// In header: <boost/pool/pool.hpp>

struct default_user_allocator_malloc_free {
  // types
  typedef std::size_t    size_type;        // An unsigned integral type that can represent the size of the largest object to be allocated. 
  typedef std::ptrdiff_t difference_type;  // A signed integral type that can represent the difference of any two pointers. 
  // public static functions
  static char * malloc(const size_type);
  static void free(char *const);
};