std::mem_fun1_t

template <class S, class T, class A>
  class mem_fun1_t : public binary_function <T*,A,S>
{
  S (T::*pmem)(A);
public:
  explicit mem_fun1_t ( S (T::*p)(A) ) : pmem (p) {}
  S operator() (T* p, A x) const
    { return (p->*pmem)(x); }
};