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.youkuaiyun.com/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


cpp

template< 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