C++设计问题: Can i query the base classes to find the number of derived classes satisfying a condition

Question

我有一段这样的代码

class Base
{
public:
Base(bool _active)
{
 active = _active;
}
void Configure();
void Set Active(bool _active);
private: 
bool active;
};
class Derived1 : public Base
{
public:
Derived1(bool active):Base(active){}

};

similarly Derived 2 and Derived 3

现在，如果我调用 derived1Object.Configure，我需要检查有多少 derived1Obj、derived2Obj、derived3Obj 处于事件状态。我应该像函数 GetNumberOfActive() 那样在“基”类中添加它吗？

如果实现是这样的:

class Imp
{
public:
 void Configure()
 {
  //Code instantiating a particular Derived1/2/3 Object 
  int GetNumberOfActiveDerivedObj();
  baseRef.Configure(int numberOfActiveDerivedClasses);
 }
prive:
Derived1 dObj1(true);
Derived2 dObj2(false);
Derived3 dObj3(true);
};

我应该计算 Imp 类中的 numberOfActive 派生对象吗？

谢谢

Answer 1

一个简单的可能性:

NumberOfActive 在 Base 中应该是 static。每次创建对象并且 active 为真时，它都应该递增。