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Mastering Python Design Patterns
Mastering Python Design Patterns

Mastering Python Design Patterns: A guide to creating smart, efficient, and reusable software , Second Edition

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Profile Icon Kamon Ayeva Profile Icon Kasampalis
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Full star icon Full star icon Full star icon Half star icon Empty star icon 3.3 (9 Ratings)
Paperback Aug 2018 248 pages 2nd Edition
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Profile Icon Kamon Ayeva Profile Icon Kasampalis
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Full star icon Full star icon Full star icon Half star icon Empty star icon 3.3 (9 Ratings)
Paperback Aug 2018 248 pages 2nd Edition
eBook
$27.98 $39.99
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$48.99
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Renews at $19.99p/m
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Mastering Python Design Patterns

The Builder Pattern

In the previous chapter, we covered the first two creational patterns, the factory method and abstract factory, which both offer approaches to improve the way we create objects in nontrivial cases.

Now, imagine that we want to create an object that is composed of multiple parts and the composition needs to be done step by step. The object is not complete unless all its parts are fully created. That's where the builder design pattern can help us. The builder pattern separates the construction of a complex object from its representation. By keeping the construction separate from the representation, the same construction can be used to create several different representations (j.mp/builderpat).

A practical example can help us understand what the purpose of the builder pattern is. Suppose that we want to create an HTML page generator. The basic structure ...

Real-world examples

In our everyday life, the builder design pattern is used in fast-food restaurants. The same procedure is always used to prepare a burger and the packaging (box and paper bag), even if there are many different kinds of burgers (classic, cheeseburger, and more) and different packages (small-sized box, medium-sized box, and so forth). The difference between a classic burger and a cheeseburger is in the representation, and not in the construction procedure. In this case, the director is the cashier who gives instructions about what needs to be prepared to the crew, and the builder is the person from the crew that takes care of the specific order.

We can also find software examples:

  • The HTML example that was mentioned at the beginning of the chapter is actually used by django-widgy (https://wid.gy/), a third-party tree editor for Django that can be used as a content...

Use cases

We use the builder pattern when we know that an object must be created in multiple steps, and different representations of the same construction are required. These requirements exist in many applications such as page generators (for example, the HTML page generator mentioned in this chapter), document converters, and user interface (UI) form creators (j.mp/pipbuild).

Some online resources mention that the builder pattern can also be used as a solution to the telescopic constructor problem. The telescopic constructor problem occurs when we are forced to create a new constructor for supporting different ways of creating an object. The problem is that we end up with many constructors and long parameter lists, which are hard to manage. An example of the telescopic constructor is listed at the Stack Overflow website (j.mp/sobuilder). Fortunately, this problem does not exist...

Implementation

Let's see how we can use the builder design pattern to make a pizza-ordering application. The pizza example is particularly interesting because a pizza is prepared in steps that should follow a specific order. To add the sauce, you first need to prepare the dough. To add the topping, you first need to add the sauce. And you can't start baking the pizza unless both the sauce and the topping are placed on the dough. Moreover, each pizza usually requires a different baking time, depending on the thickness of its dough and the topping used.

We start by importing the required modules and declaring a few Enum parameters (j.mp/pytenum) plus a constant that is used many times in the application. The STEP_DELAY constant is used to add a time delay between the different steps of preparing a pizza (prepare the dough, add the sauce, and so on) as follows:

from enum...

Summary

In this chapter, we have seen how to use the builder design pattern. We use the builder pattern for creating an object in situations where using the factory pattern (either a factory method or an abstract factory) is not a good option. A builder pattern is usually a better candidate than a factory pattern when the following applies:

  • We want to create a complex object (an object composed of many parts and created in different steps that might need to follow a specific order).
  • Different representations of an object are required, and we want to keep the construction of an object decoupled from its representation.
  • We want to create an object at one point in time, but access it at a later point.

We saw how the builder pattern is used in fast-food restaurants for preparing meals, and how two third-party Django packages, django-widgy, and django-query-builder, use it for generating...

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Key benefits

  • Master the application design using the core design patterns and latest features of Python 3.7
  • Learn tricks to solve common design and architectural challenges
  • Choose the right plan to improve your programs and increase their productivity

Description

Python is an object-oriented scripting language that is used in a wide range of categories. In software engineering, a design pattern is an elected solution for solving software design problems. Although they have been around for a while, design patterns remain one of the top topics in software engineering, and are a ready source 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 fnd 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 most of 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 effciently address commonly faced problems and develop applications, and also be comfortable working on scalable and maintainable projects of any size.

Who is this book for?

