Mastering Python电子书

Mastering Python

Table of Contents

Mastering Python

Credits

About the Author

About the Reviewers

www.PacktPub.com

eBooks, discount offers, and more

Why subscribe?

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Errata

Piracy

Questions

1. Getting Started – One Environment per Project

Creating a virtual Python environment using venv

Creating your first venv

venv arguments

Differences between virtualenv and venv

Bootstrapping pip using ensurepip

ensurepip usage

Manual pip install

Installing C/C++ packages

Debian and Ubuntu

Red Hat, CentOS, and Fedora

OS X

Windows

Summary

2. Pythonic Syntax, Common Pitfalls, and Style Guide

Code style – or what is Pythonic code?

Formatting strings – printf-style or str.format?

PEP20, the Zen of Python

Beautiful is better than ugly

Explicit is better than implicit

Simple is better than complex

Flat is better than nested

Sparse is better than dense

Readability counts

Practicality beats purity

Errors should never pass silently

In the face of ambiguity, refuse the temptation to guess

One obvious way to do it

Now is better than never

Hard to explain, easy to explain

Namespaces are one honking great idea

Conclusion

Explaining PEP8

Duck typing

Differences between value and identity comparisons

Loops

Maximum line length

Verifying code quality, pep8, pyflakes, and more

flake8

Pep8

pyflakes

McCabe

flake8

Pylint

Common pitfalls

Scope matters!

Function arguments

Class properties

Modifying variables in the global scope

Overwriting and/or creating extra built-ins

Modifying while iterating

Catching exceptions – differences between Python 2 and 3

Late binding – be careful with closures

Circular imports

Import collisions

Summary

3. Containers and Collections – Storing Data the Right Way

Time complexity – the big O notation

Core collections

list – a mutable list of items

dict – unsorted but a fast map of items

set – like a dict without values

tuple – the immutable list

Advanced collections

ChainMap – the list of dictionaries

counter – keeping track of the most occurring elements

deque – the double ended queue

defaultdict – dictionary with a default value

namedtuple – tuples with field names

enum – a group of constants

OrderedDict – a dictionary where the insertion order matters

heapq – the ordered list

bisect – the sorted list

Summary

4. Functional Programming – Readability Versus Brevity

Functional programming

list comprehensions

dict comprehensions

set comprehensions

lambda functions

The Y combinator

functools

partial – no need to repeat all arguments every time

reduce – combining pairs into a single result

Implementing a factorial function

Processing trees

itertools

accumulate – reduce with intermediate results

chain – combining multiple results

combinations – combinatorics in Python

permutations – combinations where the order matters

compress – selecting items using a list of Booleans

dropwhile/takewhile – selecting items using a function

count – infinite range with decimal steps

groupby – grouping your sorted iterable

islice – slicing any iterable

Summary

5. Decorators – Enabling Code Reuse by Decorating

Decorating functions

Why functools.wraps is important

How are decorators useful?

Memoization using decorators

Decorators with (optional) arguments

Creating decorators using classes

Decorating class functions

Skipping the instance – classmethod and staticmethod

Properties – smart descriptor usage

Decorating classes

Singletons – classes with a single instance

Total ordering – sortable classes the easy way

Useful decorators

Single dispatch – polymorphism in Python

Contextmanager, with statements made easy

Validation, type checks, and conversions

Useless warnings – how to ignore them

Summary

6. Generators and Coroutines – Infinity, One Step at a Time

What are generators?

Advantages and disadvantages of generators

Pipelines – an effective use of generators

tee – using an output multiple times

Generating from generators

Context managers

Coroutines

A basic example

Priming

Closing and throwing exceptions

Bidirectional pipelines

Using the state

Summary

7. Async IO – Multithreading without Threads

Introducing the asyncio library

The async and await statements

Python 3.4

Python 3.5

Choosing between the 3.4 and 3.5 syntax

A simple example of single-threaded parallel processing

Concepts of asyncio

Futures and tasks

Event loops

Event loop implementations

Event loop policies

Event loop usage

Processes

Asynchronous servers and clients

Basic echo server

Summary

8. Metaclasses – Making Classes (Not Instances) Smarter

Dynamically creating classes

A basic metaclass

Arguments to metaclasses

Accessing metaclass attributes through classes

Abstract classes using collections.abc

Internal workings of the abstract classes

Custom type checks

Using abc.ABC before Python 3.4

Automatically registering a plugin system

Importing plugins on-demand

Importing plugins through configuration

Importing plugins through the file system

Order of operations when instantiating classes

Finding the metaclass

Preparing the namespace

Executing the class body

Creating the class object (not instance)

