多态性是否值得增加耦合？

Question

我正在编写一个简单的游戏来学习获得更多的C++经验,我有一个想法,我觉得多态几乎可以工作,但没有.在这个游戏中,Party移动相当线性地通过一个Map,但偶尔可以Fork在路上遇到一个.fork(基本上)是一个std::vector<location*>.Originally我打算在Party成员函数中编写如下代码:

if(!CurrLocation->fork_.empty())
   // Loop through forks and show options to the player, go where s/he wants
else
  (CurrLocation++)

但我想知道以下某些变体是否会更好:

CurrLocation = CurrLocation->getNext();

使用Fork实际上是从Location派生的,并且重载了一些新功能getNext().但在后一种情况下,在location(低层次结构)将不得不提出的信息给用户,而不是"通过这个备份",我不觉得是优雅的,因为它夫妻一个location来UserInterface::*.

你的意见？

Answer 1

通过添加一个间接级别可以解决所有问题.我将使用您建议的变体,并通过允许getNext接受解析方向选择的对象来将Party与Party分离.这是一个例子(未经测试):

class Location; 

class IDirectionChooser
{
public:
  virtual bool ShouldIGoThisWay(Location & way) = 0;
};

class Location
{
public:
  virtual Location * GetNext(IDirectionChooser & chooser)
  {
    return nextLocation;
  }

  virtual Describe();
private:
  Location * nextLocation;
};

class Fork : public Location
{
public:
  virtual Location * GetNext(IDirectionChooser & chooser)
  {
    for (int i = 0; i < locations.size(); i++)
      if (chooser.ShouldIGoThisWay(*locations[i]))
        return locations[i];
  }
  virtual Describe();
private:
  vector<Location *> locations;
};

class Party : public IDirectionChooser
{
public:
  void Move()
  {
    currentLocation = currentLocation->GetNext(GetDirectionChooser());
  }

  virtual IDirectionChooser & GetDirectionChooser() { return *this; }

  virtual bool ShouldIGoThisWay(Location & way)
  {
    way.Describe();
    cout << "Do you want to go that way? y/n" << endl;

    char ans;
    cin >> ans;
    return ans == 'y';
  }
};