Can I use a void* as a parameter to a function?

Question

I am porting some code over from C# into C++ and I am having trouble using the void* to take the place of a generic object. I am trying to pass the undefined pointer as a parameter for a function but have not had an success.

Here is the code to my class:

class ReceiveRequest
{
    typedef boost::function<void (std::string *message, ssError& e, void *payload) > receiveCallback;

    public:
    receiveCallback Callback;
    void* payload;

    ReceiveRequest(receiveCallback _Callback, void* _payload)
    {
        Callback = _Callback;
        payload = _payload;
    }

    void runCallback (std::string message, ssError e)
    {
        Callback(message, e, this->payload);
    }

    ~ReceiveRequest() {  }

};

And here are the errors I receive:

In file included from StringSocket.h:16,
                 from StringSocket.cpp:8:
ReceiveRequest.h: In member function ‘void ReceiveRequest::runCallback(std::string, ssError)’:
ReceiveRequest.h:30: error: no match for call to ‘(ReceiveRequest::receiveCallback) (std::string&, ssError&, void*&)’
/home/jsander/boost/include/boost/function/function_template.hpp:761: note: candidates are: R boost::function3<R, T1, T2, T3>::operator()(T0, T1, T2) const [with R = void, T0 = std::string*, T1 = ssError&, T2 = void*]

Why does my void* variable become a void*& when I pass it as a parameter? To fix this should I just change the typedef function to take a void*& to fix my problem?

Answer 1

The problem isn't the void *, it's the std::string. The callback is expecting a pointer but you're trying to pass a plain object.

...comments about why you should avoid using plain pointers in C++ aside.