Software Design Patterns: The Ultimate Guide

454 Pages·2023·8.366 MB·English

by  Sufyan bin Uzayr

Software Design Patterns
Software Design Patterns are reusable solutions to software development difficul-
ties. However, a Software Design Pattern is not code; rather, it is a guide or para-
digm that helps software engineers to construct products that follow best practices.
A Design Pattern is more of a template to tackle the topic at hand than a library
or framework, which can be added and utilized right away. Object-oriented pro-
gramming (OOP) is supported by Design Patterns, which are based on the ideas of
objects (instances of a class; data with unique attributes) and classes (user-defined
types of data). Design Patterns are blueprints for resolving typical software engineer-
ing issues. They provide reproducible solutions to some of the most prevalent dif-
ficulties you’ll encounter. That said, Design Patterns aren’t a complete solution, nor
are they code, classes, or libraries that you may use in your project. They are a type
of problem-solving solution. Each job will be approached in a slightly different way.
Why Should You Learn Software Design Patterns?
As a programmer, you can use Software Design Patterns to help you build more re-
liable structures. Design Patterns give you the skills to create smart and interactive
applications or software with simple and easy problem-solving methods; they also
allow you to create the greatest user-friendly apps and change them easily to meet
the latest requirements. Design Patterns are interesting to deal with since such
knowledge enables flexible coding patterns and techniques of structure, reusable
codes, loosely written codes, classes, patterns, and so on.
This book contains:
• A step-by-step approach to problem solving and skill development
• A quick run-through of the basic concepts, in the form of a “Crash Course”
• Advanced, hands-on core concepts, with a focus on real-world problems
• Industry level coding paradigm with practice-oriented explanations
• Special emphasis on writing clean and optimized code, with additional
chapters focused on coding methodology

