Book Image

Learning Python Design Patterns - Second Edition - Second Edition

By : Chetan Giridhar, Gennadiy Zlobin
Book Image

Learning Python Design Patterns - Second Edition - Second Edition

By: Chetan Giridhar, Gennadiy Zlobin

Overview of this book

With the increasing focus on optimized software architecture and design it is important that software architects think about optimizations in object creation, code structure, and interaction between objects at the architecture or design level. This makes sure that the cost of software maintenance is low and code can be easily reused or is adaptable to change. The key to this is reusability and low maintenance in design patterns. Building on the success of the previous edition, Learning Python Design Patterns, Second Edition will help you implement real-world scenarios with Python’s latest release, Python v3.5. We start by introducing design patterns from the Python perspective. As you progress through the book, you will learn about Singleton patterns, Factory patterns, and Façade patterns in detail. After this, we’ll look at how to control object access with proxy patterns. It also covers observer patterns, command patterns, and compound patterns. By the end of the book, you will have enhanced your professional abilities in software architecture, design, and development.
Table of Contents (19 chapters)
Learning Python Design Patterns Second Edition
Credits
Foreword
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

The Observer pattern methods


There are two different ways of notifying the Observer of the changes that happen in the Subject. They can be classified as push or pull models.

The pull model

In the pull model, Observers play an active role as follows:

  • The Subject broadcasts to all the registered Observers when there is any change

  • The Observer is responsible for getting the changes or pulling data from the subscriber when there is an amendment

  • The pull model is ineffective as it involves two steps—the first step where the Subject notifies the Observer and the second step where the Observer pulls the required data from the Subject

The push model

In the push model, the Subject is the one that plays a dominant role as follows:

  • Unlike the pull model, the changes are pushed by the Subject to the Observer.

  • In this model, the Subject can send detailed information to the Observer (even though it may not be needed). This can result in sluggish response times when a large amount of data is sent by the Subject...