Std::is_bind_expression (3) Linux Manual Page

std::is_bind_expression – std::is_bind_expression

Synopsis

Defined in header<functional>

    template <class T>
    (since C++ 11)

        struct is_bind_expression;

If T is the type produced by a call to std::bind, this template is derived from std::true_type. For any other type, this template is derived from std::false_type.
This template may be specialized for a user-defined type T to implement UnaryTypeTrait with BaseCharacteristic of std::true_type to indicate that T should be treated by std::bind as if it were the type of a bind subexpression: when a bind-generated function object is invoked, a bound argument of this type will be invoked as a function object and will be given all the unbound arguments passed to the bind-generated object.
Helper variable template

template< class T >                                                         (since C++17)

inline constexpr bool is_bind_expression_v = is_bind_expression<T>::value;

Inherited from std::integral_constant

Member constants

value true if T is a function object generated by std::bind, false otherwise
(public static member constant)
[static]

Member functions

converts the object to bool, returns value
operator bool (public member function)

operator() returns value
(public member function)
(C++14)

Member types

Type Definition
value_type bool
type std::integral_constant<bool, value>

Example

// Run this code

#include <iostream>

#include <type_traits>

#include <functional>
struct MyBind {
    typedef int result_type;
    int operator()(int a, int b) const
    {
        return a + b;
    }
};
namespace std
{
template <>
struct is_bind_expression<MyBind> : public true_type {
};

} // namespace std
int f(int n1, int n2)

{
    return n1 + n2;
}
int main()

{
    // as if bind(f, bind(MyBind(), _1, _2), 2)
    auto b = std::bind(f, MyBind(), 2);
    std::cout << "Adding 2 to the sum of 10 and 11 gives " << b(10, 11) << '\n';
}

Output:

Adding 2 to the sum of 10 and 11 gives 23

std::is_bind_expression (3) Linux Manual Page