在PHP中初始化静态成员

Question

class Person {
  public static function ShowQualification() {
  }
}

class School {
  public static $Headmaster = new Person(); // NetBeans complains about this line
}

Why is this not possible?

I want to be able to use this like

School::Headmaster::ShowQualification();

..without instantiating any class. How can I do it?

Update: Okay I understood the WHY part. Can someone explain the HOW part? Thanks :)

Answer 1

From the docs,

"Like any other PHP static variable, static properties may only be initialized using a literal or constant; expressions are not allowed."

new Person() is not a literal or a constant, so this won't work.

You can use a work-around:

class School {
  public static $Headmaster;
}

School::$Headmaster = new Person();