method chaining in php class

Question

I want to understand what is the difference between these chaining method

$obj->prop_a()->prob_b($y);

and

$obj->prop_a->prob_b($x);

how to define it and how it works.

Thanks in advance

Answer 1

On

$obj->prop_a()->prob_b($y);

you access prop_a() as a function . It return (obviously) an object, which implements an prob_b()-function.

On

$obj->prop_a->prob_b($x);

you access prop_a as a public property which contains an object, which again implements an prob_b() function.

Answer 2

一个调用prop_a作为方法，另一个不调用。

Answer 3

This:

class A {
  public function prop_b($x) {
    return 4*$x;
  }
}

class B {
  public function prop_a() {
    $a = new A();
    return $a;
  }
}

class C {
  public $prop_a;
  public function __construct() {
    $this->prop_a = new A();
  }
}

$b = new B();
$c = new C();
$b->prop_a()->prob_b(5);
$c->prop_a->prop_b(5);