Get memory address of member function?

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谎友^
谎友^ 2020-12-04 17:50

How do I get the absolute address of a member function in C++? (I need this for thunking.)

Member function pointers don\'t work because I can\'t convert the

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  •  清歌不尽
    2020-12-04 18:29

    There exists a syntax to get the address of the member function in MSVC (starting from MSVC 2005 IMHO). But it's pretty tricky. Moreover, the obtained pointer is impossible to cast to other pointer type by conventional means. Though there exists a way to do this nevertheless.

    Here's the example:

    // class declaration
    class MyClass
    {
    public:
        void Func();
        void Func(int a, int b);
    };
    
    // get the pointer to the member function
    void (__thiscall MyClass::* pFunc)(int, int) = &MyClass::Func;
    
    // naive pointer cast
    void* pPtr = (void*) pFunc; // oops! this doesn't compile!
    
    // another try
    void* pPtr = reinterpret_cast(pFunc); // Damn! Still doesn't compile (why?!)
    
    // tricky cast
    void* pPtr = (void*&) pFunc; // this works
    

    The fact that conventional cast doesn't work, even with reinterpret_cast probably means that MS doesn't recommend this casting very strongly.

    Nevertheless you may do this. Of course this is all implementation-dependent, you must know the appropriate calling convention to do the thunking + have appropriate assembler skills.

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