C++ std::function variable with varying arguments

Question

In my callback system I want to store std::function (or something else) with varying arguments.

Example:

1. I want to call void()

Answer 1

The following solution might work for you (I'm not sure that the code is absolutely correct here):

Create a wrapper for std::function with virtual destructor to enable using dynamic cast

class function_wrapper_base
{
    virtual ~function_wrapper_base();
}

template 
class function_wrapper
    : public function_wrapper_base
{
public:
   std::function f;
   ...
};

Then create a class variant_function_holder

class variant_function_holder
{
    std::unique_ptr f;
    ...
    template 
    void operator()(Args&&... args)
    {
        function_wrapper::type...> * g = dynamic_cast::type...>>(f.get());

        if (g == nullptr)
        {
            // ToDo
        }

        g->f(std::forward(args)...);
    }
};