From: "Dan0042 (Daniel DeLorme)" Date: 2022-01-30T21:43:07+00:00 Subject: [ruby-core:107368] [Ruby master Feature#18368] Range#step semantics for non-Numeric ranges Issue #18368 has been updated by Dan0042 (Daniel DeLorme). @zverok if understand correctly, the implication is that `range.step(1)` (using `+`) would have different semantics than `range.each` (using `succ`); I have reservations about that. Also, due to backward compatibility I don't think it's possible to change the behavior of `("a".."z").step(3)` so the simple rule of "it just uses +" would suffer from at least one special case. zverok (Victor Shepelev) wrote in #note-5: > What about other, non-core classes? Will we have implicitly defined `Object#increment` to handle them, and if so, how it is defined? Or each and every library should define their own `#increment`, and if it doesn't, the range iteration just fails? The idea is that `#increment` is used for addition but not concatenation. Nothing implicit. If a class has #increment defined that would be used for #step, otherwise it would fall back to using #succ, otherwise it would fail with "can't iterate" just like it does currently. Well, it's just one idea. From the dev meeting notes I also like nobu's idea of just delegating to `begin_object#upto`. ---------------------------------------- Feature #18368: Range#step semantics for non-Numeric ranges https://bugs.ruby-lang.org/issues/18368#change-96269 * Author: zverok (Victor Shepelev) * Status: Open * Priority: Normal ---------------------------------------- I am sorry if the question had already been discussed, can't find the relevant topic. "Intuitively", this looks (for me) like a meaningful statement: ```ruby (Time.parse('2021-12-01')..Time.parse('2021-12-24')).step(1.day).to_a # ^^^^^ or just 24*60*60 ``` Unfortunately, it doesn't work with "TypeError (can't iterate from Time)". Initially it looked like a bug for me, but after digging a bit into code/docs, I understood that `Range#step` has an odd semantics of "advance the begin N times with `#succ`, and yield the result", with N being always integer: ```ruby ('a'..'z').step(3).first(5) # => ["a", "d", "g", "j", "m"] ``` The fact that semantic is "odd" is confirmed by the fact that for Float it is redefined to do what I "intuitively" expected: ```ruby (1.0..7.0).step(0.3).first(5) # => [1.0, 1.3, 1.6, 1.9, 2.2] ``` (Like with [`Range#===` some time ago](https://bugs.ruby-lang.org/issues/14575), I believe that to be a strong proof of the wrong generic semantics, if for numbers the semantics needed to be redefined completely.) Another thing to note is that "skip N elements" seem to be rather "generically Enumerable-related" yet it isn't defined on `Enumerable` (because nobody needs this semantics, typically!) Hence, two questions: * Can we redefine generic `Range#step` to new semantics (of using `begin + step` iteratively)? It is hard to imagine the amount of actual usage of the old behavior (with String?.. to what end?) in the wild * If the answer is "no", can we define a new method with new semantics, like, IDK, `Range#over(span)`? -- https://bugs.ruby-lang.org/ Unsubscribe: