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Subject: Re: [PHP-DEV] [RFC] Readonly property hooks
Date: Sun, 13 Jul 2025 23:17:51 +0700
In-Reply-To: <ad11aaa7-b2a8-423c-a29c-4200789e9406@mabe.berlin>
Cc: internals@lists.php.net
To: Marc Bennewitz <marc@mabe.berlin>
References: <1e8634d7-ac1a-4025-b4e2-1948aabf5251@app.fastmail.com>
 <9D5043B2-1589-4FD5-B289-6E98FB1177BE@nicksdot.dev>
 <16BD443D-A179-465D-84A0-6E3780F62D8E@gmail.com>
 <203C1BD7-E688-4E26-8EA6-EA5331525470@nicksdot.dev>
 <ad11aaa7-b2a8-423c-a29c-4200789e9406@mabe.berlin>
From: php@nicksdot.dev (Nick)


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> On 13. Jul 2025, at 20:38, Marc Bennewitz <marc@mabe.berlin> wrote:
> Hi Nick, Claude,
Hey Marc,
> I think it's important to explicitly mark it as "this value will be =
stored in memory", I mean just silently caching the get hook could =
quickly lead to unexpected behavior. Like one would expect the value to =
be changed
>=20
The most here made the argument that "a changing value from a readonly =
get hook" would be the unexpected behaviour.=20
That=E2=80=99s why we ended up with the current =E2=80=9Calternative =
implementation 2=E2=80=9D. Please see my last answer to Rob for a fair =
example [1] .

The current preferred alternative implementation covers both =
situations...

If a property is `readonly`:=20
- you can set once
- on read you always get the same (once computed) value back

If a property is NOT `readonly`:
- you can set often
- on read you always get the fresh (often computed) value back

I argue that this is a very easy mental model.
I hope that voters agree on =E2=80=9Ccached may be implied by =
readonly=E2=80=9D, as Claude called it.

> and another one wonders why a big chunk of memory will not be freed =
`get =3D> $this->readBigFile();`.
>=20
Where do you see non-freed memory in one but not the other?=20

- in both scenarios, readonly or not, the `readBigFile()` will end up in =
memory.
- on each consecutive property call the usage in both scenarios is the =
same.
- when assigning a call the same property to multiple tmp vars the =
cached, once-computed version uses less memory than the non-cached =
version

Do I miss something? Did I misunderstand something?

Additionally, the cached version has the benefit that the expensive =
computation only happens once.
> On the one hand I like the cached modifier but personally I would =
prefer a separate init hook because it seems to be more clear that this =
is a backed property that will be initialized once.
>=20
To have an `init` hook doesn=E2=80=99t solve the get hook issue.
> The cached modifier I would expect to be an attribute applicable to =
any function which uses another cache store similar to how it's possible =
in python to memorize function calls which would be a very different =
feature.
>=20
As earlier answered to Claude [2], I seek to write less code. To =
introduce a `cached` modifier voids this for no strong reason (please =
see =E2=80=9Cmental model=E2=80=9D above).
=20
--

Cheers,
Nick

[1] https://news-web.php.net/php.internals/128010=20
[2] https://news-web.php.net/php.internals/128007


