Book Image

Mastering Python Design Patterns - Second Edition

By : Kamon Ayeva, Sakis Kasampalis
Book Image

Mastering Python Design Patterns - Second Edition

By: Kamon Ayeva, Sakis Kasampalis

Overview of this book

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.
Table of Contents (17 chapters)

The proxy pattern

The proxy design pattern gets its name from the proxy (also known as surrogate) object used to perform an important action before accessing the actual object. There are four different well-known proxy types (j.mp/proxypat). They are as follows:

  • 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).
  • A virtual proxy, which uses lazy initialization to defer the creation of a computationally expensive object until the moment it is actually needed.
  • A protection/protective proxy, which controls access to a sensitive object.
  • A smart (reference) proxy, which performs extra actions when an object is accessed. Examples of such actions are reference counting and thread-safety checks.

I find virtual proxies very useful so let's see an example of how we can implement them...