if else语句的优化

if else语句的优化

flyfish

假设假设类A的成员函数Process处理的type比较多，if else语句就比较多

void A::Process(int type, std::string s)
{

    if (type == 1)
    {
        Function1(s);
    }
    else if (type == 2)
    {
        Function2(s);
    }
    else if (type == 3)
    {
        Function3(s);
    }
}

优化为类似MFC的消息映射
头文件

class A
{   
        enum Type
    {
        Type1,
        Type2,

    };
    typedef void (A::*pFun)(std::string s);
    void Function1(std::string s);
    void Function2(std::string s);
    void CustomMessageMap();
    std::map<int, pFun>   m_pMessageMap;
    void ProcessCustomMessage(int type, std::string s);

};

实现文件

void A::CustomMessageMap()
{

    m_pMessageMap.insert(std::make_pair(A::Type1, &A::Function1));
    m_pMessageMap.insert(std::make_pair(A::Type2, &A::Function2));
}
void A::Function1(std::string s)
{}
void A::Function2(std::string s)
{}

void A::ProcessCustomMessage(int type, std::string s)
{

    auto it = m_pMessageMap.find(type);
    if (it != m_pMessageMap.end())
    {
        (this->*(it->second))(s);
    }

}