builder::prepareAndDeliverMsg1(msg1_arg1,msg1_arg2)
{
}

builder::prepareAndDeliverMsg2(msg2_arg1,msg2_arg2)
{
}

///----

builder::prepareMsg1(msg1_arg1,msg1_arg2)
{
}

builder::prepareMsg2(msg2_arg1,msg2_arg2)
{
}

builder::deliverMsg1(msg1_arg1)
{
    This function, inserts re-calculated msg1_arg1 into the prepared message in stage1
}

builder::deliverMsg2(msg2_arg1)
{
   This function, inserts re-calculated msg2_arg1 into the prepared message in stage1
}

// These two functions are still retained for the usage of class A
builder::prepareAndDeliverMsg1(msg1_arg1,msg1_arg2)
{
}

builder::prepareAndDeliverMsg2(msg2_arg1,msg2_arg2)
{
}

//---

class base {
    virtual bool prepareMsg1() = 0;
    virtual bool prepareMsg2() = 0;
    virtual bool deliverMsg1() = 0;
    virtual bool deliverMsg2() = 0;
    bool prepareAndDeliverMsg1(){
    	prepareMsg1();
    	deliverMsg1();
    }
    bool prepareAndDeliverMsg2(msg2_arg1,msg2_arg2){
    	prepareMsg2();
    	deliverMsg2();
    }
};

class base {
    virtual bool prepareMsg1(args) {//not pure virtual
        //do the common stuff
    }
};

class derived {
    bool prepareMsg1( args ) {
        base::prepareMsg1(args);
        //code to specailise the message
    }
};

class TBaseMsg
{
public:
   virtual void prepare() = 0;
   virtual void deliver() = 0;
}