Formatting Test
[email protected] (Nick Sdot) Sat, 11 Jul 2026 15:06:59 +0700
| Newsgroups | php.test |
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FORMATTING TEST
Hey Larry,
On 11.07.26 06:02, Larry Garfield wrote:
> On Sat, Jul 4, 2026, at 5:03 AM, Nick Sdot wrote:
>> Hey Internals,
>>
>> 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
> I had been planning to say "meh, doesn't seem like it would hurt anything," but as Tim pointed out with unserialize, it potentially could hurt something. That makes me skeptical.
>
> I also want to call out, as the RFC notes, that this is already a solved problem with private(set). It's not quite the same as readonly, but for most practical purposes it's close enough and already addresses the use case this RFC.
Thanks for the feedback.
I have to push back. It is not a solved problem. In fact, `private(set)`
is *not* only "not quite the same". Both features solve fundamentally
different problems -- `private(set)` has a foot gun `readonly` does not
have.
Because this point comes up repeatedly here is a concrete example:
```
<?php declare(strict_types=1);
final class PipelineOne // private(set)
{
public private(set)array $orderedPipelineSteps = [
\Thing\StepDoSomethingTwo::class,
\Thing\StepAtReportBeginning::class,
\Thing\StepDoSomethingOne::class,
];public function describe(): array {\sort($this->orderedPipelineSteps);// whoopsie, should have copied first $ordered = $this->orderedPipelineSteps;
// do stuff return $ordered;
}
}
final readonly class PipelineTwo// readonly{
public function __construct(public array $orderedPipelineSteps = [
\Thing\StepDoSomethingTwo::class,
\Thing\StepAtReportBeginning::class,
\Thing\StepDoSomethingOne::class,
],
) {}public function describe(): array {\sort($this->orderedPipelineSteps);// whoopsie, should have copied first $ordered = $this->orderedPipelineSteps;
// do stuff return $ordered;
}
}
// ###################### private(set) ###################### $one = new
PipelineOne();
\var_dump($one->describe());
// array(3) { // [0]=> // string(27) "Thing\StepAtReportBeginning" //
good, now ordered // [1]=> // string(24) "Thing\StepDoSomethingOne" //
[2]=> // string(24) "Thing\StepDoSomethingTwo" //} \var_dump($one->orderedPipelineSteps);
// array(3) { // [0]=> // string(27) "Thing\StepAtReportBeginning" //
whoopsie, this should NOT be first! // [1]=> // string(24)
"Thing\StepDoSomethingOne" // [2]=> // string(24)
"Thing\StepDoSomethingTwo" //} // ###################### readonly
###################### $two = new PipelineTwo();
\var_dump($two->describe());
//Fatal error: Uncaught Error: Cannot indirectly modify readonly
property PipelineTwo::$orderedPipelineSteps
```
With `private(set)` accidental mutation is legal. With `readonly`,
modification after initialisation is illegal. Both are great and useful
features, but `private(set)` only controls visibility not mutation. As
the above example proves, `readonly` is strict when it comes to mutation
and would have prevented the bug while `private(set)` happily ignores it
because mutation happens from within the class. With `readonly` it would
have been surfaced that I did:
```
<?php
\sort($this->orderedPipelineSteps); // whoopsie, mutated
$ordered = $this->orderedPipelineSteps;
```
instead of:
```
<?php
$ordered = $this->orderedPipelineSteps;
\sort($ordered);
```
This alone is reason enough to use `readonly` over `private(set)`; less
verbosity is a cherry on top.
Note: only to make the example copy & work without the PR branch I used
constructor property promotion here. With the RFC, `PipelineTwo`
can declare the property default directly, without allowing outside
modification.
--
Cheers
Nick
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<p> </p>
<div class="moz-text-html" lang="x-unicode">FORMATTING TEST
<div class="moz-text-html" lang="x-unicode">
<p>Hey Larry, </p>
<div class="moz-cite-prefix">On 11.07.26 06:02, Larry Garfield
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:[email protected]">
<pre wrap="" class="moz-quote-pre">On Sat, Jul 4, 2026, at 5:03 AM, Nick Sdot wrote:
</pre>
<blockquote type="cite">
<pre wrap="" class="moz-quote-pre">Hey Internals,
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:
<a class="moz-txt-link-freetext"
href="https://wiki.php.net/rfc/readonly_property_defaults">https://wiki.php.net/rfc/readonly_property_defaults</a>
</pre>
</blockquote>
<pre wrap="" class="moz-quote-pre">I had been planning to say "meh, doesn't seem like it would hurt anything," but as Tim pointed out with unserialize, it potentially could hurt something. That makes me skeptical.
