Observer
The Observer pattern, quite simply, lets one component notify other components that something happened. The pattern is used all over the place: for example, when binding data to UI, we can program domain objects such that when they change, they generate notifications that the UI can subscribe to and update the visuals.
The Observer pattern is a popular and necessary pattern, so it is not surprising that the designers of C# decided to incorporate the pattern into the language wholesale with the use of the event keyword. The use of events in C# typically uses a ...
