[GROOVY-11253] Identity variants for DGM#countBy

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 5.0.0-alpha-4
• Assignee: Paul King
• Reporter: Paul King
• Created: 18/Dec/23 10:50
• Updated: 22/Dec/23 11:38
• Resolved: 18/Dec/23 23:34

Description

We haven't added such functionality in the past since it was thought to be more of a niche use case than groupBy (where we do provide it). But given this is the closest Groovy has to creating a multiset/bag, it is probably worth having as a shortcut - rather than requiring an explicit Closure.IDENTITY.

Whether Groovy should have specialised multiset and multimap classes is another question for another issue. We could use ".toMultiset()" to return a more specialised multiset return type in that case, so we aren't making it harder with this PR to add such functionality later if we wanted.

Issue Links

• relates to: GROOVY-10982 Provide missing identity closure CountBy variants
• links to: GitHub Pull Request #2016