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Date: Tue, 24 Feb 2026 08:02:21 +0200
Message-ID: <CAAwdEzDpLNdKkvx6tQgufB-x-xKk+acNtsHhnDF3FM1JymqZxQ@mail.gmail.com>
Subject: Re: [PHP-DEV] [RFC] Readonly Variables
To: Kamil Tekiela <tekiela246@gmail.com>
Cc: =?UTF-8?Q?Joshua_R=C3=BCsweg?= <josh@wcflabs.de>, 
	PHP internals <internals@lists.php.net>
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From: drealecs@gmail.com (=?UTF-8?Q?Alexandru_P=C4=83tr=C4=83nescu?=)

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On Tue, 24 Feb 2026, 00:00 Kamil Tekiela, <tekiela246@gmail.com> wrote:

> On Mon, 23 Feb 2026 at 21:29, Joshua R=C3=BCsweg <josh@wcflabs.de> wrote:
> >
> > Hi internals,
> >
> > I'd like to propose a new language feature for PHP: Readonly Variables.
> >
> > PHP currently has no way to declare a variable as immutable within a
> local or functional scope. This RFC proposes the readonly modifier for
> variables, which prevents reassignment after the initial declaration and
> results in an error on any attempt to do so.
> >
> > The RFC is available at:
> > https://wiki.php.net/rfc/readonly-variables
> >
> > I'm looking forward to your feedback and discussion.
> >
> > Cheers,
> > Joshua R=C3=BCsweg
>
> Hi Joshua,
>
> This is a very interesting proposal, but I feel like you haven't
> explained all your choices. I have some questions:
>
> 1. Why the use of readonly keyword? Why not const or some new keyword,
> e.g. locked.
>
> I would prefer starting with readonly parameters as I feel that would
> bring the most value.
> I think it would also be worthwhile to investigate a simpler syntax
> for define().
>
>
Hi Kamil, Joshua,
I wrote on this topic in the past:
https://news-web.php.net/php.internals/126909
and I think we already cannot use readonly and final for parameter, as that
conflicts with constructor parameter promotion:
> if we ever decide to use the final modifier for a
parameter, it would not be possible.
> it is already not possible to use the readonly modifier for a parameter
because of this

I think that using const keyword might be one of the best options.

--=20
Alex

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<div dir=3D"auto"><div><br><br><div class=3D"gmail_quote gmail_quote_contai=
ner"><div dir=3D"ltr" class=3D"gmail_attr">On Tue, 24 Feb 2026, 00:00 Kamil=
 Tekiela, &lt;<a href=3D"mailto:tekiela246@gmail.com">tekiela246@gmail.com<=
/a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0=
 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Mon, 23 Feb 2026 =
at 21:29, Joshua R=C3=BCsweg &lt;<a href=3D"mailto:josh@wcflabs.de" target=
=3D"_blank" rel=3D"noreferrer">josh@wcflabs.de</a>&gt; wrote:<br>
&gt;<br>
&gt; Hi internals,<br>
&gt;<br>
&gt; I&#39;d like to propose a new language feature for PHP: Readonly Varia=
bles.<br>
&gt;<br>
&gt; PHP currently has no way to declare a variable as immutable within a l=
ocal or functional scope. This RFC proposes the readonly modifier for varia=
bles, which prevents reassignment after the initial declaration and results=
 in an error on any attempt to do so.<br>
&gt;<br>
&gt; The RFC is available at:<br>
&gt; <a href=3D"https://wiki.php.net/rfc/readonly-variables" rel=3D"norefer=
rer noreferrer" target=3D"_blank">https://wiki.php.net/rfc/readonly-variabl=
es</a><br>
&gt;<br>
&gt; I&#39;m looking forward to your feedback and discussion.<br>
&gt;<br>
&gt; Cheers,<br>
&gt; Joshua R=C3=BCsweg<br>
<br>
Hi Joshua,<br>
<br>
This is a very interesting proposal, but I feel like you haven&#39;t<br>
explained all your choices. I have some questions:<br>
<br>
1. Why the use of readonly keyword? Why not const or some new keyword,<br>
e.g. locked.<br><br>
I would prefer starting with readonly parameters as I feel that would<br>
bring the most value.<br>
I think it would also be worthwhile to investigate a simpler syntax<br>
for define().<br><br></blockquote></div></div><div dir=3D"auto"><br></div><=
div dir=3D"auto"></div><div dir=3D"auto">Hi Kamil, Joshua,</div><div dir=3D=
"auto">I wrote on this topic in the past:=C2=A0<a href=3D"https://news-web.=
php.net/php.internals/126909">https://news-web.php.net/php.internals/126909=
</a></div><div dir=3D"auto">and I think we already cannot use readonly and =
final for parameter, as that conflicts with constructor parameter promotion=
:</div><div dir=3D"auto">&gt; if we ever decide to use the final modifier f=
or a</div><div dir=3D"auto">parameter, it would not be possible.</div><div =
dir=3D"auto">&gt; it is already not possible to use the readonly modifier f=
or a parameter</div><div dir=3D"auto">because of this</div><div dir=3D"auto=
"><br></div><div dir=3D"auto">I think that using const keyword might be one=
 of the best options.</div><div dir=3D"auto"><br></div><div dir=3D"auto">--=
=C2=A0</div><div dir=3D"auto">Alex</div><div dir=3D"auto"><br></div><div di=
r=3D"auto"></div></div>

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