The Python Apprentice

The Python Apprentice

By : Robert Smallshire, Austin Bingham

Buy this Book

The Python Apprentice

By: Robert Smallshire, Austin Bingham

Buy this Book

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

www.PacktPub.com

Customer Feedback

Preface

Free Chapter

Getting started

Obtaining and installing Python 3

Starting Python command line REPL

Leaving the REPL

Code structure and significant indentation

Python culture

Importing standard library modules

Getting help()

Scalar data types: integers, floats, None and bool

Relational operators

Control flow: if-statements and while-loops

Summary

Strings and Collections

str – an immutable sequence of Unicode code points

Moment of zen

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

Summary

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

Moment of zen

Docstrings

Comments

Shebang

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

Moment of zen

Everything is an object

Summary

Exploring Built-in Collection types

tuple – an immutable sequence of objects

The tuple constructor

Strings in action

Moment of zen

range – a collection of evenly spaced integers

list in action

Dictionaries

set – an unordered collection of unique elements

Collection protocols

Summary

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

Guard clauses

Exceptions, APIs, and protocols

Choosing not to guard against TypeError

Pythonic style – EAFP versus LBYL

Clean-up actions

Moment of zen

Platform-specific code

Summary

Comprehensions, iterables, and generators

Generator expressions

Defining new types with classes

Defining classes

Instance methods

Instance initializers

Validation and invariants

Adding a second class

Collaborating classes

Moment of zen

Booking seats

Naming methods for implementation details

Sometimes the only object you need is a function

Polymorphism and duck-typing

Inheritance and implementation sharing

Summary

Files and Resource Management

Files

Context Managers

Moment of zen

Binary files

Unit testing with the Python standard library

Test cases

Fixtures

Assertions

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

Moment of zen

Summary

Debugging with PDB

Debugging commands

Palindrome debugging

Summary

Afterword – Just the Beginning

Virtual Environments

Creating a virtual environment

Activating a virtual environment

Deactivating a virtual environment

Other tools for working with virtual environments

Packaging and Distribution

Configuring a package with distutils

Installing with distutils

Packaging with distutils

Installing Third-Party Packages

Installing pip

The Python Package Index

Installing Local Packages with pip

Uninstalling Packages

Customer Reviews

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Empty blocks – the pass statement

With that said, we still have the problem of what to do with our empty except block. The solution arrives in the form of the pass keyword, which is a special statement that does precisely nothing! It's a no-op, and it's only purpose is to allow us to construct syntactically permissible blocks that are semantically empty:

def convert(s):
    """Convert a string to an integer."""
    x = -1
    try:
        x = int(s)
    except (ValueError, TypeError):
        pass
    return x

In this case though, it would be better to simplify further by using multiple return statements, doing away with the x variable completely:

def convert(s):
    """Convert a string to an integer."""
    try:
        return int(s)
    except (ValueError, TypeError):
        return -1

The Python Apprentice

By : Robert Smallshire, Austin Bingham

The Python Apprentice

By: Robert Smallshire, Austin Bingham

Overview of this book

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Empty blocks – the pass statement