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Date: Thu, 15 May 2025 21:56:30 +0200
To: =?UTF-8?Q?Tim_D=C3=BCsterhus?= <tim@bastelstu.be>
Cc: "Stephen Reay" <php-lists@koalephant.com>,
 "Andreas Hennings" <andreas@dqxtech.net>,
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 "Matthew Weier O'Phinney" <mweierophinney@gmail.com>,
 "php internals" <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] Clone with v2
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From: rob@bottled.codes ("Rob Landers")

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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 ensu=
re=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 able=
 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 t=
he=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 the=
 clone, it may register various states to ensure the patches are accurat=
e from that point. That's just one example, though, and it suggests call=
ing __clone *before* setting the values is the right answer.

I think Larry's idea of just using hooks for validation is also pretty g=
ood. As Larry said, the only thing you can really do is throw an excepti=
on, and the same would be true in a constructor as well.

=E2=80=94 Rob
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<!DOCTYPE html><html><head><title></title></head><body><div><br></div><d=
iv><br></div><div>On Thu, May 15, 2025, at 17:32, Tim D=C3=BCsterhus wro=
te:</div><blockquote type=3D"cite" id=3D"qt" style=3D""><div>Hi</div><di=
v><br></div><div>Am 2025-05-15 14:14, schrieb Rob Landers:</div><div>&gt=
; For example, if you have a Money type, you'd want to be able to ensure=
&nbsp;</div><div>&gt; it cannot be negative when updating via `with()`. =
This is super&nbsp;</div><div>&gt; important for ensuring constraints ar=
e met during the clone.</div><div><br></div><div>That's why the assignme=
nts during cloning work exactly like regular&nbsp;</div><div>property as=
signments, observing visibility and property hooks.</div><div><br></div>=
<div>The only tiny difference is that an =E2=80=9Coutsider=E2=80=9D is a=
ble to change a&nbsp;</div><div>`public(set) readonly` property after a =
`__clone()` method ran to&nbsp;</div><div>completion and relied on the p=
roperty in question not changing on the&nbsp;</div><div>cloned object af=
ter it observed its value. This seems not to be&nbsp;</div><div>somethin=
g relevant in practice, because why would the exact value of the&nbsp;</=
div><div>property only matter during cloning, but not at any other time?=
</div><div><br></div><div>Best regards</div><div>Tim D=C3=BCsterhus</div=
><div><br></div></blockquote><div><br></div><div>Hey Tim,</div><div><br>=
</div><blockquote type=3D"cite" id=3D"qt" style=3D""><div>why would the =
exact value of the&nbsp;</div><div>property only matter during cloning, =
but not at any other time?</div></blockquote><div><br></div><div>For exa=
mple, 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 __c=
lone&nbsp;<b>before</b> setting the values is the right answer.</div><di=
v><br></div><div>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=
.</div><div><br></div><div id=3D"sig121229152">=E2=80=94 Rob</div></body=
></html>
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