Book Image

Software Architecture with Python

By : Anand Balachandran Pillai
Book Image

Software Architecture with Python

By: Anand Balachandran Pillai

Overview of this book

This book starts by explaining how Python fits into an application's architecture. As you move along, you will get to grips with architecturally significant demands and how to determine them. Later, you’ll gain a complete understanding of the different architectural quality requirements for building a product that satisfies business needs, such as maintainability/reusability, testability, scalability, performance, usability, and security. You will also use various techniques such as incorporating DevOps, continuous integration, and more to make your application robust. You will discover when and when not to use object orientation in your applications, and design scalable applications. The focus is on building the business logic based on the business process documentation, and understanding which frameworks to use and when to use them. The book also covers some important patterns that should be taken into account while solving design problems, as well as those in relatively new domains such as the Cloud. By the end of this book, you will have understood the ins and outs of Python so that you can make critical design decisions that not just live up to but also surpassyour clients’ expectations.
Table of Contents (18 chapters)
Software Architecture with Python
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
Index

Patterns in Python – Creational


In this section, we will take a look at a few of the common creational patterns. We will start with Singleton, and then go on to Prototype, Builder, and Factory, in that order.

The Singleton pattern

The Singleton pattern is one of the most well-known and easily understood patterns in the entire pantheon of design patterns. It is usually defined as:

A Singleton is a class which has only one instance and a well-defined point of access to it.

The requirements of a Singleton can be summarized as follows:

  • A class must have only one instance accessible via a well-known access point

  • The class must be extensible by inheritance without breaking the pattern

  • The simplest Singleton implementation in Python is shown next. It is done by overriding the __new__ method of the base object type:

    # singleton.py
    class Singleton(object):
        """ Singleton in Python """
        
        _instance = None
        
        def __new__(cls):
            if cls._instance == None:
                cls._instance = object...