Re: [PHP-DEV] [RFC] Readonly Property Defaults

Hey Tim,

thanks for the feedback!

On 09.07.26 16:12, Tim Düsterhus wrote:
> Hi
>
> On 2026-07-04 12:03, Nick Sdot wrote:
>> I would like to present a tiny, five-line-removal RFC allowing 
>> default values on readonly properties.
>>
>> Allowing default values on readonly class properties enables creating 
>> a strict contract for implementation property values that will not 
>> change at runtime -- as in, constant-like behaviour with contract. I 
>> would love doing that.
>>
>> Please find the RFC text here: 
>> https://wiki.php.net/rfc/readonly_property_defaults
>
> Thank you, the proposal makes sense to me. I have just some requests 
> for clarification:
>
> 1.
>
> Can you add a “clone-with” example to the “Interaction with clone” 
> section? I assume that “clone-with” will also just work for the same 
> reasons, but it makes sense to spell it out.

Spelled it out and added a test for it.
>
> 2.
>
> Can you spell out the unserialization behavior with an example. 
> “Unserialisation continues to use the existing object hydration 
> semantics and is not changed by this RFC” is not clear to me, because 
> from my mental model unserialization first does a 
> `newInstanceWithoutConstructor()` and then fills in the properties 
> based on the serialized data. Thus a readonly field with a default 
> value would already be initialized, which means that filling in the 
> serialized data would fail, which I think is not a situation we have 
> so far.

At the time `__unserialize` is called the object exists, and the 
property is initialised with the default value. So it fails in the same 
way a re-assignment in the constructor or reflection `setValue()` will 
fail. So, I wouldn't say "not a situation we have so far", but agree 
that spelling it out cannot be wrong. RFC section is updated, and your 
PR comment example added as a test!
>
> 3.
>
> In the “Interaction with asymmetric visibility” section, the example 
> would be stronger with a `public(set)` instead of `private(set)`, 
> because with `private(set)` the example would fail either way, since 
> the global scope has no access to the property.
>

You are right. Changed.

> 4.
>
> Minor polishing remark in “Interaction with traits”: The opening PHP 
> tag is missing in the example.
>

Fixed!
> Best regards
> Tim Düsterhus

--

Cheers
Nick