@Incubating
public class CopyWithRecorder
extends GroovyObjectSupport

Recording delegate for the transactional copyWith { } block. It does not mutate anything: property assignments and prop.modify { } calls are recorded as a (possibly dotted) path-keyed map which is then handed to the nested-aware copyWith(Map) for reconstruction.

Reads of a property return a child recorder bound to the extended path, so address.city = 'NYC' records 'address.city'.

The reserved name old resolves to the original (root) object — aligning with the old of @Ensures/@Contract in design-by-contract — so a value may be derived from the pre-state: address.city = old.address.city.reverse() or, cross-field, name = old.company.name. The concise single-field shorthand address.city.modify { it.reverse() } remains for the common transform-this-same-field case.

On a navigated path the recorder intercepts modify, so a same-named real method on the value type is shadowed there. old is the escape hatch: past old the RHS is the real object, so a genuine modify(Closure) (or any other domain method) runs and its result is recorded — e.g. balance = old.balance.modify { it + 50 }. old may equally be preferred purely for style, when .modify on a path could be misread, even if no real method exists.

Since:

6.0.0