The pattern observer defines a ratio of one to many, in which a single object, we will call the observable be notified each time you change from state to many objects, we say observers.
The operation of this design pattern can be compared with that of a subscription to a magazine, and that observers are signed and each time the magazine, (observable), is updated, it is sent to the Observers subscribers.
The definition of the observer pattern is the following: define a dependency between objects from one to many, so that when an object changes its state, all their dependents are notified and updated automatically.
To demonstrate the use of this pattern, an example where we have a main form that has 2 buttons, one to open multiple instances of observers, which in our case are forms that display a list from a data source , An XML file more specifically, and another button to open our simulator edition, which is simply a form that will allow us to edit the data source and allow us to see that every time you alter the data our observers will be notified and updated automatically .
It is important to note that for proper implementation of the standard interfaces are used to define the role of a class as Note or Observer , which we forget, for example of how each class behaves when it is notified of a change of state.
Let’s look at the diagram of classes and then the link to download our mini-application that implements the observer pattern in C #.
Sample Observer Pattern in C #
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