gistfile1.cpp

template<class Retour, class T, class I>
class Function<Retour(T, I)>
{
public:
    Function() : _inner(NULL), _func(NULL) {}
    virtual ~Function() { delete _inner; }
    template<class U>
    Function(U* obj) : _inner(NULL), _func(NULL) { _inner = new InnerClass<U>(obj); }
    Function(Retour(*func)(T, I)) : _inner(NULL), _func(func) {}

    template<class U>
    void operator=(U* obj) { delete _inner; _inner = new InnerClass<U>(obj); _func = NULL; }
    void operator=(Retour(*func)(T, I)) { _func = func; if (_inner) { delete _inner; _inner = NULL; } }

    Retour operator()(T t, I i) { return _inner ? _inner->operator()(t, i) : _func(t, i); }

private:
    class IInnerClass
    {
    public:
        virtual ~IInnerClass() {}
        virtual Retour operator()(T, I) = 0;
    };
    template<class U>
    class InnerClass : public IInnerClass
    {
    public:
        InnerClass() : _obj(NULL) {}
        InnerClass(U* obj) : _obj(obj) {}
        Retour operator()(T t, I i) { return _obj->operator()(t, i); }
    private:
        U* _obj;
    };


    IInnerClass* _inner;
    Retour(*_func)(T, I);
};



int main()
{
    Function<int(char)> f = &function;
    f('c');

    callable* call = new callable;
    Function<void(std::string const&)> h = call;
    h("Coucou");

    Function<void(char, char)> g = boost::bind(&secondfunction, _1, _2);
    g('u', 'c');

    return 0;
}