Possible Duplicate:
PHP: call to an instance method via ClassName::method syntax, results in a static call ?!

class A
{
   function foo()
   {
       if (isset($this)) {
           echo '$this is defined (';
           echo get_class($this);
           echo ")\n";
       } else {
           echo "\$this is not defined.\n";
       }
   }
}

A::foo();

Bu bir hata veya özellik var mı?