Inheritance from base class with reference

This is a discussion on Inheritance from base class with reference within the C++ Programming forums, part of the General Programming Boards category; Hello, I have 3 classes : Tcp_Object Server : public Tcp_Object Server_Client : public Tcp_Object What I want is to ...

  1. #1
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    Inheritance from base class with reference

    Hello,

    I have 3 classes :
    • Tcp_Object
    • Server : public Tcp_Object
    • Server_Client : public Tcp_Object


    What I want is to be able for calling parent's methods. For ex.
    Code:
    Server_Client::get()
    {
        ((Server)this->parent)->getId();
    }
    How should I do that? I would make constructor to pass reference to object which is calling for that and save it. But what if I create Server object which have no parent?
    • Server_Client has parent of class Server
    • Server object doesn't have any parent


    Here is some of my code so far :

    Code:
    class Tcp_Object
    {
        protected:
            Tcp_Object& _parent;
        public:
            Tcp_Object();
            Tcp_Object(Tcp_Object& parent);
    };
    
    Tcp_Object::Tcp_Object(Tcp_Object& parent): _parent(parent)
    {
        //Looks ok I guess
    }
    
    Tcp_Object::Tcp_Object(): _parent( )
    {
       //But what if I dont have parent and I have to pass init this reference?
    }
    
    Server::Server(int port): Tcp_Object()
    {
       //
    }

  2. #2
    C++ Witch laserlight's Avatar
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    If it is possible that a Tcp_Object might not have a parent, then you should use a (smart) pointer, not a reference.
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  3. #3
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    So I made it as pointer and now trying like this :

    Code:
    Tcp_Object::Tcp_Object(): _parent(this)
    {
        cout << "construct" << endl;
    }
    
    Server::Server(int port): Tcp_Object()
    {
       //
    }
    It doesnt print nothing from base class constructor, why?

  4. #4
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    You are probably not invoking Server::Server(int). Without seeing complete code (class definition, definition of the constructors, and - importantly - your test code) it is difficult to be more specific.
    Right 98% of the time, and don't care about the other 3%.

    If I seem grumpy or unhelpful in reply to you, or tell you you need to demonstrate more effort before you can expect help, it is likely you deserve it. Suck it up, Sunshine, and read this, this, and this before posting again.

  5. #5
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    Code:
    class Tcp_Object
    {
        protected:
            Tcp_Object *_parent;
            bool _hasparent;
        public:
            bool hasParent();
            Tcp_Object* parent();
            Tcp_Object();
            Tcp_Object(Tcp_Object *parent);
    };
    
    class Server_Client : public Tcp_Object
    {
        private:
            SOCKET _sock;
            bool _isConnected;
            //threads
            DWORD serve();
        public:
            Server_Client(SOCKET socket, Tcp_Object *parent);
            SOCKET getSock();
    };
    
    class Server : public Tcp_Object
    {
        private:
            int _cap; //server's capacity
            int _port;
            bool _isActive;
            WSADATA _wsa;
            SOCKET _ListenSocket;
            struct addrinfo *result,
                        *ptr,
                        hints;
            boost::thread *_accepthread;
            Server_Clients *clients;
            bool _shutdown;
    
            //methods
            bool initWsa();
            bool createSock();
            bool bindSock();
            bool startListen();
    
            //Threads
            DWORD acceptThread();
        protected:
            //
        public:
            Server(int port);
            virtual ~Server();
            bool start();
            void setCapacity(int c);
            int getCapacity();
    };
    Code:
    Tcp_Object::Tcp_Object()
    {
        this->_hasparent = false;
        cout << "tcp_object w/o parent" << endl;
    }
    
    Tcp_Object::Tcp_Object(Tcp_Object *parent): _parent(parent)
    {
        this->_hasparent = true;
        cout << "tcp_object with parent" << endl;
    }
    
    Server::Server(int port): Tcp_Object()
    {
       //
    }
    Code:
    Server S(1234);
    S.start();

  6. #6
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    That code does not resemble what you previously described. Assuming this last code is accurate, it should be invoking Tcp_Object::Tcp_Object(), not Tcp_Object::Tcp_Object(Tcp_Object *). Given the way your code seems to have changed inconsistently between posts, I would not necessarily assume what you have posted is accurate.
    Right 98% of the time, and don't care about the other 3%.

    If I seem grumpy or unhelpful in reply to you, or tell you you need to demonstrate more effort before you can expect help, it is likely you deserve it. Suck it up, Sunshine, and read this, this, and this before posting again.

  7. #7
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    Yes I've changed reference to pointer. Constructor without arguments is for situation when object does not have parent.

    Let's say I want to use method Server::getCapacity() within Server_Client object which have Server object as parent.

    Edit: Looks like it works
    Last edited by kargo; 11-09-2011 at 04:56 AM.

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