消息映射深度探索(3)：使用宏简化操作

2008-01-10 19:25 231人阅读 评论(0) 收藏 举报

消息映射网的建立可以用宏定义出来，以简化派生类的操作：

#include <iostream>
#include <map>
#include <cassert>

#define PRINT( msg ) { std::cout << msg << std::endl; }
#define FUNC( func ) void func() { PRINT( #func##"()" ); }
#define MFUNC( class, func ) void func() { PRINT( #class##"::"###func##"()" ); }
#define VMFUNC( class, func ) virtual MFUNC( class, func )

enum MsgID {
    MsgID_1,
    MsgID_2,
};

namespace MFCMacro {
    class Wnd;
    typedef void (Wnd::*MemberFunc)();
    typedef std::map< int, MemberFunc > MsgRegistry;   

    struct MsgMap {
        const MsgRegistry& thisMsgRegistry;
        const MsgMap* baseMsgMap;
    };

/* MACRO BEGIN *///////////////////////////////////////////////////////////
#define MSG_BEGIN( theClass, baseClass )                        /
protected:                                                      /
    virtual const MsgMap& GetMsgMap() const {                   /
        static MsgMap msgMap = {                                /
            GetInitilizedMsgRegistry##theClass(),               /
            &baseClass::GetMsgMap()                             /
        };                                                      /
        return msgMap;                                          /
    }                                                           /
private:                                                        /
    MsgRegistry& GetInitilizedMsgRegistry##theClass() const {   /
        static MsgRegistry thisMsgRegistry;                

#define MSG_ENTRY( id, func )                                   /
        thisMsgRegistry.insert( std::make_pair( id, (MemberFunc)func ) );

#define MSG_END()                                               /
        return thisMsgRegistry;                                 /
    }
/* MACRO END *////////////////////////////////////////////////////////////

    class Wnd {
        ...   
    };

    class MyWnd : public Wnd {
        MSG_BEGIN( MyWnd, Wnd )
            MSG_ENTRY( MsgID_1, &MyWnd::Handle1 )           
        MSG_END()
    private:
        MFUNC( MyWnd, Handle1 );       
    };   
}

namespace AutoTest {
    void TestMFCMacroMsgMap() {
        using namespace MFCMacro;
        Wnd* wnd = new MyWnd;
        wnd->HandleMsg( MsgID_1 );
        wnd->HandleMsg( MsgID_2 );
    }
}

void main() {
    AutoTest::TestMFCMacroMsgMap();
}

注意

为了表述方便，上面所示的宏直接将消息映射的定义部分放在类声明中。
你也可以像MFC那样将声明和实现分开：

声明
DECLARE_MESSAGE_MAP()

实现
BEGIN_MESSAGE_MAP()
 ON_WM_XXX()
 ON_COMMAND()
 ON_MESSAGE()
 ...
END_MESSAGE_MAP()