What is the difference between __CLASS__ and get_called_class?

Question

In PHP, I know two methods to display the name of the current class being called: through the magic constant __CLASS__ and function get_called_class().

Apparently, they both do the same thing.

class A 
{
     public static function className()
     { 
          echo get_called_class();
     }  
}


class B
{
     public static function className()
     { 
          echo __CLASS__;
     }  
}


B::className(); // 'B'
A::className(); // 'A'

There is a difference in performance between them?

Is there any difference when calling them?

Answer 1

Doing the tests after seeing this answer on Soen, they have different effects in situations when we extend a class:

• get_called_class returns the name of the current class and not where it was declared:

  <?php
  class Foo
  {
      static public function digaMeuNome()
      {
          var_dump(get_called_class());
      }
  }
  
  class Bar extends Foo
  {
  }
  
  Foo::digaMeuNome(); // Retorna Foo
  Bar::digaMeuNome(); // Retorna Bar
  

• __CLASS__ returns the name of the class where the method was declared, i.e. digaMeuNome was declared in Foo:

  <?php
  class Foo
  {
      static public function digaMeuNome()
      {
          var_dump(__CLASS__);
      }
  }
  
  class Bar extends Foo
  {
  }
  
  Foo::digaMeuNome(); // Retorna Foo
  Bar::digaMeuNome(); // Retorna Foo