From: shevegen@... Date: 2020-03-07T10:42:23+00:00 Subject: [ruby-core:97400] [Ruby master Misc#16678] Array#values_at has unintuitive behavior when supplied a range starting with negative index Issue #16678 has been updated by shevegen (Robert A. Heiler). Actually .values_at() confused me when I tried to use my go-to method for obtaining a slice from an Array: a[3..5] # => [4, 5] There I wondered why it did not return the same. :-) But anyway; I believe the question is what -1 refers to. It should be the last entry, right? Ok, so what should the 3 indicate? I think you reason that it should refer to the fourth entry (I think ... if an Array count begins at 0, then 3 would refer to the fourth entry). So from that point of view I actually do not even disagree with you; perhaps I may have missed some other explanation. (There is probably another explanation; I think this has come up in the past too. I forgot the explanation, though, if there was one.) Personally I will stick with [] an leave .values_at() to others. I am just so used to [] there. ;-) ---------------------------------------- Misc #16678: Array#values_at has unintuitive behavior when supplied a range starting with negative index https://bugs.ruby-lang.org/issues/16678#change-84530 * Author: prajjwal (Prajjwal Singh) * Status: Open * Priority: Normal ---------------------------------------- Consider the following: ``` ruby # frozen_string_literal: true a = (1..5).to_a p a.values_at(3..5) # => [4, 5, nil] p a.values_at(-1..3) # => [] ``` When the range begins with a negative `(-1, 0, 1, 2, 3)`, it returns an empty array, which surprised me because I was expecting `[1, 2, 3, 4]`. The argument for this is that it cold be confusing to allow this because the index `-1` could refer to the last argument and it would be unintuitive to return an array `[5, 1, 2, 3, 4]` with jumbled values. The argument against it is that it makes perfect sense to account for this case and return `[nil, 1, 2, 3, 4]`. Opening a dialog to see what others think of this. -- https://bugs.ruby-lang.org/ Unsubscribe: