reference_wrapper Class
Wraps a reference.
template<class Ty>
class reference_wrapper
: public unary_function<T1, Ret> // see below
: public binary_function<T1, T2, Ret> // see below
{
public:
typedef Ty type;
typedef T0 result_type; // see below
reference_wrapper(Ty&);
Ty& get() const;
operator Ty&() const;
template<class T1, class T2, ..., class TN>
typename result_of<T(T1, T2, ..., TN)>::type
operator()(T1&, T2&, ..., TN&);
private:
Ty *ptr; // exposition only
};
Remarks
A reference_wrapper<Ty> is copy constructible and assignable, and holds a pointer that points to an object of type Ty.
A specialization reference_wrapper<Ty> is derived from std::unary_function<T1, Ret> (hence defining the nested type result_type as a synonym for Ret and the nested type argument_type as a synonym for T1) only if the type Ty is:
a function type or pointer to function type taking one argument of type T1 and returning Ret; or
a pointer to a member function Ret T::f() cv, where cv represents the member function's cv-qualifiers; the type T1 is cv T*; or
a class type that is derived from unary_function<T1, Ret>.
A specialization reference_wrapper<Ty> is derived from std::binary_function<T1, T2, Ret> (hence defining the nested type result_type as a synonym for Ret, the nested type first_argument_type as a synonym for T1, and the nested type second_argument_type as a synonym for T2) only if the type Ty is:
a function type or pointer to function type taking two arguments of types T1 and T2 and returning Ret; or
a pointer to a member function Ret T::f(T2) cv, where cv represents the member function's cv-qualifiers; the type T1 is cv T*; or
a class type that is derived from binary_function<T1, T2, Ret>.
Requirements
Header: <functional>
Namespace: std