回调函数的使用

在消息处理的时候，一般都用switch(msgid) case的方式来处理不同消息，但是随着消息的增多，就显得不方便；

解决方法：利用回调函数，来定制查找表

http://blog.csdn.net/hjsunj/article/details/2037354

//查找表
MsgFunc dataManager::LookUp(int msgID)
{
    //声明表结构
    typedef map<int, MsgFunc> Registry;

    struct RegistryInitializer
    {
        const Registry& operator()()
        {
            //定义表
            static Registry registry;
            registry[OPP_CTN_APPINSTANCES_REQUEST] = &dataManager::appInstances;//应用实例
            return registry;
        }
    };

    //find
    static const Registry& registry = RegistryInitializer()();
    Registry::const_iterator it = registry.find(msgID);
    if(it != registry.end())
    {
        return it->second;
    }
    else
    {
        //unknown msgid
        return NULL;
    }
}

//外部调用
MsgFunc msgFunc = LookUp(msgID);
    if(msgFunc != NULL)
    {
        string coremsg = (this->*msgFunc)(baseMsg, cxt);
        if(coremsg != "")
            return coremsg;
    }
    else
    {
        //unknow msgid
    }

2，用模板类来实现查找表

///h#ifndef        __I_REG_BASE_H__#define        __I_REG_BASE_H__#if defined(_MSC_VER) && 1020 <= _MSC_VER    #pragma once#endif#include <map>#include <algorithm>using namespace std;#include "IRegExcept.h"template< class Key, class Cls, class Retn = void, class Compare = less<Key> >class    IBindDispatch0{public :    typedef    Retn (Cls::*Fun)(void);    typedef CBindException<Key>    ExcepCls;    void    Bind( const Key& key, Fun bindItem );    Retn    Invok( const Key& key, Cls& clsApp );private :    std::map< Key, Fun, Compare >    m_mpBindContainer;};template< class Key, class Cls, class Param1, class Retn = void, class Compare = less<Key> >class    IBindDispatch1{public :    typedef    Retn (Cls::*Fun)(Param1);    typedef CBindException<Key>    ExcepCls;    void    Bind( const Key& key, Fun bindItem );    Retn    Invok( const Key& key, Cls& clsApp, Param1 arg1 );private :    std::map< Key, Fun, Compare >    m_mpBindContainer;};template< class Key, class Cls, class Param1, class Param2, class Retn = void, class Compare = less<Key> >class    IBindDispatch2{public :    typedef    Retn (Cls::*Fun)(Param1,Param2);    typedef CBindException<Key>    ExcepCls;    void    Bind( const Key& key, Fun bindItem );    Retn    Invok( const Key& key, Cls& clsApp, Param1 arg1, Param2 arg2 );private :    std::map< Key, Fun, Compare >    m_mpBindContainer;};template< class Key, class Cls, class Param1, class Param2, class Param3, class Retn = void, class Compare = less<Key> >class    IBindDispatch3{public :    typedef    Retn (Cls::*Fun)(Param1,Param2,Param3);    typedef CBindException<Key>    ExcepCls;    void    Bind( const Key& key, Fun bindItem );    Retn    Invok( const Key& key, Cls& clsApp, Param1 arg1, Param2 arg2, Param3 arg3);private :    std::map< Key, Fun, Compare >    m_mpBindContainer;};#include "IRegCplusplus.inl"#endif////////////cpptemplate< class Key, class Cls, class Retn, class Compare >void    IBindDispatch0< Key, Cls, Retn, Compare >::Bind( const Key& key, Fun bindItem ){    if ( NULL != bindItem ) {        m_mpBindContainer[key] = bindItem;    }}template< class Key, class Cls, class Retn, class Compare >Retn    IBindDispatch0< Key, Cls, Retn, Compare >::Invok( const Key& key, Cls& clsApp ){    std::map< Key, Fun, Compare >::iterator it = m_mpBindContainer.find(key);    if ( it == m_mpBindContainer.end() )    {        throw    ExcepCls(key, "Can't Find Key!");        return    Retn(0);    }    return (clsApp.*(it->second))();}//////////////////////////////////////////////////////////////////////////template< class Key, class Cls, class Param1, class Retn, class Compare >void    IBindDispatch1< Key, Cls, Param1, Retn, Compare >::Bind( const Key& key, Fun bindItem ){    if ( NULL != bindItem ) {        m_mpBindContainer[key] = bindItem;    }}template< class Key, class Cls, class Param1, class Retn, class Compare >Retn    IBindDispatch1< Key, Cls, Param1, Retn, Compare >::Invok( const Key& key, Cls& clsApp, Param1 arg1 ){    std::map< Key, Fun, Compare >::iterator it = m_mpBindContainer.find(key);    if ( it == m_mpBindContainer.end() )    {        throw    ExcepCls(key, "Can't Find Key!");        return    Retn(0);    }    return (clsApp.*(it->second))(arg1);}//////////////////////////////////////////////////////////////////////////template< class Key, class Cls, class Param1, class Param2, class Retn, class Compare >void    IBindDispatch2< Key, Cls, Param1, Param2, Retn, Compare >::Bind( const Key& key, Fun bindItem ){    if ( NULL != bindItem ) {        m_mpBindContainer[key] = bindItem;    }}template< class Key, class Cls, class Param1, class Param2, class Retn, class Compare >Retn    IBindDispatch2< Key, Cls, Param1, Param2, Retn, Compare >::Invok( const Key& key, Cls& clsApp, Param1 arg1, Param2 arg2 ){    std::map< Key, Fun, Compare >::iterator it = m_mpBindContainer.find(key);    if ( it == m_mpBindContainer.end() )    {        throw    ExcepCls(key, "Can't Find Key!");        return    Retn(0);    }    return (clsApp.*(it->second))(arg1,arg2);}//////////////////////////////////////////////////////////////////////////template< class Key, class Cls, class Param1, class Param2, class Param3, class Retn, class Compare >void    IBindDispatch3< Key, Cls, Param1, Param2, Param3, Retn, Compare >::Bind( const Key& key, Fun bindItem ){    if ( NULL != bindItem ) {        m_mpBindContainer[key] = bindItem;    }}template< class Key, class Cls, class Param1, class Param2, class Param3, class Retn, class Compare >Retn    IBindDispatch3< Key, Cls, Param1, Param2, Param3, Retn, Compare >::Invok( const Key& key, Cls& clsApp, Param1 arg1, Param2 arg2, Param3 arg3 ){    std::map< Key, Fun, Compare >::iterator it = m_mpBindContainer.find(key);    if ( it == m_mpBindContainer.end() )    {        throw    ExcepCls(key, "Can't Find Key!");        return    Retn(0);    }    return (clsApp.*(it->second))(arg1,arg2,arg3);}////////////////////////////////////////////////////////////////////////////////////exception.h#ifndef __I_REG_EXCEPTION_H__#define __I_REG_EXCEPTION_H__template< class Key >class CBindException{    CBindException() : m_pError(NULL) {}public :    CBindException(const Key& keyVal, const char* pErrorDescrip = NULL )        :m_stKeyVal(keyVal)        ,m_pError(pErrorDescrip)    {    }    Key            GetKeyVal( void )    {        return    m_stKeyVal;    }    const char*    GetErrorDescrip( void ) { return m_pError; }private :    Key            m_stKeyVal;    const char* m_pError;};#endif