From: mail@... Date: 2016-06-07T09:23:05+00:00 Subject: [ruby-core:75871] [Ruby trunk Bug#12466] Enumerable should yield multiple values when possible Issue #12466 has been reported by Stefan Sch����ler. ---------------------------------------- Bug #12466: Enumerable should yield multiple values when possible https://bugs.ruby-lang.org/issues/12466 * Author: Stefan Sch����ler * Status: Open * Priority: Normal * Assignee: * ruby -v: 2.3.1 * Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN ---------------------------------------- Some methods in `Enumerable` and `Array` yield arrays instead of multiple values, e.g.: [1, 2, 3, 4].each_cons(2).peek_values #=> [[1, 2]] If `each_cons` would yield multiple values (i.e. `yield 1, 2` instead of `yield [1, 2]`), we could write: [1, 2, 3, 4].each_cons(2).map(&:quo) #=> [(1/2), (1/3), (1/4)] But currently, this results in an exception and we have to provide a block to achieve the above: [1, 2, 3, 4].each_cons(2).map { |a, b| a.quo(b) } #=> [(1/2), (2/3), (3/4)] No big deal, but it looks a bit cumbersome (in Ruby terms) and I don't see how the current behavior is preferable. Another example is `reverse_each` which cripples yielded values: def each_two_values return enum_for(__method__) unless block_given? yield 1, 2 yield 2, 3 yield 3, 4 end each_cons_values.map(&:quo) #=> [(1/2), (2/3), (3/4)] each_cons_values.reverse_each.map(&:quo) #=> NoMethodError: undefined method `quo' for [3, 4]:Array Of course, I can easily provide my own implementation: module Enumerable def my_reverse_each return enum_for(__method__) unless block_given? map { |*values| values }.reverse.each { |values| yield *values } end end each_cons_values.my_reverse_each.map(&:quo) #=> [(3/4), (2/3), (1/2)] But shouldn't this be the default behavior? If an array is actually needed (instead of multiple values), there's `Enumerable#each_entry` which performs the conversion. BTW, other methods _do_ yield multiple values: %w(a b c).each.with_index(1).peek_values #=> ["a", 1] -- https://bugs.ruby-lang.org/ Unsubscribe: