The Python Apprentice

Book Image

The Python Apprentice

By : Robert Smallshire, Austin Bingham

Book Image

The Python Apprentice

By: Robert Smallshire, Austin Bingham

Overview of this book

Experienced programmers want to know how to enhance their craft and we want to help them start as apprentices with Python. We know that before mastering Python you need to learn the culture and the tools to become a productive member of any Python project. Our goal with this book is to give you a practical and thorough introduction to Python programming, providing you with the insight and technical craftsmanship you need to be a productive member of any Python project. Python is a big language, and it’s not our intention with this book to cover everything there is to know. We just want to make sure that you, as the developer, know the tools, basic idioms and of course the ins and outs of the language, the standard library and other modules to be able to jump into most projects.

Title Page

Credits

About the Authors

About the Authors

www.PacktPub.com

www.PacktPub.com

Customer Feedback

Customer Feedback

Preface

Free Chapter

Getting started

Getting started

Obtaining and installing Python 3

Starting Python command line REPL

Leaving the REPL

Code structure and significant indentation

Importing standard library modules

Scalar data types: integers, floats, None and bool

Relational operators

Control flow: if-statements and while-loops

Strings and Collections

Strings and Collections

str – an immutable sequence of Unicode code points

Strings with Unicode

The bytes type – an immutable sequence of bytes

list – a sequence of objects

The dict type – associating keys with values

The For-loops – iterating over series of items

Putting it all together

Modularity

Organizing code in a .py file

Defining functions

Organizing our module into functions

The Python execution model

Setting up a main function with command line argument

Built-in types and the object model

Built-in types and the object model

The nature of Python object references

Argument passing semantics – pass by object-reference

Python return semantics

Function arguments in detail

The Python type system

Variable declaration and scoping

Scopes in action

Everything is an object

Exploring Built-in Collection types

Exploring Built-in Collection types

tuple – an immutable sequence of objects

The tuple constructor

Strings in action

range – a collection of evenly spaced integers

set – an unordered collection of unique elements

Collection protocols

Exceptions

Exceptions and control flow

Handling multiple exceptions

Programmer errors

Empty blocks – the pass statement

Exception objects

Imprudent return codes

Re-raising exceptions

Exceptions are part of your function's API

Exceptions, APIs, and protocols

Choosing not to guard against TypeError

Pythonic style – EAFP versus LBYL

Clean-up actions

Platform-specific code

Comprehensions, iterables, and generators

Comprehensions, iterables, and generators

Iteration protocols

Generator functions

Generator expressions

Defining new types with classes

Defining new types with classes

Defining classes

Instance methods

Instance initializers

Validation and invariants

Adding a second class

Collaborating classes

Naming methods for implementation details

Sometimes the only object you need is a function

Polymorphism and duck-typing

Inheritance and implementation sharing

Files and Resource Management

Files and Resource Management

Context Managers

Unit testing with the Python standard library

Unit testing with the Python standard library

Unit testing example: text analysis

Using fixtures to create temporary files

Using the new fixtures

Using assertions to test behavior

Testing for exceptions

Testing for file existence

Debugging with PDB

Debugging with PDB

Debugging commands

Palindrome debugging

Afterword – Just the Beginning

Afterword – Just the Beginning

Virtual Environments

Virtual Environments

Creating a virtual environment

Activating a virtual environment

Deactivating a virtual environment

Other tools for working with virtual environments

Packaging and Distribution

Packaging and Distribution

Configuring a package with distutils

Installing with distutils

Packaging with distutils

Installing Third-Party Packages

Installing Third-Party Packages

The Python Package Index

Installing Local Packages with pip

Uninstalling Packages

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Summary

Python's standard debugger is called PDB.
PDB is a standard command-line debugger.
The pdb.set_trace() method can be used to stop program execution and enter the debugger.
Your REPL's prompt will change to (Pdb) when you're in the debugger.
You can access PDB's built-in help system by typing help.
You can use python -m pdb followed by a script name to run a program under PDB from the start.
PDB's where command shows the current call stack.
PDB's next command lets execution continue to the next line of code.
PDB's continue command lets program execution continue indefinitely, or until you stop it with Ctrl+C.
PDB's list command shows you the source code at your current location.
PDB's return command resumes execution until the end of the current function.
PDB's print command lets you see the values of objects in the debugger.
Use the quit command to exit PDB.

Along the way we found that:

The divmod() function calculates the quotient and remainder for a division operation at one time.
The reversed...