小编Rob*_*wko的帖子

我正在使用外部库,需要创建一个观察者模式,其中观察者来自属于该库的对象.我不想从库中更改基类,同时我必须使用这个不可更改的基类的引用/指针列表.除此之外,库构造了对象列表,我需要从中筛选出适合观察者的对象.

我写的代码大致相当于:

#include <iostream>
#include <vector>
#include <memory>

// This class is from an external library which I don't want to chagne
class BaseFromLibrary {
  public:
    virtual ~BaseFromLibrary() {}
};

class BaseOfObserver {
  public:
    void notify() { std::cout << "What-ho!\n"; };
};

class Observer : public BaseFromLibrary, public BaseOfObserver {};

class Subject {
  public:
    std::vector<std::shared_ptr<Observer>> observers;
    void notifyObervers() {
        for (auto &o : observers)
            (*o).notify();
    }
};

int main() {
    // This list is constructed by the library and I …