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Date: Wed, 24 Jul 2024 22:45:44 +0200
Message-ID: <CAOWwgp=apEVtNTr-3_oT1ndTTCuKmkvhsctn7QNqWVKPuZuqVg@mail.gmail.com>
Subject: Re: [PHP-DEV] [RFC] Lazy Objects
To: Rob Landers <rob@bottled.codes>
Cc: php internals <internals@lists.php.net>
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From: nicolas.grekas+php@gmail.com (Nicolas Grekas)

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Le mer. 24 juil. 2024 =C3=A0 21:44, Rob Landers <rob@bottled.codes> a =C3=
=A9crit :

>
>
> On Wed, Jul 24, 2024, at 16:28, Nicolas Grekas wrote:
>
>
> To Rob: proxying by interface can be implemented using regular code
> generation so it's not a blocker. Symfony does it already, and will
> continue to do it to cover the use case.
>
>
> I'm not sure what you mean, as the RFC makes it look this should be
> completely legal, until you get to the end:
>
> interface Fancy {
>   function sayHi(): void;
> }
> class A implements Fancy {
>   function sayHi(): void { echo "hi!"; }
> }
>
> $container->register(proxyType: Fancy::class, factory: fn() =3D> new A())=
;
>
> // Now container only knows that it needs to return a FancyClass and this
> is "legal looking":
>
> $lazy =3D new ReflectionClass($proxyType)->newLazyProxy($factory);
> // same as
> $lazy =3D new ReflectionClass(Fancy::class)->newLazyProxy(fn() =3D> new A=
());
>
> This ^ compiles, it's perfectly legal and makes 100% sense that I should
> be able to call $lazy->sayHi() and it calls A::sayHi(), which is what you
> would expect. Instead, this is runtime error.
>

The reason why this doesn't work is that the RFC is about state proxies,
which means properties are required to hook the lazy behavior.
The RFC forbids your snippet because the initializer must return a parent
of Fancy::class, which A::class isn't.

Please have a closer read of the RFC, we tried to describe the reasoning as
much as possible and this is covered.

Nicolas

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<div dir=3D"auto"><div><br><br><div class=3D"gmail_quote"><div dir=3D"ltr" =
class=3D"gmail_attr">Le mer. 24 juil. 2024 =C3=A0 21:44, Rob Landers &lt;ro=
b@bottled.codes&gt; a =C3=A9crit=C2=A0:<br></div><blockquote class=3D"gmail=
_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:=
1ex"><u></u><div><div><br></div><div><br></div><div>On Wed, Jul 24, 2024, a=
t 16:28, Nicolas Grekas wrote:<br></div><blockquote type=3D"cite" id=3D"m_3=
612589975186624774qt"><div dir=3D"ltr"><div dir=3D"ltr"><br></div><div><div=
>To Rob: proxying by interface can be implemented using regular code genera=
tion so it&#39;s not a blocker. Symfony does it already, and will continue =
to do it to cover the use case.<br></div></div></div></blockquote><div><br>=
</div><div>I&#39;m not sure what you mean, as the RFC makes it look this sh=
ould be completely legal, until you get to the end:<br></div><div><br></div=
><div>interface Fancy {<br></div><div>=C2=A0 function sayHi(): void;</div><=
div>}<br></div><div>class A implements Fancy {<br></div><div>=C2=A0 functio=
n sayHi(): void { echo &quot;hi!&quot;; }</div><div>}<br></div><div><br></d=
iv><div>$container-&gt;register(proxyType: Fancy::class, factory: fn() =3D&=
gt; new A());<br></div><div><br></div><div>// Now container only knows that=
 it needs to return a FancyClass and this is &quot;legal looking&quot;:<br>=
</div><div><br></div><div>$lazy =3D new ReflectionClass($proxyType)-&gt;new=
LazyProxy($factory);</div><div>// same as</div><div>$lazy =3D new Reflectio=
nClass(Fancy::class)-&gt;newLazyProxy(fn() =3D&gt; new A());<br></div><div>=
<br></div><div>This ^ compiles, it&#39;s perfectly legal and makes 100% sen=
se that I should be able to call $lazy-&gt;sayHi() and it calls A::sayHi(),=
 which is what you would expect. Instead, this is runtime error.</div></div=
></blockquote></div></div><div dir=3D"auto"><br></div><div dir=3D"auto">The=
 reason why this doesn&#39;t work is that the RFC is about state proxies, w=
hich means properties are required to hook the lazy behavior.</div><div dir=
=3D"auto">The RFC forbids your snippet because the initializer must return =
a parent of Fancy::class, which A::class isn&#39;t.</div><div dir=3D"auto">=
<br></div><div dir=3D"auto">Please have a closer read of the RFC, we tried =
to describe the reasoning as much as possible and this is covered.</div><di=
v dir=3D"auto"><br></div><div dir=3D"auto">Nicolas=C2=A0=C2=A0</div><div di=
r=3D"auto"></div></div>

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