Subjects

A subject is an entity that is simultaneously an Observer and an Observable. It helps to relay notifications from one Observable to a set of Observers. We can implement sophisticated techniques such as the caching and buffering of data. We can also use a subject to convert a hot Observable into a cold Observable. There are four variants of subjects implemented in RxCpp. They are as follows:

• SimpleSubject
• BehaviorSubject
• ReplaySubject
• SynchronizeSubject

Let's write a simple program that will subscribe data as an Observer and act as an Observable for a pair of subscribers:

//------- SimpleSubject.cpp 
#include <rxcpp/rx.hpp> 
#include <memory> 
int main(int argc, char *argv[]) { 
    //----- Create an instance of Subject 
    rxcpp::subjects::subject<int> subject; 
    //----- Retreive the Observable  
    //----- attached to the Subject 
    auto observable = subject.get_observable(); 
    //------ Subscribe Twice 
    observable.subscribe( [] ( int v ) { printf("1--...