Daniel Arbuckle's Mastering Python

Emitting events

There are three methods which take care of emitting events. These are as follows:

• One for sending normal events
• One for sending exceptions
• One for sending a "this sequence has ended" event

These are shown in the following code example:

In each case, they do a bit of error checking, then loop through the registered observers and invoke the appropriate method. These methods have names prefixed with a single underscore (_), marking them as not part of the public interface of the Observable class. They are helpers to make subclasses easier to write.

That can't possibly be a complete reactive programming system, can it? Yes and ...