类封装：如何准备添加新类的代码？

I have the following code:

我有以下代码：

class FooType1 : public FooInterface, public BarInterface1 {}
class FooType2 : public FooInterface, public BarInterface2 {}
class FooType3 : public FooInterface, public BarInterface3 {}

FooInterface service1 = boost::shared_ptr<FooType1>(new FooType1());
FooInterface service2 = boost::shared_ptr<FooType2>(new FooType2());
FooInterface service3 = boost::shared_ptr<FooType3>(new FooType3());

new Host(service1, service2, service3);

Host::Host(boost::shared_ptr<BarInterface1> service1, 
           boost::shared_ptr<BarInterface2> service2,
           boost::shared_ptr<BarInterface3> service3) {
    obj1 = service1;
    obj2 = service2;
    obj3 = service3;
}
class Fo