Hi
Am 2025-06-04 14:19, schrieb Nick:
Fair. If someone really wants to add random_int(): "well, that
assumption doesn't hold anymore, deal” from my side.
Semantically once you involved inheritance it isn't that easy. It is
allowed to override an “unhooked” property with a hooked property and in
the “Readonly Amendments” RFC we already decided that inheriting from a
`readonly` class by a non-`readonly` class should not be valid.
So if you would be allowed to override a readonly unhooked property with
a hooked property that has a `get` hook that is not a pure function, you
would make the property effectively mutable, which is something that
users of the class can't expect. It violates the history property of the
Liskov substitution principle.
Making this legal might also inhibit engine optimization. Currently if
you know that a property is readonly you can theoretically optimize:
if ($object->foo !== null) {
do_something($object->foo);
}
into:
if (($foo = $object->foo) !== null) {
do_something($foo);
}
to avoid reading `$object->foo` twice, which for example would need to
check visibility twice.
I believe at the moment that RFC text is all there is. :-) I don't
know that it's worth opening a discussion without at least a
mostly-done implementation. Also, Ilija is rather busy on other tasks
at the moment, as am I. (Unless someone else wants to jump in to
implement it, which would be fine.)
People often say “you can just do things”. So I did, and tried to
contribute the code for your existing RFC text:
https://github.com/php/php-src/pull/18757
Can it really be such a little change? I’d appreciate feedback from
people more experienced than I am. Thanks!
Your test cases really only scratch the surface of what should be
tested. You are basically just verifying that it compiles. In fact you
are not even testing that reassigning the property is disallowed,
because the test fails due to a visibility error. In fact it appears
that the `readonly` check comes before the visibility check, which would
imply that the `readonly` doesn't have an effect: https://3v4l.org/nqgpL
Best regards
Tim Düsterhus
