C++

Reference

<functional>

class template
<functional>

std::is_bind_expression

template <class T> struct is_bind_expression;
Is bind expression
Trait class that identifies whether T is a bind expression.

It inherits from integral_constant as being either true_type or false_type, depending on whether T is a type returned from bind or not.
It is defined with the same characteristics as either true_type or false_type, depending on whether T is a type returned from bind or not.

The bind function uses this trait to determine whether the type of each of its arguments is a subexpression (i.e., whether it is itself a type returned by bind). Users can specialize this template for types that are to be treated as bind subexpressions.

Template parameters

T
A type.

Member types

Inherited from integral_constant:
member typedefinition
value_typebool
typeeither true_type or false_type
member typedefinition
value_typebool
typeeither true_type or false_type (or a type with the same characteristics)

Member constants

member constantdefinition
valueeither true or false

Member functions

member constantdefinition
operator boolReturns either true or false

Example

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// is_bind_expression example
#include <iostream>     // std::cout, std::boolalpha
#include <functional>   // std::bind, std::plus, std::placeholders, std::is_bind_expression

int main () {
  using namespace std::placeholders;  // introduces _1
  auto increase_int = std::bind (std::plus<int>(),_1,1);

  std::cout << std::boolalpha;
  std::cout << std::is_bind_expression<decltype(increase_int)>::value << '\n';

  return 0;
}

Output:
true


See also

bind
Bind function arguments (function template)
is_placeholder
Is placeholder (class template)