设计模板类，使得在创建一个对象时可以动态确定它的基类(public)

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
using namespace std;
class base_A {
public:
	base_A()
	{
		cout << "创建base_A" << endl;
	}
};
class base_B {
public:
	base_B()
	{
		cout << "创建base b" << endl;
	}
};
template<typename T>
class Derived :public T{
public:
	Derived(): T()
	{
		cout << "创建derived对象" << endl;
	}
};
int main()
{
	Derived<base_A>a;
	Derived<base_B>b;
	system("pause");
	return 0;
}