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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; =
charset=3Dutf-8"></head><body style=3D"overflow-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: =
after-white-space;"><br><div><blockquote type=3D"cite"><div>On 13. Jul =
2025, at 20:38, Marc Bennewitz &lt;marc@mabe.berlin&gt; =
wrote:</div></blockquote><blockquote type=3D"cite"><div><div><p>Hi Nick, =
Claude,<br>
    </p></div></div></blockquote>Hey Marc,<br><blockquote =
type=3D"cite"><blockquote type=3D"cite" =
cite=3D"mid:203C1BD7-E688-4E26-8EA6-EA5331525470@nicksdot.dev"><div></div>=
</blockquote><p></p></blockquote><blockquote type=3D"cite"><div><div><p>I =
think it's important to explicitly mark it as "this value will
      be stored in memory", I mean just silently caching the get hook
      could quickly lead to unexpected behavior. Like one would expect
      the value to be changed </p></div></div></blockquote><div><div>The =
most here made the argument that "a changing value from a readonly get =
hook" would be the unexpected behaviour.&nbsp;</div><div>That=E2=80=99s =
why we ended up with the current =E2=80=9Calternative implementation =
2=E2=80=9D. Please see my last answer to Rob for a fair example [1] =
.</div><div><br></div><div>The current preferred alternative =
implementation covers both =
situations...</div><div><br></div><div><div>If a property is =
`readonly`:&nbsp;</div><div>- you can set&nbsp;<b>once</b></div><div>- =
on read you always get the same (<u>once</u>&nbsp;computed) value =
back</div><div><br></div><div>If a property is NOT =
`readonly`:</div><div>- you can set&nbsp;<b>often</b></div><div>- on =
read you always get the fresh (<u>often</u>&nbsp;computed) value =
back</div></div><div><br></div><div>I argue that this is a very easy =
mental model.</div><div>I hope that voters agree on =E2=80=9C<code =
style=3D"color: rgb(51, 51, 51); font-size: 14px; orphans: 2; =
text-wrap-mode: wrap; widows: 2; background-color: rgb(242, 242, 242); =
box-sizing: border-box;">cached</code><span style=3D"color: rgb(51, 51, =
51); font-family: &quot;Fira Mono&quot;, monospace; font-size: 14px; =
orphans: 2; text-wrap-mode: wrap; widows: 2; background-color: rgb(242, =
242, 242);">&nbsp;may be implied by&nbsp;</span><code style=3D"color: =
rgb(51, 51, 51); font-size: 14px; orphans: 2; text-wrap-mode: wrap; =
widows: 2; background-color: rgb(242, 242, 242); box-sizing: =
border-box;">readonly</code>=E2=80=9D, as Claude called =
it.</div></div><div><br></div><blockquote type=3D"cite"><div><div><p>and =
another one wonders why a big chunk of
      memory will not be freed `get =3D&gt; =
$this-&gt;readBigFile();`.</p></div></div></blockquote><div>Where do you =
see non-freed memory in one but not the =
other?&nbsp;</div><div><br></div><div>- in both scenarios, readonly or =
not, the `readBigFile()` will end up in memory.</div><div>- on each =
consecutive property call the usage in both scenarios is the =
same.</div><div>- when assigning a call the same property to multiple =
tmp vars the cached, once-computed version uses less memory than the =
non-cached version</div><div><br></div><div>Do I miss something? Did I =
misunderstand something?</div><div><br></div><div>Additionally, the =
cached version has the benefit that the expensive computation only =
happens once.</div><blockquote type=3D"cite"><div><div><p>
    </p><p>On the one hand I like the cached modifier but personally I =
would
      prefer a separate init hook because it seems to be more clear that
      this is a backed property that will be initialized =
once.</p></div></div></blockquote><div>To have an `init` hook doesn=E2=80=99=
t solve the get hook issue.</div><blockquote type=3D"cite"><p>The cached =
modifier I would expect to be an attribute applicable
      to any function which uses another cache store similar to how it's
      possible in python to memorize function calls which would be a
      very different feature.</p></blockquote>As earlier answered to =
Claude [2], I seek to write less code. To introduce a `cached` modifier =
voids this for no strong reason (please see =E2=80=9Cmental model=E2=80=9D=
 =
above).</div><div>&nbsp;</div><div>--</div><div><br></div><div><b>Cheers,<=
/b></div><div>Nick</div><div><br></div><div>[1] =
https://news-web.php.net/php.internals/128010&nbsp;</div><div>[2] =
https://news-web.php.net/php.internals/128007</div><div><br></div></body><=
/html>=

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