[ARROW-4567] [C++] Convert Scalar values to Array values with length 1

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Component/s: C++
• External issue URL: https://github.com/apache/arrow/issues/21113
• Assignee: Unassigned
• Reporter: Wes McKinney
• Created: 14/Feb/19 07:00
• Updated: 11/Jan/23 07:34
• Resolved: 14/May/20 01:53

Description

A common approach to performing operations on both scalar and array values is to treat a Scalar as an array of length 1. For example, we cannot currently use our Cast kernels to cast a Scalar. It would be senseless to create separate kernel implementations specialized for a single value, and much easier to promote a scalar to an Array, execute the kernel, then unbox the result back into a Scalar