Python Reference: An Alphabetical Guide

Python Reference: An Alphabetical Guide

Jo Foster

© 2024 Jo Foster. All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior permission of the publisher.

Acknowledgments

This book would not have been possible without the support of my family, friends, and colleagues who inspired and encouraged me throughout this project. A special thanks to the developers and open-source communities whose work laid the foundation for this reference.

Dedication

To my students, developers and designers everywhere.

Disclaimer

While every effort has been made to ensure the accuracy of the information in this book, the author and publisher assume no responsibility for errors or omissions. The information is provided as is and is intended for educational purposes only.

Python Keywords

Python keywords are a set of reserved words that have predefined meanings within the Python programming language. These words are an integral part of Python's syntax and cannot be used as identifiers (e.g., variable names, function names, or class names). Keywords perform specific tasks, define program structure, and control the flow of execution.

Control Flow: if, else, elif, for, while, break, and continue are used to manage how the program executes.

Functionality: def, return, yield, async, and await are used to define and manage functions and asynchronous behavior.

Exception Handling: try, except, finally, and raise help handle errors and exceptions gracefully.

Object-Oriented Programming: class, global, and nonlocal are used to define and manage object-oriented structures and variable scopes.

Logical and Comparison Operations: and, or, not, in, and is are used in logical and comparison operations.

Module and Resource Management: import, from, and with allow efficient handling of external modules and resources.

Python currently has 35 keywords (as of Python 3.10), which are case-sensitive and always written in lowercase.

and

The and keyword is a logical operator used to combine multiple conditions in Python. It evaluates to True only if both conditions are True; otherwise, it evaluates to False. It is often used in control flow statements to implement complex logical checks. Logical operators like and are evaluated lazily, meaning the second condition is only evaluated if necessary.

Syntax

condition1 and condition2

Example

x = 10

y = 20

if x > 5 and y > 15:

    print(Both conditions are satisfied.)

as

The as keyword is used to create an alias or assign a name to an item. It is commonly used with the import statement to simplify module references or with the with statement to manage resources. It helps improve readability and reduce repetitive code by providing shorter or more descriptive names.

Syntax

import module_name as alias

with open(file_path) as file_alias:

    # code

Example

import numpy as np

array = np.array([1, 2, 3])

print(array)

assert

The assert keyword is used for debugging purposes. It tests if a given condition evaluates to True. If the condition is False, an AssertionError is raised, optionally with a message. Assertions are useful during development to enforce expected behavior and catch errors early.

Syntax

assert condition, "Optional