Sams Teach Yourself C++ in One Hour a Day, Seventh Edition

Lesson 21. Understanding Function Objects

Function objects or functors might sound exotic or intimidating, but they are entities of C++ that you have probably seen, if not also used, without having realized it. In this lesson, you learn

• The concept of function objects

• The usage of function objects as predicates

• How unary and binary predicates are implemented using function objects

The Concept of Function Objects and Predicates

On a conceptual level, function objects are objects that work as functions. On an implementation level, however, function objects are objects of a class that implement operator(). Although functions and function-pointers can also be classified as function objects, it is the capability of an object of a class that ...