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