[ARROW-6299] [C++] Simplify FileFormat classes to singletons

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Won't Do
• Fix Version/s: 0.16.0
• Component/s: C++
• Labels: dataset
• External issue URL: https://github.com/apache/arrow/issues/22680
• Assignee: Ben Kietzman
• Reporter: Ben Kietzman
• Created: 20/Aug/19 13:32
• Updated: 11/Jan/23 07:46
• Resolved: 24/Oct/19 15:03

Description

ParquetFileFormat has no state, so passing it around by shared_ptr<FileFormat> is not necessary; we could just keep a single static instance and pass raw pointers.

wesmckinn is there a case where a FileFormat might have state?