class MyClass
{
  private static $MyMember = 99;

  public static function MyFunction()
  {
    echo self::$MyMember;
  }
}

MyClass::MyFunction();

请参阅可见性和范围解析运算符 (::) 在 php 手册的 oop5 章节中.

see Visibility and Scope Resolution Operator (::) in the oop5 chapter of the php manual.