Dynamic binding in C++

Question

I'm implementing a CORBA like server. Each class has remotely callable methods and a dispatch method with two possible input, a string identifying the method or an integer which would be the index of the method in a table. A mapping of the string to the corresponding integer would be implemented by a map.

The caller would send the string on the first call and get back the integer with the response so that it simply has to send the integer on subsequent calls. It is just a small optimization. The integer may be assigned dynamically on demand by the server object. The server class may be derived from another class with overridden virtual methods.

What could be a simple and general way to define the method binding and the dispatch method ?

Edit: The methods have all the same signature (no overloading). The methods have no parameters and return a boolean. They may be static, virtual or not, overriding a base class method or not. The binding must correctly handle method overriding.

The string is class hierarchy bound. If we have A::foo() identified by the string "A.foo", and a class B inherits A and override the method A::foo(), it will still be identified as "A.foo", but the dispatcher will call A::foo if the server is an A object and B::foo if it is a B object.

Edit (6 apr): In other words, I need to implement my own virtual method table (vftable) with a dynamic dispatch method using a string key to identify the method to call. The vftable should be shared among objects of the same class and behave as expected for polymorphism (inherited method override).

Edit (28 apr): See my own answer below and the edit at the end.

Answer 1

Have you considered using a combination of boost::bind and boost::function? Between these two utilities you can easily wrap any C++ callable in a function object, easily store them in containers, and generally expect it all to "just work". As an example, the following code sample works exactly the way you would expect.

#include <boost/bind.hpp>
#include <boost/function.hpp>
#include <iostream>
using namespace std;

struct A            { virtual void hello() { cout << "Hello from A!" << endl; } };
struct B : public A { virtual void hello() { cout << "Hello from B!" << endl; } };

int main( int argc, char * argv[] )
{
    A a;
    B b;
    boost::function< void () > f1 = boost::bind( &A::hello, a );
    boost::function< void () > f2 = boost::bind( &A::hello, b );
    f1();  // prints: "Hello from A!"
    f2();  // prints: "Hello from B!"
    return 0;
}