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Date: Thu, 15 May 2025 15:11:13 -0500
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Subject: Re: [PHP-DEV] [RFC] Clone with v2
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From: larry@garfieldtech.com ("Larry Garfield")

On Thu, May 15, 2025, at 2:56 PM, Rob Landers wrote:
> On Thu, May 15, 2025, at 17:32, Tim D=C3=BCsterhus wrote:
>> Hi
>>=20
>> Am 2025-05-15 14:14, schrieb Rob Landers:
>> > For example, if you have a Money type, you'd want to be able to ens=
ure=20
>> > it cannot be negative when updating via `with()`. This is super=20
>> > important for ensuring constraints are met during the clone.
>>=20
>> That's why the assignments during cloning work exactly like regular=20
>> property assignments, observing visibility and property hooks.
>>=20
>> The only tiny difference is that an =E2=80=9Coutsider=E2=80=9D is abl=
e to change a=20
>> `public(set) readonly` property after a `__clone()` method ran to=20
>> completion and relied on the property in question not changing on the=20
>> cloned object after it observed its value. This seems not to be=20
>> something relevant in practice, because why would the exact value of =
the=20
>> property only matter during cloning, but not at any other time?
>>=20
>> Best regards
>> Tim D=C3=BCsterhus
>>=20
>
> Hey Tim,
>
>> why would the exact value of the=20
>> property only matter during cloning, but not at any other time?
>
> For example, queueing up patches to store/db to commit later; during=20
> the clone, it may register various states to ensure the patches are=20
> accurate from that point. That's just one example, though, and it=20
> suggests calling __clone *before* setting the values is the right=20
> answer.
>
> I think Larry's idea of just using hooks for validation is also pretty=20
> good. As Larry said, the only thing you can really do is throw an=20
> exception, and the same would be true in a constructor as well.
>
> =E2=80=94 Rob

The limit of hooks is that they're single-property.  So depending on how=
 your derived properties are implemented, it may be insufficient.  I cou=
ld easily write such an example (the hooks RFC included some), but how c=
ontrived they are, I don't know.

--Larry Garfield