Issue #6118 has been updated by mame (Yusuke Endoh). Status changed from Open to Assigned Assignee set to matz (Yukihiro Matsumoto) ---------------------------------------- Feature #6118: Hash#keys_of(values), returns related keys of given values https://bugs.ruby-lang.org/issues/6118#change-25399 Author: naruse (Yui NARUSE) Status: Assigned Priority: Normal Assignee: matz (Yukihiro Matsumoto) Category: Target version: Hash#key(value) ??®è????°ç???????»ã???????§ã????? {a: 1, b: 2, c: 3, d: 1}.key(1) => :a ??¨ã???????¡ã?½ã???????¯ã???????®ã?§ã???????? {a: 1, b: 2, c: 3, d: 1}.keys_of(1) => [:a, :d] ??¨ã???????¡ã?½ã???????¯ç?¶ã???????¾ã???????? Ruby ??§ã?®å??è£?ä¾???¯ä»¥ä¸???®ã???????ªæ???????«ã?ªã????¾ã????? ??©ã????§ã?????????????? class Hash def keys_of(*a) each_with_object([]) {|(k, v), r| r << k if a.include? v} end end -- http://bugs.ruby-lang.org/