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