C++ 包裝器模式 boost庫實現

包裝器模式，又叫裝飾者模式，英文叫Decorator Pattern。裝飾模式是在不必改變原類文件和使用繼承的情況下，動態地擴展一個對象的功能。它是通過創建一個包裝對象，也就是裝飾來包裹真實的對象。

#include <iostream>
#include <boost/type_traits.hpp>
using namespace std;

class Myclass
{
public:
	Myclass() {};
	Myclass(int val): data(val) {}
	~Myclass() = default;
	void echo()
	{
		cout << data << endl;
	}

private:
	int data = 0;
};

template<typename T>
class Mywrapper
{
public:
	typedef typename ::boost::remove_pointer<T>::type wrapped_type;
	typedef wrapped_type* pointer_type;
	typedef wrapped_type& reference_type;

private:
	pointer_type m_ptr = nullptr;

protected:
	Mywrapper(pointer_type p):m_ptr(p){}
	Mywrapper(reference_type x):m_ptr(&x){}
	~Mywrapper() = default;

public:
	pointer_type get() const
	{
		return m_ptr;
	}
	
};

class Class final: public Mywrapper<Myclass>
{
public:
	typedef Mywrapper<Myclass> super_type;
	typedef Class this_type;
	
	Class(Myclass &m): super_type(m) {}
	~Class() = default;
};


int main()
{
	Myclass myclass(100);
	Class class1(myclass);
	class1.get()->echo();

	return 0;
}

 編譯：

g++ -o test test.cpp -std=c++11 -I /usr/local/include/boost