Metaprogramming with Python E-Book

Sulekha AloorRavi

• Herausgeber: Packt Publishing
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 327

Veröffentlichungsjahr: 2022

Beschreibung

Effective and reusable code makes your application development process seamless and easily maintainable. With Python, you will have access to advanced metaprogramming features that you can use to build high-performing applications.
The book starts by introducing you to the need and applications of metaprogramming, before navigating the fundamentals of object-oriented programming. Next, you will learn about simple decorators, work with metaclasses, and later focus on introspection and reflection. You’ll also delve into generics and typing before defining templates for algorithms. As you progress, you will understand your code using abstract syntax trees and explore method resolution order. This Python book also shows you how to create your own dynamic objects before structuring the objects through design patterns. Finally, you will learn simple code-generation techniques along with discovering best practices and eventually building your own applications.
By the end of this learning journey, you’ll have acquired the skills and confidence you need to design and build reusable high-performing applications that can solve real-world problems.

Leseprobe

Metaprogramming with Python

A programmer’s guide to writing reusable code to build smarter applications

Sulekha AloorRavi

BIRMINGHAM—MUMBAI

Metaprogramming with Python

Copyright © 2022 Packt Publishing

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First published: August 2022

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ISBN 978-1-83855-465-1

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To my husband, Dileep V, and to all my family members, for their sacrifices and for exemplifying the power of determination during one of the toughest times of our lives.

– Sulekha AloorRavi

Contributors

About the author

Sulekha AloorRavi is an engineer and data scientist with a wide technical breadth and deep understanding of many technologies and systems. Her background has led her to working on the advanced Python-based application development in the field of artificial intelligence. She enjoys solving real-world business problems with technology and working with data science and business intelligence teams to deliver real value.

She has 15+ years of experience in software engineering and has worked with major IT solution providers and international banks. She graduated with an engineering degree in information technology and later completed a postgraduate program in big data and machine learning. She also enjoys teaching artificial intelligence and machine learning.

I want to thank the people who have been close to me and supported me, especially my husband, Dileep, my nephew, Sathvik, and all my family members.

About the reviewers

Florian Dahlitz has worked in the IT industry together with companies in the insurance, banking, and public industries to realize digitalization and automation as well as AI projects. He received a BSc in applied computer science from the Baden-Württemberg Cooperative State University and will shortly receive his MSc in information systems engineering and management from the Karlsruhe Institute of Technology (KIT). Florian enjoys teaching others programming in Python and helps them raise their Python skills to the next level. He spends his free time in nature and likes to capture landscapes with his camera. 

Sri Manikanta Palakollu is a full-stack web developer with experience in Java, Python, C, C++, databases, AEM, machine learning, and data science. He is a tech reviewer for various tech book publishers. He has published many articles in various fields, such as data science, programming, and cybersecurity, in publications such as HackerNoon, freeCodeCamp, and DDI. He also wrote a book named Practical System Programming with C, Apress Publications.

Sri Manikanta has won a national-level hackathon and regularly contributes to various open source projects. He has mentored more than 5,000 students in many national- and international-level coding hackathons hosted by multiple organizations, colleges, and universities.

Dr. Madhavi Vaidya is an experienced and qualified academician and researcher with a demonstrated history of working in the education management industry, skilled in various programming languages. 

Dr. Madhavi has an understanding and knowledge of various programming and database technologies, data analytics, information retrieval, software engineering, and project management. She is a strong education professional with a Master of Computer Applications and Doctor of Philosophy in the subject of computer science and engineering. One of the key areas of her research is big data analytics using Hadoop MapReduce and various big data technologies. 

Table of Contents

Preface

Part 1: Fundamentals – Introduction to Object-Oriented Python and Metaprogramming

