Category: functors | Component type: concept |
First argument type | F::first_argument_type | The type of F's first argument |
Second argument type | F::second_argument_type | The type of F's second argument |
Result type | F::result_type | The type returned when the Binary Function is called |
F | A type that is a model of Binary Function |
[1] Note the implication of this: a function pointer T (*f)(X,Y) is a Binary Function, but not an Adaptable Binary Function: the expressions f::first_argument_type, f::second_argument_type, and f::result_type are nonsensical.
[2] When you define a class that is a model of Adaptable Binary Function, you must provide these typedefs. The easiest way to do this is to derive the class from the base class binary_function. This is an empty class, with no member functions or member variables; the only reason it exists is to make defining Adaptable Binary Functions more convenient. Binary_function is very similar to the base classes used by the iterator tag functions.