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

Function Summary

Use Function when

You need to store a callback function, or function object

You want to decouple function calls from the implementation, for example between the GUI and the implementation

You want to store function objects created by binder libraries to be invoked at a later time, or multiple times

Boost.Function is an important addition to the offerings from the Standard Library. The well-known technique of using function pointers as a callback mechanism is extended to include anything that behaves like a function, including function objects created by binder libraries. Through the use of Boost.Function, it is easy to add state to the callbacks, and to adapt existing classes and member functions to be used as callback functions.

There are several advantages to using Boost.Function rather than function pointers: relaxed requirements on the signature through compatible function objects rather than exact signatures; the possibility to use binders, such as Boost.Bind and Boost.Lambda; the ability to test whether functions are emptythat is, that there is no targetbefore attempting to invoke them; and the notion of stateful objects rather than just stateless functions. Each of these advantages favor using Boost.Function over the C-style callbacks that have been prevalent in solving this type of problem. Only when the small additional cost of using Boost.Function compared to function pointers is prohibitive should the function pointer technique be considered.

Boost.Function was created by Douglas Gregor. It is a library with many powerful features, and is expertly designed and implemented to provide exceptional user value.