I also want to call out, as the RFC notes, that this is already a solved problem with private(set). It's not quite the same as readonly, but for most practical purposes it's close enough and already addresses the use case this RFC.</pre>
</blockquote>
<p><br>
Thanks for the feedback.</p>
<p>I have to push back. It is not a solved problem. In fact,
`private(set)` is *not* only "not quite the same". Both
features solve fundamentally different problems
-- `private(set)` has a foot gun `readonly` does not have.</p>
<p>Because this point comes up repeatedly here is a concrete
example:</p>
<p>```<br>
</p>
<div style="background-color:#ffffff;color:#cb4247">
<pre
style="font-family:'JetBrains Mono',monospace;font-size:12,0pt;"><span
style="color:#4f5b93;"><?php
</span><span style="color:#4f5b93;">
</span><span style="color:#d73a49;">declare</span>(<span
style="color:#e36209;">strict_types</span><span
style="color:#b31d28;">=</span><span style="color:#005cc5;">1</span>);
</pre>
</div>
<p><br>
<span style="color:#d73a49;">final class </span><span
style="color:#808080;">PipelineOne // private(set)</span></p>
<div style="background-color:#ffffff;color:#cb4247">
<div style="background-color:#ffffff;color:#cb4247">
<pre
style="font-family:'JetBrains Mono',monospace;font-size:12,0pt;">{
<span style="color:#d73a49;">public private</span>(<span
style="color:#e36209;">set</span>) <span
style="color:#d73a49;">array </span><span
style="color:#808080;">$orderedPipelineSteps </span><span
style="color:#b31d28;">= </span>[
<span style="color:#808080;">\Thing\</span><span
style="color:#e36209;">StepDoSomethingTwo</span><span
style="color:#b31d28;">::</span><span style="color:#d73a49;">class</span>,
<span style="color:#808080;">\Thing\</span><span
style="color:#e36209;">StepAtReportBeginning</span><span
style="color:#b31d28;">::</span><span style="color:#d73a49;">class</span>,
<span style="color:#808080;">\Thing\</span><span
style="color:#e36209;">StepDoSomethingOne</span><span
style="color:#b31d28;">::</span><span style="color:#d73a49;">class</span>,
];<span style="color:#969896;">
</span><span style="color:#969896;">
</span><span style="color:#969896;"> </span><span
style="color:#d73a49;">public function </span><span
style="color:#6f42c1;">describe</span>()<span
style="color:#b31d28;">: </span><span style="color:#d73a49;">array
</span><span style="color:#d73a49;"> </span>{<span
style="color:#969896;">
</span><span style="color:#969896;"> </span>\<span
style="color:#6f42c1;">sort</span>(<span
style="color:#000000;">$this</span><span
style="color:#b31d28;">-></span><span
style="color:#005cc5;">orderedPipelineSteps</span>); <span
style="color:#969896;">// whoopsie, should have copied first
</span><span style="color:#969896;">
</span><span style="color:#969896;"> </span><span
style="color:#000000;">$ordered </span><span
style="color:#b31d28;">= </span><span style="color:#000000;">$this</span><span
style="color:#b31d28;">-></span><span
style="color:#005cc5;">orderedPipelineSteps</span>;
<span style="color:#969896;">// do stuff
</span><span style="color:#969896;">
</span><span style="color:#969896;"> </span><span
style="color:#d73a49;">return </span><span
style="color:#000000;">$ordered</span>;
}
}
<span style="color:#d73a49;">final readonly class </span><span
style="color:#808080;">PipelineTwo</span><span
style="color:#969896;"> // readonly</span><span
style="color:#808080;">
</span>{
<span style="color:#d73a49;">public function </span><span
style="color:#6f42c1;">__construct</span>(<span
style="color:#969896;">
</span><span style="color:#969896;"> </span><span
style="color:#d73a49;">public</span> <span
style="color:#d73a49;">array </span><span
style="color:#000000;">$orderedPipelineSteps </span><span
style="color:#b31d28;">= </span>[
<span style="color:#808080;">\Thing\</span><span
style="color:#e36209;">StepDoSomethingTwo</span><span
style="color:#b31d28;">::</span><span style="color:#d73a49;">class</span>,
<span style="color:#808080;">\Thing\</span><span
style="color:#e36209;">StepAtReportBeginning</span><span
style="color:#b31d28;">::</span><span style="color:#d73a49;">class</span>,
<span style="color:#808080;">\Thing\</span><span
style="color:#e36209;">StepDoSomethingOne</span><span
style="color:#b31d28;">::</span><span style="color:#d73a49;">class</span>,
],
) {}<span style="color:#969896;">
</span><span style="color:#969896;">
</span><span style="color:#969896;"> </span><span
style="color:#d73a49;">public function </span><span
style="color:#6f42c1;">describe</span>()<span
style="color:#b31d28;">: </span><span style="color:#d73a49;">array
</span><span style="color:#d73a49;"> </span>{<span
style="color:#969896;">
</span><span style="color:#969896;"> </span>\<span
style="color:#6f42c1;">sort</span>(<span
style="color:#000000;">$this</span><span
style="color:#b31d28;">-></span><span
style="color:#005cc5;">orderedPipelineSteps</span>); <span
style="color:#969896;">// whoopsie, should have copied first
