I've defined a function object as below:

 

  struct BaseAddrLess : public std::binary_function<Base, Base, bool>  {
        result_type operator() (const first_argument_type& lhs, const second_argument_type& rhs) const  {
              return &lhs < &rhs;
        }
  };

 

and use as a compare function in ptr_set like this: 

   ptr_set<Base, BaseAddrLess> bset;

 

when the class Base is a abstract class the vc9 compiler will complain

  use of undefined type 'boost::result_of<F>'

 

What causes this problem? How to solve it?

 

Thank you for your patience to read my poor english.

S.C. Leung