Standard Template Library Programmer's Guide

Name	Expression	Return type
Function call	f(x,y)	Result

Expression semantics

Name	Expression	Precondition	Semantics	Postcondition
Function call	f(x,y)	The ordered pair (x,y) is in f's domain	Calls f with x and y as arguments, and returns a value of type Result [1]	The return value is in f's range

Models

• Result (*)(X,Y)

Notes

[1] Two different invocations of f may return different results, even if f is called with the same arguments both times. A Binary Function may refer to local state, perform I/O, and so on. The expression f(x,y) is permitted to change f's state.

See also

Function Object overview, Generator, Unary Function, Adaptable Binary Function

Adaptable Generator

Category: functors

Component type: concept

Description

An Adaptable Generator is a Generator with a nested typedef that defines its result type. [1] This nested typedef makes it possible to use function object adaptors.

Refinement of

Generator

Associated types

Result type

F::result_type

The type returned when the Generator is called

Notation

F A type that is a model of Adaptable Generator

Valid expressions

None, except for those defined by Generator

Models

The STL does not include any types that are models of Adaptable Generator. An example of a user-defined Adaptable Generator is as follows.

struct counter {
 typedef int result_type;
 counter() : n(0) {}
 result_type operator()() { return n++; }
 result_type n;
};

Notes

[1] Note the implication of this: a function pointer T (*f)() is a Generator, but not an Adaptable Generator: the expression f::result_type is nonsensical.

See also

Generator, Adaptable Unary Function, Adaptable Binary Function

Adaptable Unary Function

Category: functors

Component type: concept

Description

An Adaptable Unary Function is a Unary Function with nested typedefs that define its argument type and result type. [1] [2] These nested typedef make it possible to use function object adaptors.

Refinement of

Unary Function

Associated types

Argument type	F::argument_type	The type of F's argument
Result type	F::result_type