How to get reference to object from boost::any?

Question

I am trying to create a boost::any from a reference to an object and change it inside a given method after a boost::any_cast. But the object stays unaltered after the call. Here is a simple example of what I am trying:

class Base
{
public:
    template<typename T>
    void method(T& data)
    {
        methodImpl(boost::any(data));
    }

protected:
    virtual void methodImpl(boost::any& data) = 0;
};

class Derived : public Base
{
private:
    void methodImpl(boost::any& data)
    {
        Parameter& param = boost::any_cast<Parameter&>(data);
        // Change param attributes...
    }
};

int main()
{
    Derived derived;
    Parameter param;

    derived.method(param);
    // param hasn't changed...
}

Is there a simple way of making it work or do I have to use boost::ref and boost::reference_wrapper?

Answer 1

Based on the documentation of boost::any, it will always make a copy of the contents that you provide it:

http://www.boost.org/doc/libs/1_58_0/doc/html/boost/any.html

See item 4 and 8 in the "Description" section for documentation of the relevant constructor and assignment operator.