我在 C++ 中实现了装饰器模式,如下所示:
#include <iostream>
#include <string>
#include <deque>
using namespace std;
// Abstract Component
template <class T>
class IArray
{
public:
virtual void insert(const T&) = 0;
virtual ~IArray(){}
};
// Concrete Component
template <class T>
class Array : public IArray<T>
{
public:
virtual void insert(const T& elem)
{
m_array.push_back(elem);
}
private:
deque<T> m_array;
};
// Decorator 1
template <class T>
class PositiveArray : public IArray<T>
{
public:
PositiveArray(IArray<T>* component):m_component(component)
{
}
virtual void insert(const T& elem)
{
if (elem > 0)
{
m_component->insert(elem);
}
else
{
cerr << "You can't insert non-positive number." <<endl;
}
}
private:
IArray<T>* m_component;
};
// Decorator 2
template <class T>
class PrintArray : public IArray<T>
{
public:
PrintArray(IArray<T>* component):m_component(component)
{
}
virtual void insert(const T& elem)
{
m_component->insert(elem);
cout << "Element " << elem << " was inserted into the array." <<endl;
}
private:
IArray<T>* m_component;
};
// Client
int main()
{
typedef int MyType;
PositiveArray<MyType> arr(new PrintArray<MyType>(new Array<MyType>));
arr.insert(10);
arr.insert(-10);
int i;
cin>>i;
return 0;
}
现在我想拥有所有数组printArray
功能。我应该将它写为 IArray 中的纯虚函数并在 IArray 的每个子项中复制该函数的以下实现吗?
void printArray()
{
for (int i = 0; i < m_array.size(); ++i)
{
cout << "elem " <<i << " is " << m_array[i] <<endl;
}
}
有没有可以避免复制的解决方案?