Issue #11808 has been updated by noelrap (Noel Rappin). This appears to be fixed in 3.3.0dev as of Nov 2023, ``` ruby irb(main):001* class Test irb(main):002* include Enumerable irb(main):003* def each irb(main):004* return enum_for(:each) unless block_given? irb(main):005* yield "Hello" irb(main):006* yield "World" irb(main):007* end irb(main):008> end => :each irb(main):009> irb(main):010> enum = Test.new => #<Test:0x0000000102ba5038> irb(main):011> array = ["Hello", "World"] => ["Hello", "World"] irb(main):012> irb(main):013> enum.grep(/^(.)/) {$1} => ["H", "W"] ``` However, it was still broken in 3.2.2. It's not clear to me when the behavior changed. ---------------------------------------- Bug #11808: Different behavior between Enumerable#grep and Array#grep https://bugs.ruby-lang.org/issues/11808#change-105298 * Author: BenOlive (Ben Olive) * Status: Open * Priority: Normal * Assignee: ko1 (Koichi Sasada) * Backport: 2.5: UNKNOWN, 2.6: UNKNOWN ---------------------------------------- Regex special global variables are available within the block for `Array#grep`, but are nil within the block for `Enumerable#grep`. Here is an example that explains it better: ~~~ruby class Test include Enumerable def each return enum_for(:each) unless block_given? yield "Hello" yield "World" end end enum = Test.new array = ["Hello", "World"] enum.grep(/^(.)/) {$1} # => [nil, nil] array.grep(/^(.)/) {$1} # => ["H", "W"] ~~~ Tested on 2.0.0, 2.1.5, & 2.2.2 -- https://bugs.ruby-lang.org/