Software Design Patterns
The Ultimate Guide
Sufyan bin Uzayr
First edition published 2023
by CRC Press
6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742
and by CRC Press
4 Park Square, Milton Park, Abingdon, Oxon, OX14 4RN
CRC Press is an imprint of Taylor & Francis Group, LLC
© 2023 Sufyan bin Uzayr
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Library of Congress Cataloging-in-Publication Data
Names: Bin Uzayr, Sufyan, author.
Title: Software Design Patterns : the ultimate guide / Sufyan bin Uzayr.
Description: First edition. | Boca Raton : CRC Press, 2023. | Includes
bibliographical references and index.
Identifiers: LCCN 2022025677 (print) | LCCN 2022025678 (ebook) | ISBN
9781032311777 (hbk) | ISBN 9781032311760 (pbk) | ISBN 9781003308461 (ebk)
Subjects: LCSH: Software patterns.
Classification: LCC QA76.76.P37 B56 2023 (print) | LCC QA76.76.P37 (ebook) |
DDC 005.13/267--dc23/eng/20220804
LC record available at https://lccn.loc.gov/2022025677
LC ebook record available at https://lccn.loc.gov/2022025678
ISBN: 9781032311777 (hbk)
ISBN: 9781032311760 (pbk)
ISBN: 9781003308461 (ebk)
DOI: 10.1201/9781003308461
Typeset in Minion
by KnowledgeWorks Global Ltd.
Contents
Acknowledgments, xv
About the Author, xvii
Chapter 1 ◾ C rash Course in Software Design Patterns 1
WHAT IS THE PURPOSE OF DESIGN PATTERNS? 2
WHY SHOULD WE STUDY DESIGN PATTERNS? 4
DESIGN PATTERN CONFIGURATION 4
Design Pattern 4
WHAT IS THE SIGNIFICANCE OF THE DESIGN PATTERN? 5
TYPES OF DESIGN PATTERNS 5
Creational 5
Use Case of Creational Design Patterns 5
Structural 6
Use Case of Structural Design Patterns 6
Behavioral 6
Use Case of Behavioral Design Patterns 7
WHAT EXACTLY IS THE GANG OF FOUR (GOF)? 7
USAGE OF DESIGN PATTERNS 7
Developers’ Common Platform 7
Guidelines for Best Practices 7
IMPORTANCE OF LEARNING DESIGN PATTERNS 8
TYPES OF DESIGN PATTERNS 8
DESIGN PATTERNS AND THEIR APPLICATIONS 9
PATTERNS OF CREATIONAL DESIGN 9
v
vi ◾ Contents
PATTERNS OF STRUCTURAL DESIGN 10
PATTERNS OF BEHAVIORAL DESIGN 11
CRITICISM 12
Focusing on the Incorrect Issue 12
No Official Foundations 12
May Result in Inefficient Solutions 13
It is Not Notably Different from Other Abstractions 13
WHAT IS THE PURPOSE OF USING DESIGN PATTERNS? 13
DESIGN PATTERNS’ ADVANTAGES IN SOFTWARE
ENGINEERING 14
SOFTWARE DESIGN PATTERN CRITIQUES 14
BEST SOFTWARE DESIGN PATTERNS 14
PATTERNS OF POPULAR SOFTWARE ARCHITECTURE 16
LIMITATIONS OF DESIGN PATTERNS 18
PROS OF DESIGN PATTERNS 18
DESIGN PATTERN CLASSIFICATION 19
Creational Design Patterns 19
Classification of Creational Design Patterns 19
Structural Design Patterns 20
Classification of Structural Design Patterns 20
Behavioral Design Patterns 20
Classification of Behavioral Design Patterns 20
Creational Design Patterns 21
Structural Design Patterns 21
Behavioral Design Patterns 21
DESIGN PATTERNS IN JAVA 21
Design Patterns in Software Development 21
Object Orientated Programming 22
Encapsulation 22
Abstraction 22
Polymorphisms 23
Inheritance 23
Contents ◾ vii
Delegation 23
Composition 23
Aggregation 23
Contract Design 24
Cohesion 24
Principle of Least Knowledge 24
The Open-Closed Principle 24
Composition vs. Inheritance in Object-Oriented Design Patterns 25
Inheritance 25
Composition 26
Favoring Composition over Inheritance in Java (with Examples) 27
Inheritance 28
Composition 29
Composition over Inheritance 30
IS INHERITANCE EXTINCT? A CLOSER LOOK AT THE
DECORATOR PATTERN 30
Exploding Class Hierarchy 31
To the Rescue Comes the Decorator Pattern 33
Decorators Queue 34
Testability 35
Other Advantages 35
Drawbacks 36
Decorator Pattern Has Native Support 37
Abstract Decorator 38
When Should We Use Inheritance? 39
KEY POINTS 40
Chapter 2 ◾ F actory Pattern 41
FACTORY METHOD 41
UML FOR FACTORY METHOD 42
PATTERNS FOR FACTORY PATTERN DESIGN 42
Problem 42
Solution 44
viii ◾ Contents
ADVANTAGES OF USING THE FACTORY PATTERN 46
DRAWBACKS OF USING THE FACTORY PATTERN METHOD 46
APPLICABILITY 46
USES OF THE FACTORY DESIGN PATTERN 46
WHEN SHOULD WE UTILIZE FACTORY PATTERN METHODS? 47
Complex Logical Code Is Being Replaced 47
Bringing Together Related Functions under a Single Interface 47
Multiple Implementations of the Same Functionality Are
Supported 47
Integrating External Series That Are Linked 47
PROBLEMS WE CONFRONT IN THE ABSENCE OF THE
FACTORY METHOD 47
DISCUSSION 48
GENERAL GUIDELINES 48
Examples of Real-World Applications of the Factory Pattern
Method Design in Java 49
Calculate An Electricity Bill: A Real-World Application of the
Factory Method in Java 49
A Real-World Example of the Factory Design Pattern in C# 51
Chapter 3 ◾ O bserver Pattern 59
PARTICIPANTS IN DESIGN 60
A PROBLEM 60
SOLUTION BASED ON THE OBSERVER PATTERN 60
CLASS DIAGRAM 63
ADVANTAGES 64
DISADVANTAGES 64
APPLICABILITY 64
USAGE 64
OBSERVER PATTERN’S PURPOSE 65
INTENT 65
PROBLEM 65
DISCUSSION 65
Contents ◾ ix
EXAMPLE 66
CHECKLIST 66
RULES OF THUMB 66
Here’s a Real-World Example of an Observer Pattern in Java 67
IMPLEMENT THE OBSERVER PATTERN 67
Another Example 69
IObservable and IObserver (C#) Observer 71
USAGE 73
Chapter 4 ◾ T emplate Method Pattern 75
THE FACTORY METHOD VS. THE TEMPLATE METHOD 76
THE ABC LIBRARY 77
WHEN SHOULD THE TEMPLATE METHOD PATTERN
BE USED? 77
USING PYTHON TO IMPLEMENT THE TEMPLATE
METHOD DESIGN PATTERN 78
ADVANTAGES 81
DISADVANTAGES 82
APPLICABILITY 82
USAGE 82
IMPORTANT POINTS 82
TEMPLATE METHOD PATTERN IMPLEMENTATION IN JAVA 83
TEMPLATE METHOD IN C# 87
Participants 87
C# Structural Code 87
Real-World C# Code 88
Chapter 5 ◾ S ingleton Pattern 93
MOTIVATION 94
REAL-WORLD EXAMPLE 94
IMPLEMENTATION 95
Method 1: Design Pattern of Monostate/Borg Singleton 95