unary_function (3C++std) - Tru64 UNIX
Standard C++ LibraryCopyright 1996, Rogue Wave Software, Inc.
unary_function - Base class for creating unary function objects.
template <class Arg, class Result>
typedef Arg argument_type;
typedef Result result_type;
Function objects are objects with an operator() defined. They are
important for the effective use of the standard library's generic
algorithms, because the interface for each algorithmic template can accept
either an object with an operator() defined or a pointer to a function.
The standard library provides both a standard set of function objects, and
a pair of classes that you can use as the base for creating your own
Function objects that take one argument are called unary function objects.
Unary function objects are required to provide the typedefs argument_type
and result_type. The unary_function class makes the task of creating
templated unary function objects easier by providing the necessary typedefs
for a unary function object. You can create your own unary function
objects by inheriting from unary_function.
function objects, and Function Objects Section in User's Guide.
ANSI X3J16/ISO WG21 Joint C++ Committee