Beyond the C++ Standard Library: An Introduction to Boost [Electronic resources] نسخه متنی

How Does the Function Library Improve Your Programs?

Stores function pointers and function objects for subsequent invocation

The need to store functions and function objects is common in designs with callbacks, and where functions or classes are configured with custom functionality through either function pointers or function objects. Traditionally, function pointers have been used to accommodate the need for both callbacks and delayed functions. However, using only function pointers is too limiting, and what would be better is a generalized mechanism that defines the signature of the function to be stored, and leaves it up to the caller to decide which type of function-like entity (function pointer or function object) should be provided. It would then be possible to use anything that behaves like a functionfor example, the result of using Boost.Bind and Boost.Lambda. This, in turn, means that it is possible to add state to such stored functions (because function objects are classes). This generalization is what Boost.Function offers. The library is used to store, and subsequently invoke, functions or function objects.