在静态方法中,是否有任何方法可以检测目标类?

下面是一个示例类层次结构和代码。我正在寻找一种方法来确定“childClass1”或“childClass2”是否在不在每个子类中重新实现的情况下调用了静态方法whoami()。

<?php

abstract class ParentClass {

    public static function whoAmI () {

        // NOT correct, always gives 'ParentClass'
        $class = __CLASS__;

        // NOT correct, always gives 'ParentClass'. 
        // Also very round-about and likely slow.
        $trace = debug_backtrace();
        $class = $trace[0]['class'];

        return $class;
    }
}

class ChildClass1 extends ParentClass {

}

class ChildClass2 extends ParentClass {

}

// Shows 'ParentClass'
// Want to show 'ChildClass1'
print ChildClass1::whoAmI(); 
print "\n";

// Shows 'ParentClass'
// Want to show 'ChildClass2'
print ChildClass2::whoAmI();
print "\n";