PHP self, $this, const,static function

If the method of the class is static, the properties that he accesses must also be static.
, when the internal method of the class accesses properties that are not declared const and static, use $this->value = ' class_a ';
Class Clss_a {
private static $name = "Static Class_a";
Const pi=3.14;
Public $value;
public static function GetName ()
{
Return self:: $name;
}
This is incorrect, and static methods cannot access non-static properties
public static function GetName2 ()
{
Return self:: $value;
}
Public Function GETPI ()
{
Return self::P i;
}

}