PrivateSetAndReadonlyNotTheSame.php

<?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