PHP：我可以在_constructor中传递$ this吗？

Question

I would like to pass a php object in its own constructor to another object like this:

class foo {

 $parent_object;

 public function __construct($obj) {
  $this->parent_object = $obj;
  }
 }

class bar {

 public function __construct() {
  $blub = new foo($this);
  }
 }

The question I am asking myself is: Can I pass $this in the constructor of bar, because the object has not actually been created... so is $this already a valid reference to the whole object?

Answer 1

Sure you can. Keep in mind that $this always points to the current object though. So in:

$blub = new foo($this);

$this points to the instance of bar. So $obj in the constructor of foo is that instance of bar.

$this is available at the beginning of the constructor. Now if bar immediately calls functions on $obj it might be that the instance of bar is not yet in the right state (ie. $blub has not been assigned). This could lead to reference issues, the solution to that would be to move the reference exchange out of the constructor.