Book Image

Advanced Python Programming

By : Dr. Gabriele Lanaro, Quan Nguyen, Sakis Kasampalis
Book Image

Advanced Python Programming

By: Dr. Gabriele Lanaro, Quan Nguyen, Sakis Kasampalis

Overview of this book

This Learning Path shows you how to leverage the power of both native and third-party Python libraries for building robust and responsive applications. You will learn about profilers and reactive programming, concurrency and parallelism, as well as tools for making your apps quick and efficient. You will discover how to write code for parallel architectures using TensorFlow and Theano, and use a cluster of computers for large-scale computations using technologies such as Dask and PySpark. With the knowledge of how Python design patterns work, you will be able to clone objects, secure interfaces, dynamically choose algorithms, and accomplish much more in high performance computing. By the end of this Learning Path, you will have the skills and confidence to build engaging models that quickly offer efficient solutions to your problems. This Learning Path includes content from the following Packt products: • Python High Performance - Second Edition by Gabriele Lanaro • Mastering Concurrency in Python by Quan Nguyen • Mastering Python Design Patterns by Sakis Kasampalis
Table of Contents (41 chapters)
Title Page
About Packt

Chapter 33. The Observer Pattern

When we need to update a group of objects when the state of another object changes, a popular solution is offered by the Model-View-Controller (MVC) pattern. Assume that we are using the data of the same model in two views, for instance in a pie chart and in a spreadsheet. Whenever the model is modified, both the views need to be updated. That's the role of the Observer design pattern.

The Observer pattern describes a publish-subscribe relationship between a single object, the publisher, which is also known as the subject or observable, and one or more objects, the subscribers, also known as observers.

In the case of MVC, the publisher is the model and the subscribers are the views. There are other examples and we will discuss them throughout this chapter.

The ideas behind Observer are the same as those behind the separation of concerns principle, that is, to increase decoupling between the publisher and subscribers, and to make it easy to add/remove subscribers...