模板模式

定义一个操作中的算法骨架，而将一些步骤延迟到子类中

class BaseClass
{
public:
 void TemplateMethod()
 {
  Operation1();
  Operation2();
 }
protected:
 virtual void Operation1() = 0;
 virtual void Operation2() = 0;
};

class ClassA : public BaseClass
{
 virtual void Operation1()
 {
  cout << "A1" << endl;
 }
 virtual void Operation2()
 {
  cout << "A2" << endl;
 }
};

class ClassB : public BaseClass
{
 virtual void Operation1()
 {
  cout << "B1" << endl;
 }
 virtual void Operation2()
 {
  cout << "B2" << endl;
 }
};

int main()
{
    ClassA *a = new ClassA;
    a->TemplateMethod();

    ClassB *b = new ClassB;
    b->TemplateMethod();
return 0;
}