Const correctness violation

[Douglas Gregor]

Boost.Function does not preserve const correctness for reference 
wrappers
e.g.

class function_object_type {
  public:
    void operator()() const {}
};

void f() {
    const function_object_type const_function_object;
    boost::function<void()> function(boost::ref(const_function_object));
    assert(function.target<function_object>() == 
&const_function_object);   //const lost
}

I can see two possible solutions for this:

    add a flag:
    enum cv_qualifiers { const_ = 1, volatile_ = 1 << 1};

    or don't unwrap references for target:
    function.target<boost::reference_wrapper<function_object> >()

The first method seems preferable because it doesn't
require the interface to change.

In Christ,
Steven Watanabe