Book Image

C++ Reactive Programming

By : Praseed Pai, Peter Abraham
Book Image

C++ Reactive Programming

By: Praseed Pai, Peter Abraham

Overview of this book

Reactive programming is an effective way to build highly responsive applications with an easy-to-maintain code base. This book covers the essential functional reactive concepts that will help you build highly concurrent, event-driven, and asynchronous applications in a simpler and less error-prone way. C++ Reactive Programming begins with a discussion on how event processing was undertaken by different programming systems earlier. After a brisk introduction to modern C++ (C++17), you’ll be taken through language-level concurrency and the lock-free programming model to set the stage for our foray into the Functional Programming model. Following this, you’ll be introduced to RxCpp and its programming model. You’ll be able to gain deep insights into the RxCpp library, which facilitates reactive programming. You’ll learn how to deal with reactive programming using Qt/C++ (for the desktop) and C++ microservices for the Web. By the end of the book, you will be well versed with advanced reactive programming concepts in modern C++ (C++17).
Table of Contents (20 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

The Event bus pattern


The Event bus acts as a intermediary between event sources and event sinks. An event source, or producer, emits the events to a bus, and classes that have subscribed to events (consumers) will get notified. The pattern could be an instance of the Mediator design pattern. In an Event bus implementation, we have the following archetypes

  • Producers: Classes which produce events
  • Consumers: Classes which consume events
  • Controllers: Classes which act as producers and consumers

In the implementation that follows, we have omitted the implementation of Controllers. The following code implements a toy version of an Event bus:

//----------- EventBus.cpp 
#include <rxcpp/rx.hpp> 
#include <memory> 
#include <map> 
#include <algorithm> 
using namespace std; 
//---------- Event Information 
struct EVENT_INFO{ 
   int id; 
   int err_code; 
   string description; 
   EVENT_INFO() { id = err_code = 0 ; description ="default";} 
   EVENT_INFO(int pid,int perr_code...