Issue #8811 has been reported by sawa (Tsuyoshi Sawada). ---------------------------------------- Feature #8811: Counterpart to `Hash#key?` for `Array` https://bugs.ruby-lang.org/issues/8811 Author: sawa (Tsuyoshi Sawada) Status: Open Priority: Normal Assignee: Category: Target version: =begin `Hash` hash `key?` to tell if a key exists without checking the value. It would be convenient if there were a counterpart in `Array`. Suppose it is called `Array#index?`. Then it should behave as follows: [1, 2, 3].index?(2) # => true [1, 2, 3].index?(3) # => false [1, 2, 3].index?(-3) # => true [1, 2, 3].index?(-4) # => false This is useful when we want to insert/move/delete elements to/from a certain position of an array. Without checking if a value exists, it can be messed up. Implementing a check is cumbersome now. With the proposed method, it would become easy. =end -- http://bugs.ruby-lang.org/