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Date: Sun, 08 Jun 2025 21:15:19 +0200
To: "Volker Dusch" <volker@tideways-gmbh.com>,
 "php internals" <internals@lists.php.net>,
 =?UTF-8?Q?Tim_D=C3=BCsterhus?= <tim@bastelstu.be>
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 <CAMzRQTcN0VpQ_Ap_3WokH+aXp+EuSs=j=FLAL-43-0XgzgNtjg@mail.gmail.com>
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Subject: Re: [PHP-DEV] [VOTE] Clone with v2
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From: rob@bottled.codes ("Rob Landers")

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On Wed, Jun 4, 2025, at 17:13, Volker Dusch wrote:
> Hi everyone,
>=20
> We just opened the vote for the "Clone with v2" RFC:
>=20
> RFC: https://wiki.php.net/rfc/clone_with_v2
> Discussion: https://externals.io/message/127353
> PR: https://github.com/php/php-src/pull/18747
>=20
> As with every RFC, a 2/3 majority is required.
> Voting ends 2025-06-18 at 15:30:00 UTC.
>=20
> Kind regards,
> Volker
>=20
> --
> Volker Dusch
> Head of Engineering
> Tideways GmbH
> K=C3=B6nigswinterer Str. 116
> 53227 Bonn
> https://tideways.io/imprint
>=20
> Sitz der Gesellschaft: Bonn
> Gesch=C3=A4ftsf=C3=BChrer: Benjamin Au=C3=9Fenhofer (geb. Eberlei)
> Registergericht: Amtsgericht Bonn, HRB 22127

I=E2=80=99m just now getting around to really digging into the RFC, and =
I=E2=80=99m trying to understand what problems it is solving.

"withers" as they=E2=80=99re often called in other languages that use "w=
ith()" and this seems to implement, are most useful in cases of value/im=
mutable objects. In PHP, this usually looks something like this:

readonly class Money {
  private function __clone() {
    throw new LogicException("do not clone");
  }
  public function __construct(public int $pennies) {}
  public function with(int $pennies) { return new self($pennies); }
}

$dollar =3D new Money(100);
$quarter =3D $dollar->with(pennies: 25);

This is an overly simple example; where we want to make sure we have a s=
ingle "dollar" that would be equal to another "dollar". This implementat=
ion of clone() seems like it would be quite useful here, but it appears =
that setting __clone() to private would completely make this new clone()=
 break.

So, it seems like this can only be used for things that can already be c=
loned? Things which are directly trying to block an identical clone, but=
 would otherwise be fine with a clone that changes the value (e.g. value=
 objects) aren=E2=80=99t allowed to use this new feature?

To me, that feels like an oversight in the design.

=E2=80=94 Rob
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<!DOCTYPE html><html><head><title></title></head><body><div>On Wed, Jun =
4, 2025, at 17:13, Volker Dusch wrote:</div><blockquote type=3D"cite" id=
=3D"qt" style=3D""><div dir=3D"ltr"><div><div>Hi everyone,</div><div><br=
></div><div>We just opened the vote for the "Clone with v2" RFC:</div><d=
iv><br></div><div>RFC: <a href=3D"https://wiki.php.net/rfc/clone_with_v2=
">https://wiki.php.net/rfc/clone_with_v2</a></div><div>Discussion:&nbsp;=
<a href=3D"https://externals.io/message/127353">https://externals.io/mes=
sage/127353</a></div><div>PR:&nbsp;<a href=3D"https://github.com/php/php=
-src/pull/18747">https://github.com/php/php-src/pull/18747</a></div></di=
v><div><div><br></div><div>As with every RFC, a 2/3 majority is required=
.</div></div><div><div>Voting ends 2025-06-18 at 15:30:00 UTC.</div><div=
><br></div><div>Kind regards,</div></div><div>Volker</div><div><br></div=
><div><span class=3D"qt-gmail_signature_prefix">--</span></div><div dir=3D=
"ltr" class=3D"qt-gmail_signature"><div dir=3D"ltr"><div style=3D"color:=
rgb(34, 34, 34);font-family:arial, sans-serif;font-size:12.8px;">Volker =
Dusch</div><div style=3D"color:rgb(34, 34, 34);font-family:arial, sans-s=
erif;font-size:12.8px;">Head of Engineering</div><div style=3D"color:rgb=
(34, 34, 34);font-family:arial, sans-serif;font-size:12.8px;"><div>Tidew=
ays GmbH</div><div>K=C3=B6nigswinterer Str. 116</div><div>53227 Bonn</di=
v><div><a href=3D"https://tideways.io/imprint" style=3D"color:rgb(17, 85=
, 204);" target=3D"_blank">https://tideways.io/imprint</a></div><div><br=
></div><div>Sitz der Gesellschaft: Bonn</div><div>Gesch=C3=A4ftsf=C3=BCh=
rer: Benjamin Au=C3=9Fenhofer (geb. Eberlei)</div><div>Registergericht: =
Amtsgericht Bonn, HRB 22127</div></div></div></div></div></blockquote><d=
iv><br></div><div>I=E2=80=99m just now getting around to really digging =
into the RFC, and I=E2=80=99m trying to understand what problems it is s=
olving.</div><div><br></div><div>"withers" as they=E2=80=99re often call=
ed in other languages that use "with()" and this seems to implement, are=
 most useful in cases of value/immutable objects. In PHP, this usually l=
ooks something like this:</div><div><br></div><div>readonly class Money =
{</div><div>&nbsp; private function __clone() {</div><div>&nbsp; &nbsp; =
throw new LogicException("do not clone");</div><div>&nbsp; }</div><div>&=
nbsp; public function __construct(public int $pennies) {}</div><div>&nbs=
p; public function with(int $pennies) { return new self($pennies); }</di=
v><div>}</div><div><br></div><div>$dollar =3D new Money(100);</div><div>=
$quarter =3D $dollar-&gt;with(pennies: 25);</div><div><br></div><div>Thi=
s is an overly simple example; where we want to make sure we have a sing=
le "dollar" that would be equal to another "dollar". This implementation=
 of clone() seems like it would be quite useful here, but it appears tha=
t setting __clone() to private would completely make this new clone() br=
eak.</div><div><br></div><div>So, it seems like this can only be used fo=
r things that can already be cloned? Things which are directly trying to=
 block an identical clone, but would otherwise be fine with a clone that=
 changes the value (e.g. value objects) aren=E2=80=99t allowed to use th=
is new feature?</div><div><br></div><div>To me, that feels like an overs=
ight in the design.</div><div><br></div><div id=3D"sig121229152">=E2=80=94=
 Rob</div></body></html>
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