【设计模式】策略模式(经过改进的)

//【ToDo上下文】类
class CTodoContext 
{
public:
    //构造函数的参数为一个【活的名字】
    //构造函数根据这个名字去实例化不同的子类
    //将子类指针赋值给抽象基类指针
    CTodoContext(string strWorkName);
    void DoSomething();  //此函数非虚，和【干活】类及其子类没有关系

    virtual ~CTodoContext();

protected:
    CDoSomething* m_ptrDoSomething;
};

CTodoContext::CTodoContext(string strWorkName)
{
    //在构造函数中获取 【干活】类的动态类型
    if (strWorkName == string("软件开发"))
    {
        m_ptrDoSomething = new CSoftDevelop();
    }
    else if (strWorkName == string("市场拓展"))
    {
        m_ptrDoSomething = new CBusinessDevelop();
    }
    else if (strWorkName == string("数据处理"))
    {
        m_ptrDoSomething = new CDataHandle();
    }
    else
    {
        m_ptrDoSomething = NULL;
    } 
}

void CTodoContext::DoSomething()
{
    if (NULL != m_ptrDoSomething) 
        m_ptrDoSomething->DoSomething(); 
}

CTodoContext::~CTodoContext()
{
    if(NULL != m_ptrDoSomething) delete m_ptrDoSomething;
}