Issue #17017 has been updated by marcandre (Marc-Andre Lafortune). jeremyevans0 (Jeremy Evans) wrote in #note-10: > With current Ruby, you should use an endless range instead of range with an infinite end. Endless ranges are 2.6+. Ruby 2.5 is not yet EOL. RuboCop supports 2.4 and other gems support earlier Rubies. More importantly, endless range max is currently not useful... Note even `(4.2..).max` and variations return an infinity. I should open an issue about this... > Note that if you use the exclusive range (`42...Float::INFINITY`), you would get a `TypeError` in 2.7.1, so it's not like we exclusively used `RangeError` for issues like these. I agree with you, `TypeError` is also wrong. > Mathematically, `42..Float::INFINITY` and `42...Float::INFINITY` represent the same range We'll have to disagree with this . I'm sure in some mathematical definition that it is the case, but in many others it is not. `42..Float::INFINITY` is not defined in traditional Euclidian space. On a Riemann sphere it is not the same as `42...Float::INFINITY`. If seen as sequences, you could see them as ¦Ø ("infinity") and ¦Ø - 1 which are distinct numbers (see surreal numbers), etc. > All that said, I'm not completely opposed to special casing `Float::INFINITY` in this case. Great. I hope we can make infinity handling useful. ---------------------------------------- Bug #17017: Range#max & Range#minmax incorrectly use Float end as max https://bugs.ruby-lang.org/issues/17017#change-86560 * Author: sambostock (Sam Bostock) * Status: Open * Priority: Normal * ruby -v: ruby 2.8.0dev (2020-07-14T04:19:55Z master e60cd14d85) [x86_64-darwin17] * Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN ---------------------------------------- While continuing to add edge cases to [`Range#minmax` specs](https://github.com/ruby/spec/pull/777), I discovered the following bug: ```ruby (1..3.1).to_a == [1, 2, 3] # As expected (1..3.1).to_a.max == 3 # As expected (1..3.1).to_a.minmax == [1, 3] # As expected (1..3.1).max == 3.1 # Should be 3, as above (1..3.1).minmax == [1, 3.1] # Should be [1, 3], as above ``` One way to detect this scenario might be to do (whatever the C equivalent is of) ```ruby range_end.is_a?(Numeric) // Is this a numeric range? && (range_end - range_begin).modulo(1) == 0 // Can we reach the range_end using the standard step size (1) ``` As for how to handle it, a couple options come to mind: - We could error out and do something similar to what we do for exclusive ranges ```ruby raise TypeError, 'cannot exclude non Integer end value' ``` - We might be able to calculate the range end by doing something like ```ruby num_steps = (range_end / range_beg).to_i - 1 # one fewer steps than would exceed the range_end max = range_beg + num_steps # take that many steps all at once ``` - We could delegate to `super` and enumerate the range to find the max ```ruby super ``` - We could update the documentation to define the max for this case as the `range_end`, similarly to how the documentation for `include?` says it behaves like `cover?` for numeric ranges. -- https://bugs.ruby-lang.org/ Unsubscribe: <mailto:ruby-core-request / ruby-lang.org?subject=unsubscribe> <http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>