如何使用Reflection在运行时使用php扩展类

How can I use Reflection to extend a class in runtime?
I need A class is extended from B class.

class A{
    function methodA()
    {
        echo 'This is method A';
    }
}

class B{
    function methodB()
    {
        echo 'This is method B';
    }
}

You can't do it using reflection, but you could using runkit. I really, really wouldn't recommend doing it though; if a class should extend another class, make it so from the beginning.

You cannot. As the name suggests, Reflection is for reflection alone, gathering data about the code, and not modification.