</span><span style="color:#969896;">
</span><span style="color:#969896;"> </span><span
style="color:#000000;">$ordered </span><span
style="color:#b31d28;">= </span><span style="color:#000000;">$this</span><span
style="color:#b31d28;">-></span><span
style="color:#005cc5;">orderedPipelineSteps</span>;
<span style="color:#969896;">// do stuff
</span><span style="color:#969896;">
</span><span style="color:#969896;"> </span><span
style="color:#d73a49;">return </span><span
style="color:#000000;">$ordered</span>;
}
}
<span style="color:#969896;">// ###################### private(set) ######################
</span><span style="color:#000000;">$one </span><span
style="color:#b31d28;">= </span><span style="color:#d73a49;">new </span><span
style="color:#e36209;">PipelineOne</span>();
\<span style="color:#6f42c1;">var_dump</span>(<span
style="color:#000000;">$one</span><span
style="color:#b31d28;">-></span><span
style="color:#6f42c1;">describe</span>());
<span style="color:#969896;">// array(3) {
</span><span style="color:#969896;">// [0]=>
</span><span style="color:#969896;">// string(27) "Thing\StepAtReportBeginning" // good, now ordered
</span><span style="color:#969896;">// [1]=>
</span><span style="color:#969896;">// string(24) "Thing\StepDoSomethingOne"
</span><span style="color:#969896;">// [2]=>
</span><span style="color:#969896;">// string(24) "Thing\StepDoSomethingTwo"
</span><span style="color:#969896;">//}
</span>\<span style="color:#6f42c1;">var_dump</span>(<span
style="color:#000000;">$one</span><span
style="color:#b31d28;">-></span><span
style="color:#005cc5;">orderedPipelineSteps</span>);
<span style="color:#969896;">// array(3) {
</span><span style="color:#969896;">// [0]=>
</span><span style="color:#969896;">// string(27) "Thing\StepAtReportBeginning" // whoopsie, this should NOT be first!
</span><span style="color:#969896;">// [1]=>
</span><span style="color:#969896;">// string(24) "Thing\StepDoSomethingOne"
</span><span style="color:#969896;">// [2]=>
</span><span style="color:#969896;">// string(24) "Thing\StepDoSomethingTwo"
</span><span style="color:#969896;">//}
</span><span style="color:#969896;">// ###################### readonly ######################
</span><span style="color:#000000;">$two </span><span
style="color:#b31d28;">= </span><span style="color:#d73a49;">new </span><span
style="color:#e36209;">PipelineTwo</span>();
\<span style="color:#6f42c1;">var_dump</span>(<span
style="color:#000000;">$two</span><span
style="color:#b31d28;">-></span><span
style="color:#6f42c1;">describe</span>());
<span style="color:#969896;">//Fatal error: Uncaught Error: Cannot indirectly modify readonly property PipelineTwo::$orderedPipelineSteps</span></pre>
</div>
</div>
<p>```</p>
<p>With `private(set)` accidental mutation is legal. With
`readonly`, modification after initialisation is illegal. Both
are great and useful features, but `private(set)` only
controls visibility not mutation. As the above example proves,
`readonly` is strict when it comes to mutation and would have
prevented the bug while `private(set)` happily ignores it
because mutation happens from within the class. With
`readonly` it would have been surfaced that I did:</p>
<p>```<br>
</p>
<pre
style="font-family:'JetBrains Mono',monospace;font-size:12,0pt;"><span
style="color:#4f5b93;"><?php
</span>
</pre>
<p> \<span style="color:#6f42c1;">sort</span>(<span
style="color:#000000;">$this</span><span
style="color:#b31d28;">-></span><span
style="color:#005cc5;">orderedPipelineSteps</span>); <span
style="color:#969896;">// whoopsie, mutated</span><span
style="color:#000000;"><br>
</span></p>
<p><span style="color:#000000;">$ordered <span
style="color:#b31d28;">= <span style="color:#000000;">$this<span
style="color:#b31d28;">-><span
style="color:#005cc5;">orderedPipelineSteps;<br>
</span></span></span></span></span>```<br>
<br>
instead of:</p>
<p>```<br>
</p>
<pre
style="font-family:'JetBrains Mono',monospace;font-size:12,0pt;"><span
style="color:#4f5b93;"><?php
</span>
</pre>
<p><span style="color:#000000;">$ordered </span><span
style="color:#b31d28;">= </span><span
style="color:#000000;">$this</span><span
style="color:#b31d28;">-></span><span
style="color:#005cc5;">orderedPipelineSteps</span>;</p>
<div style="background-color:#ffffff;color:#cb4247">
<pre
style="font-family:'JetBrains Mono',monospace;font-size:12,0pt;">\<span
style="color:#6f42c1;">sort</span>(<span
style="color:#000000;">$ordered</span>);</pre>
</div>
<p>```</p>
<p>This alone is reason enough to use `readonly` over
`private(set)`; less verbosity is a cherry on top.</p>
<p>Note: only to make the example copy & work without the PR
branch I used constructor property promotion here. <span>With
the RFC, `PipelineTwo` can</span><span> declare the property
default directly, without allowing outside modification.</span></p>
<p>--</p>
<p>Cheers<br>
Nick</p>
</div>
</div>
<p><br>
</p>
</body>
</html>
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