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

What you will learn

  • Explore Factory Method and Abstract Factory for object creation
  • Clone objects using the Prototype pattern
  • Make incompatible interfaces compatible using the Adapter pattern
  • Secure an interface using the Proxy pattern
  • Choose an algorithm dynamically using the Strategy pattern
  • Keep the logic decoupled from the UI using the MVC pattern
  • Leverage the Observer pattern to understand reactive programming
  • Explore patterns for cloud-native, microservices, and serverless architectures

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Publication date : Aug 31, 2018
Length: 248 pages
Edition : 2nd
Language : English
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Publication date : Aug 31, 2018
Length: 248 pages
Edition : 2nd
Language : English
ISBN-13 : 9781788837484
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Table of Contents

16 Chapters
The Factory Pattern Chevron down icon Chevron up icon
The Builder Pattern Chevron down icon Chevron up icon
Other Creational Patterns Chevron down icon Chevron up icon
The Adapter Pattern Chevron down icon Chevron up icon
The Decorator Pattern Chevron down icon Chevron up icon
The Bridge Pattern Chevron down icon Chevron up icon
The Facade Pattern Chevron down icon Chevron up icon
Other Structural Patterns Chevron down icon Chevron up icon
The Chain of Responsibility Pattern Chevron down icon Chevron up icon
The Command Pattern Chevron down icon Chevron up icon
The Observer Pattern Chevron down icon Chevron up icon
The State Pattern Chevron down icon Chevron up icon
Other Behavioral Patterns Chevron down icon Chevron up icon
The Observer Pattern in Reactive Programming Chevron down icon Chevron up icon
Microservices and Patterns for the Cloud Chevron down icon Chevron up icon
Other Books You May Enjoy Chevron down icon Chevron up icon

Customer reviews

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Rating distribution
Full star icon Full star icon Full star icon Half star icon Empty star icon 3.3
(9 Ratings)
5 star 44.4%
4 star 0%
3 star 0%
2 star 55.6%
1 star 0%
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Edward Nov 27, 2019
Full star icon Full star icon Full star icon Full star icon Full star icon 5
There's a few typos scattered throughout, but the catalog is excellent overall. It's well written and worth the cost.
Amazon Verified review Amazon
Gianguglielmo Calvi Oct 10, 2018
Full star icon Full star icon Full star icon Full star icon Full star icon 5
I am part of the generation of coders and designers that developed their core knowledge around three fundamental books:"The C++ Programming Language", "Modern C++ Design: Generic Programming and Design Patterns Applied", and "Design Patterns: Elements of Reusable Object-Oriented Software".The latter is mentioned in the very first paragraph of Mastering Python Design Patters and I can't deny that this sounded already a very positive beginning to me.I would define MPDP has a "necessary" book; it organizes important architectural design principles around python philosophy and instruct on how to get the best out of this powerful language.Its reading is smooth, accompanied by clear and well chosen examples, and by references to existing services that showcase important aspects of the techniques explained.All the most important design patterns are explored and even for those with a deep understanding of the subject will be pleasurable to discover how python is able to elegantly express them.The last sections with an overview of the Microservices and Design for the Cloud approaches, are a good bonus to see how everlasting techniques applies to contemporary scenarios.Last but not least, I have appreciated the <Other Books you may enjoy> section: it is always good to have trusted pointers to resources for extending our knowledge on a topic.MPDP is a book that I would suggest to anyone willing to raise the quality, scalability and robustness of its work with python: being a coder or a designer, you will benefit either way from the understanding of how patters interact and how complex architectures should be organized to work efficiently.
Amazon Verified review Amazon
:D Aug 24, 2020
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Especially helpful are1. Real-world examples and Use cases for the pattern.2. Discussion the Pythonic way of applying design patterns.
Amazon Verified review Amazon
Aleemuddin Aug 22, 2019
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Good
Amazon Verified review Amazon
Amazon Customer Mar 13, 2020
Full star icon Full star icon Empty star icon Empty star icon Empty star icon 2
When reading chapters like the abstract factory patterns, it seems that the authors haven't unterstood it themselves. Otherwise they could have explained why it is called abstract. The explanation e.g. is, that a normal factory is just a function and an abstract factory is the same in methods of classes. This is just wrong.All in all it doesn't make any sense to force every in Java developed Design Pattern on Python without discussion the specialty why it is even needen in Python and how the shown implementation differs from the original concept.Besides that there are too many sloppy, non pythonic idioms in the code, and many examples for how not to do it, for example using string formatting for SQL-Parameter.For a second edition of a book that is not acceptable.
Amazon Verified review Amazon
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