d::x PHP Method

    public function x()
    {
        $this->cpa1;
        $this->cpa2;
        $this->cpb1;
        $this->cpb2;
        $this->cpc11;
        $this->cpc21;
        $this->cpd1;
        $this->cpe1;
    }

 public static function foo()
 {
     $foo = new d();
     d::$x = $foo;
     unset($foo);
     echo "Foo: ";
     echo d::$x = "main";
     echo "\n";
     var_dump(d::$x);
 }