From: "rosenfeld (Rodrigo Rosenfeld Rosas)" Date: 2013-06-06T00:18:55+09:00 Subject: [ruby-core:55322] [ruby-trunk - Feature #8490] Bring ActiveSupport Enumerable#index_by to core Issue #8490 has been updated by rosenfeld (Rodrigo Rosenfeld Rosas). I don't see any issues with index_by, but how about map_by? And what is wrong with the semantics? ---------------------------------------- Feature #8490: Bring ActiveSupport Enumerable#index_by to core https://bugs.ruby-lang.org/issues/8490#change-39727 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/