std::is_bind_expression
< cpp | utility | functional
Defined in header <functional>
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template< class T > struct is_bind_expression; |
(since C++11) | |
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 > inline constexpr bool is_bind_expression_v = is_bind_expression<T>::value; |
(since C++17) | |
Inherited from std::integral_constant
Member constants
value [static] |
true if T is a function object generated by std::bind, false otherwise (public static member constant) |
Member functions
operator bool |
converts the object to bool, returns value (public member function) |
operator() (C++14) |
returns value (public member function) |
Member types
Type | Definition |
value_type
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bool
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type
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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 {}; } 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
See also
(C++11) |
binds one or more arguments to a function object (function template) |