Chapter 1: The Need for and Applications of Metaprogramming

Technical requirements

An overview of metaprogramming

Metaprogramming – a practical introduction

Metadata of the add function

Resolving type errors using metaprogramming

Understanding why we need metaprogramming

Don’t Repeat Yourself

Exploring the applications of metaprogramming

Summary

Chapter 2: Refresher of OOP Concepts in Python

Technical requirements

Introducing our core example

Creating classes

Understanding objects

Applying methods

Implementing inheritance

Extending to multiple inheritance

Understanding polymorphism

Polymorphism within inheritance

Polymorphism in independent classes

Hiding details with abstraction

Protecting information with encapsulation

Private members

Protected members

Summary

Part 2: Deep Dive – Building Blocks of Metaprogramming I

Chapter 3: Understanding Decorators and their Applications

Technical requirements

Looking into simple function decorators

Understanding function decorators with an application

Exchanging decorators from one function to another

Applying multiple decorators to one function

Exploring class decorators

Understanding class decorators with an application

Getting to know built-in decorators

The static method

The class method

Summary

Chapter 4: Working with Metaclasses

Technical requirements

Overview of metaclasses

The structure of a metaclass

Analyzing the arguments

The application of metaclasses

Inheriting the metaclass

Inheriting as a parent and metaclass

Switching metaclasses

Inheritance in metaclasses

Manipulating class variables

Summary

Chapter 5: Understanding Introspection

Technical requirements

Introducing built-in functions

Using the built-in id function

Debugging unintentional assignments using id

Finding out whether an object is callable

Checking whether an object has an attribute

Checking whether an object is an instance

Checking whether an object is a subclass

Understanding the usage of property

Using property as a decorator

Summary

Chapter 6: Implementing Reflection on Python Objects

Technical requirements

Introducing built-in functions used in reflection

Using id to delete duplicates

Using callable to dynamically check and generate methods

Using hasattr to set values

Using isinstance to modify an object

Using issubclass to modify a class

Applying property on a class

Summary

Chapter 7: Understanding Generics and Typing

Technical requirements

What are generics?

How are generics connected to metaprogramming?

How are generics handled in Python?

What happens when data types are specified?

Type hints as annotations

Typing with explicit type checks – approach 1

Creating a class to implement type checking

Creating a class to test type checking

Typing with explicit type checks – approach 2

Creating a class to implement type checking

Creating a class to test type checking

Adding data types with constraints

Creating a simple custom data type

Creating a domain-specific data type

Summary

Chapter 8: Defining Templates for Algorithms

Technical requirements

Explaining a sequence of operations

Back to our core example

The vegetables and dairy counter

Less than 10 items counter

The greater than 10 items counter

Electronics counter

Defining the sequence of methods

The vegetable counter

Less than 10 items counter

Greater than 10 items counter

The electronics counter

Identifying the common functionalities

Designing templates

Summary

Part 3: Deep Dive – Building Blocks of Metaprogramming II

Chapter 9: Understanding Code through Abstract Syntax Tree

Technical requirements

Exploring the ast library

Inspecting Python code with abstract syntax trees

Reviewing simple code using ast

Modifying simple code using ast

Understanding abstract syntax trees with applications

Understanding the ast of a class

Modifying the ast of a code block by parsing

Modifying the ast of a code block by transforming nodes

Summary

Chapter 10: Understanding Method Resolution Order of Inheritance

Technical requirements

Understanding the MRO of a class

Understanding MRO in single inheritance

Understanding MRO in multiple inheritances

Reviewing MRO in multilevel inheritance

Understanding the importance of modifying the order of inheritance

Impact of unintended change of order in inheritance

Summary

Chapter 11: Creating Dynamic Objects

Technical requirements

Exploring type for dynamic objects

Creating multiple instances of a class dynamically

Creating dynamic classes

Creating multiple dynamic classes

Creating dynamic attributes and methods

Defining attributes dynamically

Defining methods dynamically

Summary

Chapter 12: Applying GOF Design Patterns – Part 1

Technical requirements

An overview of design patterns

Exploring behavioral design patterns

Understanding the chain of responsibility

Learning about the command design pattern

The strategy design pattern

Summary

Chapter 13: Applying GOF Design Patterns – Part 2

Technical requirements

Exploring structural design patterns

Understanding the bridge pattern

Understanding the facade pattern

Understanding the proxy pattern

Exploring creational design patterns

Understanding the factory method

Understanding the prototype method

Understanding the singleton pattern

Summary

Chapter 14: Generating Code from AST

Technical requirements

Generating a simple class with a template

Generating multiple classes from a list

Generating a class with attributes

Generating a class with methods

Generating a class with an init method

Generating a class with a user-defined method

Defining a custom class factory

Developing a code generator to generate a simple library

Summary

Chapter 15: Implementing a Case Study

Technical requirements

Explaining the case study

Defining base classes

Developing a code generator library

Generating code

Designing an execution framework

Summary

Chapter 16: Following Best Practices

Technical requirements

Following PEP 8 standards

Indentation

Neat representation

Writing clear comments for debugging and reusability

Adding documentation strings

Documentation string for metaprogramming

Naming conventions

Class names

Variables

Functions and methods

Avoiding the reuse of names

Avoiding metaprogramming where not required

Summary

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Part 1: Fundamentals – Introduction to Object-Oriented Python and Metaprogramming

The objective of this section is to give you an overview of the concept of metaprogramming, its usage, and its advantages in building Python-based applications. This section also covers the basics of object-oriented programming in Python, such as the usage of classes, functions, and objects, to help you familiarize yourself with the basic concepts, before deep diving into the complex properties of metaprogramming. 

This part contains the following chapters:

Chapter 1, The Need for and Applications of MetaprogrammingChapter 2, Refresher of OOP Concepts in Python