too long

Question

Is it possible to cast a parent class to its child in PHP? If not, what is the most efficient alternative to effecting this?

For example, the following results in an error:

<?php
class Foo {
    public $test;
    public static function create(): self {
        $a = new self();
        $a->test = 123;
        return $a;
    }
}

class Bar extends Foo {
    public $baz;
    public static function create(): self {
        $b = (self) parent::create(); // <--- Is this possible?
        $b->baz = 456;
        return $b;
    }
}

$bar = Bar::create();

var_dump($bar); /* should output:
  object(Bar)[35]
    public 'baz' => int 456
    public 'test' => int 123 */

Answer 1

I was able to implement this using the following strategy:

class Foo {
    public $test;
    public static function create(array $row): self {
        $a = new static();
        $a->test = $row['Test'];
        return $a;
    }
}

class Bar extends Foo {
    public $baz;
    public static function create(array $row): Foo {
        $b = parent::create($row);
        $b->baz = $row['Baz'];
        return $b;
    }
}

$test = Bar::create([
    'Test' => 123,
    'Baz' => 456,
]);

var_dump($test);
/* Outputs:
    object(Bar)#2 (2) {
        ["baz"]=> int(456)
        ["test"]=> int(123)
    } */