From: "matz (Yukihiro Matsumoto)" Date: 2013-06-05T09:15:27+09:00 Subject: [ruby-core:55308] [ruby-trunk - Feature #8490][Rejected] Bring ActiveSupport Enumerable#index_by to core Issue #8490 has been updated by matz (Yukihiro Matsumoto). Status changed from Open to Rejected I don't think "index" is a proper term here. Array#index, Enumerable#find_index, Enumerable#with_index all treat "index" as an offset to an item in the enumerables. Whereas this method (index_by) is not related to offsets. Matz. ---------------------------------------- Feature #8490: Bring ActiveSupport Enumerable#index_by to core https://bugs.ruby-lang.org/issues/8490#change-39704 Author: rosenfeld (Rodrigo Rosenfeld Rosas) Status: Rejected Priority: Normal Assignee: matz (Yukihiro Matsumoto) Category: core Target version: It seems to be a common sense to have the useful implementation of Enumerable#index_by as in ActiveSupport. index_by acts like group_by but only maps a single record, instead of an array, keeping the last match only. It's usually used in places where you shouldn't have more than a single match for each key. Would you consider its inclusion to core Enumerable module? -- http://bugs.ruby-lang.org/