2011/4/9 Joel de Guzman <joel@boost-consulting.com>

Adapted classes are different beasts. Adapted classes may not
expose their attributes by reference due to abstraction and
information hiding. It's not uncommon for a class not to actually
have an actual member variable. The best we can assume is that a
class has a getter and setter member functions. When you access
its member (e.g. using at_c or dereferencing an iterator), here's
what happens:

1) If the adapted class is immutable, it returns the class' adapted
get member function for the member.

E.g. T get_mem() const;

Really? Right after seeing your words I almost came up with a workaround...
However, it turns out that it's either me misunderstanding you or it misbehaving.

For example,
const foo f("foo"); // immutable, right?
boost::fusion::front(f); // we still get a proxy, why?

2) If the adapted class is mutable (your case), then it returns a
proxy, that when assigned to, calls the class' adapted set member
function for the member.

E.g. void set_mem(T const&);

The proxy also has a conversion to T which then returns the class'
adapted get member function for the member.

That's the best we can do.

Do you have any suggestion for using adapted class with Spirit that the OP wants to do?

Thanks.