The following code example is taken from the book
The C++ Standard Library - A Tutorial and Reference
by Nicolai M. Josuttis, Addison-Wesley, 1999
© Copyright Nicolai M. Josuttis 1999
#include <functional>
/* class for the compose_f_gxy adapter
*/
template <class OP1, class OP2>
class compose_f_gxy_t
: public std::binary_function<typename OP2::first_argument_type,
typename OP2::second_argument_type,
typename OP1::result_type>
{
private:
OP1 op1; // process: op1(op2(x,y))
OP2 op2;
public:
// constructor
compose_f_gxy_t (const OP1& o1, const OP2& o2)
: op1(o1), op2(o2) {
}
// function call
typename OP1::result_type
operator()(const typename OP2::first_argument_type& x,
const typename OP2::second_argument_type& y) const {
return op1(op2(x,y));
}
};
/* convenience function for the compose_f_gxy adapter
*/
template <class OP1, class OP2>
inline compose_f_gxy_t<OP1,OP2>
compose_f_gxy (const OP1& o1, const OP2& o2) {
return compose_f_gxy_t<OP1,OP2>(o1,o2);
}