On Thu, May 15, 2025, at 17:32, Tim Düsterhus wrote: > Hi > > Am 2025-05-15 14:14, schrieb Rob Landers: > > For example, if you have a Money type, you'd want to be able to ensure > > it cannot be negative when updating via `with()`. This is super > > important for ensuring constraints are met during the clone. > > That's why the assignments during cloning work exactly like regular > property assignments, observing visibility and property hooks. > > The only tiny difference is that an “outsider” is able to change a > `public(set) readonly` property after a `__clone()` method ran to > completion and relied on the property in question not changing on the > cloned object after it observed its value. This seems not to be > something relevant in practice, because why would the exact value of the > property only matter during cloning, but not at any other time? > > Best regards > Tim Düsterhus >
Hey Tim, > why would the exact value of the > property only matter during cloning, but not at any other time? For example, queueing up patches to store/db to commit later; during the clone, it may register various states to ensure the patches are accurate from that point. That's just one example, though, and it suggests calling __clone *before* setting the values is the right answer. I think Larry's idea of just using hooks for validation is also pretty good. As Larry said, the only thing you can really do is throw an exception, and the same would be true in a constructor as well. — Rob
