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Date: Mon, 26 Jan 2026 18:49:52 +0100
Message-ID: <CAOWwgpnES5_b_T3-Zoko_+NzH2niJSDKz22sFkjYbk5vf=XiPQ@mail.gmail.com>
Subject: Re: [PHP-DEV] [RFC] Allow Reassignment of Promoted Readonly
 Properties in Constructor
To: Larry Garfield <larry@garfieldtech.com>
Cc: php internals <internals@lists.php.net>
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From: nicolas.grekas+php@gmail.com (Nicolas Grekas)

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Hi Larry,

Le dim. 25 janv. 2026 =C3=A0 19:53, Larry Garfield <larry@garfieldtech.com>=
 a
=C3=A9crit :

> On Sat, Jan 24, 2026, at 12:09 PM, Nicolas Grekas wrote:
>
> >> Boring is good in this case. :-)  I like the updates.  I only have two
> remaining quibbles.
> >>
> >> > All other readonly semantics remain unchanged (no modification
> outside constructor, no unsetting, etc.)
> >>
> >> As previously stated, "no modification outside constructor" is not, an=
d
> has never been, part of the language semantics of readonly.  In fact, the
> RFC has been updated now such that updates outside of the constructor are
> allowed, provide the constructor is in the call stack.  Please remove tha=
t
> clause, as it is incorrect.
> >
> > How would you phrase this?
> > To me, point 3 above makes this clear: "The reassignment must occur
> > while a constructor of the object is on the call stack (methods and
> > closures called from the constructor are allowed)"
> > Then, point 7: "All other readonly semantics remain unchanged (no
> > modification outside constructor, no unsetting, etc.)" has enough
> > context to me to be clear.
> >
> > No?
>
> There's a very subtle caveat here.  Readonly properties that are not yet
> initialized can be set from anywhere, not just the constructor.  That is
> the language semantic, regardless of what the PHPStan/Psalm authors think=
.
> :-)
>
> In this particular case, because the property is being set in the
> constructor preamble, essentially, it cannot then be re-assigned... EXCEP=
T
> in the constructor due to this RFC.  But that's a subtle, easy to miss
> caveat.  Hence why I'd prefer wording that doesn't imply (to those that
> don't catch that subtlety) that the language doesn't allow readonly to be
> assigned outside of the constructor.
>
> This is a particular pet peeve of mine because I have very good use cases
> for assigning to a readonly property outside of the constructor, but alwa=
ys
> therefore have to disable that check in PHPStan as a result.  Hence why I
> harp on it so much. :-)


 I updated the text to make this more clear, thanks for the suggestion!

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<div dir=3D"ltr"><div dir=3D"ltr">Hi Larry,</div><br><div class=3D"gmail_qu=
ote gmail_quote_container"><div dir=3D"ltr" class=3D"gmail_attr">Le=C2=A0di=
m. 25 janv. 2026 =C3=A0=C2=A019:53, Larry Garfield &lt;<a href=3D"mailto:la=
rry@garfieldtech.com">larry@garfieldtech.com</a>&gt; a =C3=A9crit=C2=A0:<br=
></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;=
border-left:1px solid rgb(204,204,204);padding-left:1ex">On Sat, Jan 24, 20=
26, at 12:09 PM, Nicolas Grekas wrote:<br>
<br>
&gt;&gt; Boring is good in this case. :-)=C2=A0 I like the updates.=C2=A0 I=
 only have two remaining quibbles.<br>
&gt;&gt; <br>
&gt;&gt; &gt; All other readonly semantics remain unchanged (no modificatio=
n outside constructor, no unsetting, etc.)<br>
&gt;&gt; <br>
&gt;&gt; As previously stated, &quot;no modification outside constructor&qu=
ot; is not, and has never been, part of the language semantics of readonly.=
=C2=A0 In fact, the RFC has been updated now such that updates outside of t=
he constructor are allowed, provide the constructor is in the call stack.=
=C2=A0 Please remove that clause, as it is incorrect.<br>
&gt;<br>
&gt; How would you phrase this?<br>
&gt; To me, point 3 above makes this clear: &quot;The reassignment must occ=
ur <br>
&gt; while a constructor of the object is on the call stack (methods and <b=
r>
&gt; closures called from the constructor are allowed)&quot;<br>
&gt; Then, point 7: &quot;All other readonly semantics remain unchanged (no=
 <br>
&gt; modification outside constructor, no unsetting, etc.)&quot; has enough=
 <br>
&gt; context to me to be clear.<br>
&gt;<br>
&gt; No?<br>
<br>
There&#39;s a very subtle caveat here.=C2=A0 Readonly properties that are n=
ot yet initialized can be set from anywhere, not just the constructor.=C2=
=A0 That is the language semantic, regardless of what the PHPStan/Psalm aut=
hors think. :-)<br>
<br>
In this particular case, because the property is being set in the construct=
or preamble, essentially, it cannot then be re-assigned... EXCEPT in the co=
nstructor due to this RFC.=C2=A0 But that&#39;s a subtle, easy to miss cave=
at.=C2=A0 Hence why I&#39;d prefer wording that doesn&#39;t imply (to those=
 that don&#39;t catch that subtlety) that the language doesn&#39;t allow re=
adonly to be assigned outside of the constructor.<br>
<br>
This is a particular pet peeve of mine because I have very good use cases f=
or assigning to a readonly property outside of the constructor, but always =
therefore have to disable that check in PHPStan as a result.=C2=A0 Hence wh=
y I harp on it so much. :-)</blockquote><div><br></div><div>=C2=A0I updated=
 the text to make this more clear, thanks for the suggestion!=C2=A0</div></=
div></div>

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