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<?php class Foo { public const DEFAULT_BAR = 5; public $bar = FOO::DEFAULT_BAR; public function bar(?int $bar = null): Foo { $this->bar = $bar ?? $this->bar; return $this; } static public function withBar(?int $bar = null): Foo { return (new self())->bar($bar ?? Foo::DEFAULT_BAR); } public function fromBar(?int $bar = null): Foo { return (new self())->bar($bar ?? $this->bar); } public function fork(): Foo { return clone $this; } } $a = Foo::withBar(); $b = Foo::withBar(4); $b2 = $b->fromBar(); $c = Foo::withBar(); var_dump( $a->bar, $b->bar, $b2->bar, $c->bar );