Unary Function


Category: functors 
Component type: concept 
Description
A Unary Function is a kind of function object: an object that is called
as if it were an ordinary C++ function. A Unary Function is called with a
single argument.
Refinement of
Assignable
Associated types
Argument type

The type of the Unary Function's argument.

Result type

The type returned when the Unary Function is called

Notation
F

A type that is a model of Unary Function

X

The argument type of F

Result

The result type of F

f

Object of type F

x

Object of type X

Definitions
The domain of a Unary Function is the set of all permissible
values for its argument.
The range of a Unary Function is the set of all possible values
that it may return.
Valid expressions
Name

Expression

Type requirements

Return type

Function call

f(x)


Result

Expression semantics
Name

Expression

Precondition

Semantics

Postcondition

Function call

f(x)

x is in f's domain

Calls f with x as an argument, and returns a value of type Result [1]

The return value is in f's range

Complexity guarantees
Invariants
Models
Notes
[1]
Two different invocations of f may return different results, even
if f is called with the same arguments both times.
A Unary Function may refer to local state, perform I/O,
and so on. The expression f(x) is permitted to change f's state.
See also
Function Object overview, Generator, Binary Function
Adaptable Unary Function