A Primer on Design Patterns
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A Primer on Design Patterns

First Edition

About the Book

The objective of the book is to introduce its reader to the world of design patterns by working through some important ones. It is not an exaustive reference text on design patterns, rather a friendly tutorial type text. The reader is expected to be familiar with programming in an object oriented language like Java or Python. 

About the Author

Rahul Batra
Rahul Batra

Rahul Batra was first introduced to programming during 1996 in GWBASIC, but he did not seriously foray into it till 2001 when he started learning C++. Along the way, there were dabblings in many other languages like Python, Ruby, Perl and Java. He has worked in many domains like enterprise backup, ad-tech, financial softwares and analytics.

Rahul has been programming professionally since 2006 and currently lives and works in Gurgaon, India.

Table of Contents

  • Preface
  • About the author
  • Acknowledgements
  • Introducing Design Patterns
    • What are design patterns?
    • History of design patterns
    • The language choice
    • Pattern abuse
  • Strategy Pattern
    • Inheritance might not be your best friend
    • Composition as an alternative to inheritance
    • What is the volatile part of your code?
    • Implementing the strategy pattern
    • Our strategy pattern implementation migrated to Python
  • Decorator Pattern
    • Permutations and combinations
    • Decorating the same entity
    • Using our decorators
    • The decorator stripped to its core
    • Enter the Abstract Base Class of Python
  • Factory Pattern
    • The Limitations of Object Construction
    • Enter the Simple Factory
    • Factory Method
    • Implementing the simple factory in Python
  • Observer Pattern
    • Where does the Observer pattern fit?
    • Implementing the Observer pattern in Python
    • Java’s take on the Observer
    • The built-in Observer implementation in Java
  • Template Method Pattern
    • T’was a time of email clients
    • The template method in Java
    • Hooks
    • The template method in Python
  • Singleton Pattern
    • Implementing singletons in Java
    • Complications in a multi-threaded environment
    • Implementing singletons in Python
    • The problem with Singletons
  • Further Reading

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