为什么这个$ class工作，$ this-> class不行？

Question

I have 2 classes

class A {

   // Do some stuff here!

}

and

class B {

   public $class = 'A';

   public function getClass(){

      //Case 1
      $class = $this->class;
      return new $class(); //work

      //Case 2
      return new $this->class(); //NOT work
      //or to be precise something like this
      return new {$this->class}(); 

   }

   // Do some other stuff here!

}

Why passing the class property to a var work and accessing directly NOT, like you see in the class above, Case 1 vs. Case 2 ?

Answer 1

The reason is

$class = $this->class;
return new $class();

Here $class will contain the value "A". So it will get class "A" when you call new $class()

But in

return new $this->class();

It will search for a function class() inside the class "B". So it will not work.

$this is for represent the current class instance. $this -> something() will always check for a function something() in the same class