Preface

Python is an object-oriented scripting language that is used in a wide range of categories. In software engineering, a design pattern is a solution for solving software design problems. Although they have been around for a while, design patterns remain one of the hot topics in software engineering and are a good source of information for software developers to solve the problems they face on a regular basis.

This book takes you through a variety of design patterns and explains them with real-world examples. You will get to grips with low-level details and concepts that show you how to write Python code, without focusing on common solutions as enabled in Java and C++. You'll also hunt sections on corrections, best practices, system architecture, and its designing aspects.

This book will help you learn the core concepts of design patterns and the way they can be used to resolve software design problems. You'll focus on all the Gang of Four (GoF) design patterns, which are used to solve everyday problems and take your skills to the next level with reactive and functional patterns that help you build resilient, scalable, and robust applications. By the end of the book, you'll be able to efficiently address commonly-faced problems and develop applications, and also be comfortable working on scalable and maintainable projects of any size.

Who this book is for

This book is for intermediate Python developers. Prior knowledge of design patterns is not required to enjoy this book.

What this book covers

Chapter 1,The Factory Pattern, will teach you how to use the Factory design pattern (Factory Method and Abstract Factory) to initialize objects, and also covers the benefits of using the Factory design pattern instead of direct object instantiation.

Chapter 2,The Builder Pattern, will teach you how to simplify the object creation process for cases typically composed of several related objects.

Chapter 3,Other Creational Patterns, will teach you how to handle other object creation situations with techniques such as creating a new object that is a full copy (hence, named clone) of an existing object, a technique offered by the Prototype pattern. You will also learn about the Singleton pattern.

Chapter 4,The Adapter Pattern, will teach you how to make your existing code compatible with a foreign interface (for example, an external library) with minimal changes.

Chapter 5,The Decorator Pattern, will teach you how to enhance the functionality of an object without using inheritance.

Chapter 6, The Bridge Pattern, will teach you how to externalize an object's implementation details from its class hierarchy to another object class hierarchy. This chapter encourages the idea of preferring composition over inheritance.

Chapter 7,The Facade Pattern, will teach you how to create a single entry point to hide the complexity of a system.

Chapter 8,Other Structural Patterns, will teach you the Flyweight, Model-View-Controller and Proxy patterns. With the Flyweight pattern, you will learn to reuse objects from an object pool to improve the memory usage and possibly the performance of your applications. The Model-View-Controller (MVC) pattern is used in application development (desktop, web) to improve maintainability by avoiding mixing the business logic with the user interface. And with the Proxy pattern, you provide a special object that acts as a surrogate or placeholder for another object to control access to it and reduce complexity and/or improve performance.

Chapter 9,The Chain of Responsibility Pattern, will teach another technique to improve the maintainability of your applications by avoiding mixing the business logic with the user interface.

Chapter 10,The Command Pattern, will teach you how to encapsulate operations (such as undo, copy, paste) as objects, to improve your application. Among the advantages of this technique, the object that invokes the command is decoupled from the object that performs it.

Chapter 11,The Observer Pattern, will teach you how to send a request to multiple receivers.

Chapter 12,The State Pattern, will teach you how to create a state machine to model a problem and the benefits of this technique.

Chapter 13,Other Behavioral Patterns, will teach you, among several other advanced programming techniques, how to create a simple language on top of Python, which can be used by domain experts without forcing them to learn how to program in Python.

Chapter 14,The Observer Pattern in Reactive Programming, will teach you how to send a notification to the registered stakeholders of a stream of data (and events), whenever there is a state change.

Chapter 15, Microservices and Patterns for the Cloud, will teach you several system design patterns which are important with today's increasing adoption of Cloud-Native applications and microservices architectures. You will learn that you can split your application into functional and/or technical services that can be maintained and deployed more independantly, using microservices-oriented frameworks, containers, and other techniques. Since you rely more and more on remote services as part of an application (for example, an API), retry mechanisms are used in places where a call is possible to fail but, if retried more than once, it is more probable to succeed. As an addition to doing retries for fault-tolerance, you will learn how to use Circuit breakers, a technique to allow one subsystem to fail without destroying the entire system. In applications that rely heavily on accessing data from a data store, using the Cache-Aside pattern can improve the performance while reading data from the data store via caching. This pattern can be used for read and update operations of data to and from the data store. Last but not least, the chapter introduces the Throttling pattern, the concept where, based on a rate-limiting or alternative technique, you can control how users consume your API or your service and make sure the service does not get overwhelmed by one particular tenant.

To get the most out of this book

Use a machine with a recent version of Windows, Linux or MacOS.
Install Python 3.6. Also, it is useful to know about advanced syntax and new syntax introduced in the Python 3 releases. You might also want to learn about idiomatic Python programming, by checkout out resources on Internet about the topic, if needed.
Install and use Docker on your machine, to easily install and run the RabbitMQ server needed to run the microservices examples for Chapter 15, Microservices and Patterns for the Cloud. If you choose to use the Docker installation method, which is more and more needed for many server software and services packaged as containers, you will find useful information here https://hub.docker.com/_/rabbitmq/ as well as here https://docs.nameko.io/en/stable/installation.html.

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Log in or register at www.packtpub.com.
Select the SUPPORT tab.
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Enter the name of the book in the Search box and follow the onscreen instructions.

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The code bundle for the book is also hosted on GitHub at https://github.com/PacktPublishing/Mastering-Python-Design-Patterns-Second-Edition. In case there's an update to the code, it will be updated on the existing GitHub repository.

We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/. Check them out!

Conventions used

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "In the Musician class, the main action is performed by the play() method."

A block of code is set as follows:

class Musician:
     def __init__(self, name):
         self.name = name

     def __str__(self):
 return f'the musician {self.name}'

     def play(self):
         return 'plays music'

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "A remote proxy, which acts as the local representation of an object that really exists in a different address space (for example, a network server)."

Note

Warnings or important notes appear like this.

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Mastering Python Design Patterns

By : Kamon Ayeva, Kasampalis

Mastering Python Design Patterns

By: Kamon Ayeva, Kasampalis

Overview of this book

Preface

Who this book is for

What this book covers

To get the most out of this book

Download the example code files

Conventions used

Note

Note

Get in touch

Reviews

Limited Time Offer

$10p/m for 3 months

Mastering Python Design Patterns

By : Kamon Ayeva, Kasampalis

Mastering Python Design Patterns

By: Kamon Ayeva, Kasampalis

Overview of this book

Preface

Who this book is for

What this book covers

To get the most out of this book

Download the example code files

Conventions used

Note

Note

Get in touch

Reviews

Limited Time Offer

$10p/m for 3 months

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