Online PHP editor | output for JmkoK

<?php class SomeImmutableObject { private $someString; private $flagCreate = false; public function __construct(string $value) { if ($this->flagCreate === true) { throw new \BadMethodCallException('This immutable object has already been created.'); } $this->someString = $value; $this->flagCreate = true; } public function getValue(): string { return 'the value is:' . $this->someString . ' - '; } } class AnotherClassToBreakImmutableObject extends SomeImmutableObject { public function __construct(string $value) { $this->someString = $value; } public function getValue(): string { return 'the value is:' . $this->someString . ' - '; } public function change(): void { $this->someString .= ' and Baz'; } } $three = new AnotherClassToBreakImmutableObject('Foo'); echo $three->getValue(); //Foo echo $three->change(); echo $three->getValue(); //the value is: Foo and Baz -