Hi folks, I am seeking feedback on making a breaking change for the DGM chop method (just for an Iterator parameter) for Groovy 5. This wouldn't change chop for any of the other aggregate types (collections and arrays).
For our DGM methods on iterators, we have a bunch that are a little like stream intermediate operators which return iterators, and others which are more like terminal operators which return non-aggregate results or some kind of aggregate like a collection. The benefit of the ones which return iterators is that they are lazily evaluated (to vary degrees). You can chain a bunch of them together and intermediate calculations are done lazily, and intermediate collections aren't created unnecessarily, saving memory and time. Currently, chop is treated like a terminal operator (fully eager), returning a list of lists. I'd like to make this an iterator of lists (just when working on an iterator). This would make it align more closely with other operators (e.g. collate and others). I'd supply a bridge method with the existing signature, so code compiled with Groovy 4 and earlier using compile static would happily work without change. Is this really needed? Well, to some extent no. We can just call ".toIterator()" and continue chaining. There will just be one step that isn't as efficient as it could be. Is this the most efficient and lazy? Well, no, returning an iterator of iterators could be made more lazy. But the iterator of lists is the happy middle ground we have chosen for many other operators and that is what I'd like to move this to. We could always add a "chopLazy" or some such that return the iterator of iterators. And also consider collateLazy, etc. There is a PR here: https://github.com/apache/groovy/pull/2173 The implications: folks using this method (we don't believe it is widely used) would need to add ".toList()" if they needed the eager behavior. Folks wanting the chaining behavior would no longer need to add ".iterator()". Breaking changes are always disruptive but inconsistent APIs are also troublesome. We are seeking feedback on whether folks would be greatly impacted/amenable to this change. It would be added as a breaking change in the release notes. Thoughts? Thanks, Paul.
