Learning Python Design Patterns

311 Pages·2016·2.74 MB·English

by  Chetan Giridhar

Learning Python Design Patterns Second
Edition
Table of Contents
Learning Python Design Patterns Second Edition
Credits
Foreword
About the Author
About the Reviewer
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Preface
What this book covers
What you need for this book
Who this book is for
Conventions
Reader feedback
Customer support
Downloading the example code
Errata
Piracy
Questions
1. Introduction to Design Patterns
Understanding object-oriented programming
Objects
Classes
Methods
Major aspects of object-oriented programming
Encapsulation
Polymorphism
Inheritance
Abstraction
Composition
Object-oriented design principles
The open/close principle
The inversion of control principle
The interface segregation principle
The single responsibility principle
The substitution principle
The concept of design patterns
Advantages of design patterns
Taxonomy of design patterns
Context – the applicability of design patterns
Patterns for dynamic languages
Classifying patterns
Creational patterns:
Structural patterns
Behavioral patterns
Summary
2. The Singleton Design Pattern
Understanding the Singleton design pattern
Implementing a classical Singleton in Python
Lazy instantiation in the Singleton pattern
Module-level Singletons
The Monostate Singleton pattern
Singletons and metaclasses
A real-world scenario – the Singleton pattern, part 1
A real-world scenario – the Singleton pattern, part 2
Drawbacks of the Singleton pattern
Summary
3. The Factory Pattern – Building Factories to Create Objects
Understanding the Factory pattern
The Simple Factory pattern
The Factory Method pattern
Implementing the Factory Method
Advantages of the Factory method pattern
The Abstract Factory pattern
Implementing the Abstract Factory pattern
The Factory method versus Abstract Factory method
Summary
4. The Façade Pattern – Being Adaptive with Façade
Understanding Structural design patterns
Understanding the Façade design pattern
A UML class diagram
Façade
System
Client
Implementing the Façade pattern in the real world
The principle of least knowledge
Frequently asked questions
Summary
5. The Proxy Pattern – Controlling Object Access
Understanding the Proxy design pattern
A UML class diagram for the Proxy pattern
Understanding different types of Proxies
A virtual proxy
A remote proxy
A protective proxy
A smart proxy
The Proxy pattern in the real world
Advantages of the Proxy pattern
Comparing the Façade and Proxy patterns
Frequently asked questions
Summary
6. The Observer Pattern – Keeping Objects in the Know
Introducing Behavioral patterns
Understanding the Observer design pattern
A UML class diagram for the Observer pattern
The Observer pattern in the real world
The Observer pattern methods
The pull model
The push model
Loose coupling and the Observer pattern
The Observer pattern – advantages and disadvantages
Frequently asked questions
Summary
7. The Command Pattern – Encapsulating Invocation
Introducing the Command pattern
Understanding the Command design pattern
A UML class diagram for the Command pattern
Implementing the Command pattern in the real world
Design considerations
Advantages and disadvantages of Command patterns
Frequently asked questions
Summary
8. The Template Method Pattern – Encapsulating Algorithm
Defining the Template Method pattern
Understanding the Template Method design pattern
A UML class diagram for the Template Method pattern
The Template Method pattern in the real world
The Template Method pattern – hooks
The Hollywood principle and the Template Method
The advantages and disadvantages of the Template Method pattern
Frequently asked questions
Summary
9. Model-View-Controller – Compound Patterns
An introduction to Compound patterns
The Model-View-Controller pattern
Model – knowledge of the application
View – the appearance
Controller – the glue
A UML class diagram for the MVC design pattern
The MVC pattern in the real world
Modules
Benefits of the MVC pattern
Frequently asked questions
Summary
10. The State Design Pattern
Defining the State design pattern
Understanding the State design pattern
Understanding the State design pattern with a UML diagram
A simple example of the State design pattern
The State design pattern with v3.5 implementation
Advantages/disadvantages of the State pattern
Summary
11. AntiPatterns
An introduction to AntiPatterns
Software development AntiPatterns
Spaghetti code
Golden Hammer
Lava Flow
Copy-and-paste or cut-and-paste programming
Software architecture AntiPatterns
Reinventing the wheel
Vendor lock-in
Design by committee
Summary
Index