regex::new(r"_\d+$").unwrap(); re.replace(s, "").as_ref() } As someone who does not program in Rust I find that quite readable, though I haven’t run it and can’t comment on how it compares outside of LOC. It does depend on the regex crate though.
- lamontcg 4y ago
  Yeah I got basically the same sort of result out of it by asking for a Regexp, much shorter.