PHP property as object

Question

Is it possible to set a property of a class as a object?

Like:

class User {

    public $x = \"\";
    public $y = new ErrorVO();
    public $w = new         


        

Answer 1

Just my preferred solution, even if the others already explain everything: Injection

class A {
  public $a;
  public function __construct (ErrorVO $a) {
    $this->a = $a;
  }
}

This keeps the class testable and allows to replace the wanted ErrorVO-implementation very easy. Of course you can combine both solutions into one

class A {
  public $a;
  public function __construct (ErrorVO $a = null) {
    $this->a = is_null($a) ? new ErrorVO : $a;
  }
}

Minor Update: In the meantime you can write the second example like this

class A {
  public $a;
  public function __construct (ErrorVO $a = null) {
    $this->a = $a ?: new ErrorVO;
  }
}

It's slightly more compact and imo it makes the intention more clear. Compare the ?:-operator with MySQLs COALESCE