If you take a closer look, there is only a subtle difference between these two patterns. IEnumerable<T> can be considered the pull-based equivalent of the push-based IObservable<T>. In fact, they are duals. When two entities exchange information, one entity's pull corresponds to another entity pushing the information. This duality is illustrated in the following diagram:
Let's understand this duality by looking at this sample code, a number sequence generator:
We have striven to use classic C++ constructs to write programs for this particular chapter as there are chapters on Modern C++ language features, ...
