没怎么用过这个新特性，其实也不算新啦，试试吧，现在静态类的继承很方便了

<?php
class A {
 protected static $def = "123456";

 public static function test() {
  echo get_class(new static);
 }

 public static function test2() {
  echo static::$def;
 }
}

class B extends A {
 protected static $def = "456789";
}

class C extends A {
 protected static $def = "abcdef";
}

echo B::test();
echo "<br>";
echo C::test();
echo "<br>";
echo B::test2();
echo "<br>";
echo C::test2();
echo "<br>";
echo A::test();
echo "<br>";
echo A::test2();
echo "<br>";

// 输出结果
B
C
456789
abcdef
A
123456