Executing the class decorators

Creating the class instance

Example

Storing class attributes in definition order

The classic solution without metaclasses

Using metaclasses to get a sorted namespace

Summary

9. Documentation – How to Use Sphinx and reStructuredText

The reStructuredText syntax

Getting started with reStructuredText

Inline markup

Headers

Lists

Enumerated list

Bulleted list

Option list

Definition list

Nested lists

Links, references, and labels

Images

Substitutions

Blocks, code, math, comments, and quotes

Conclusion

The Sphinx documentation generator

Getting started with Sphinx

Using sphinx-quickstart

Using sphinx-apidoc

Sphinx directives

The table of contents tree directive (toctree)

Autodoc, documenting Python modules, classes, and functions

Sphinx roles

Documenting code

Documenting a class with the Sphinx style

Documenting a class with the Google style

Documenting a class with the NumPy style

Which style to choose

Summary

10. Testing and Logging – Preparing for Bugs

Using examples as tests with doctest

A simple doctest example

Writing doctests

Testing with pure documentation

The doctest flags

True and False versus 1 and 0

Normalizing whitespace

Ellipsis

Doctest quirks

Testing dictionaries

Testing floating-point numbers

Times and durations

Testing with py.test

The difference between the unittest and py.test output

The difference between unittest and py.test tests

Simplifying assertions

Parameterizing tests

Automatic arguments using fixtures

Cache

Custom fixtures

Print statements and logging

Plugins

pytest-cov

pytest-pep8 and pytest-flakes

Configuring plugins

Mock objects

Using unittest.mock

Using py.test monkeypatch

Logging

Configuration

Basic logging configuration

Dictionary configuration

JSON configuration

Ini file configuration

The network configuration

Logger

Usage

Summary

11. Debugging – Solving the Bugs

Non-interactive debugging

Inspecting your script using trace

Debugging using logging

Showing call stack without exceptions

Debugging asyncio

Handling crashes using faulthandler

Interactive debugging

Console on demand

Debugging using pdb

Breakpoints

Catching exceptions

Commands

Debugging using ipdb

Other debuggers

Debugging services

Summary

12. Performance – Tracking and Reducing Your Memory and CPU Usage

What is performance?

Timeit – comparing code snippet performance

cProfile – finding the slowest components

First profiling run

Calibrating your profiler

Selective profiling using decorators

Using profile statistics

Line profiler

Improving performance

Using the right algorithm

Global interpreter lock

Try versus if

Lists versus generators

String concatenation

Addition versus generators

Map versus generators and list comprehensions

Caching

Lazy imports

Using optimized libraries

Just-in-time compiling

Converting parts of your code to C

Memory usage

Tracemalloc

Memory profiler

Memory leaks

Reducing memory usage

Generators versus lists

Recreating collections versus removing items

Using slots

Performance monitoring

Summary

13. Multiprocessing – When a Single CPU Core Is Not Enough

Multithreading versus multiprocessing

Hyper-threading versus physical CPU cores

Creating a pool of workers

Sharing data between processes

Remote processes

Distributed processing using multiprocessing

Distributed processing using IPyparallel

ipython_config.py

ipython_kernel_config.py

ipcontroller_config.py

ipengine_config.py

ipcluster_config.py

Summary

14. Extensions in C/C++, System Calls, and C/C++ Libraries

Introduction

Do you need C/C++ modules?

Windows

OS X

Linux/Unix

Calling C/C++ with ctypes

Platform-specific libraries

Windows

Linux/Unix

OS X

Making it easy

Calling functions and native types

Complex data structures

Arrays

Gotchas with memory management

CFFI

Complex data structures

Arrays

ABI or API?

CFFI or ctypes?

Native C/C++ extensions

A basic example

C is not Python – size matters

The example explained

static

PyObject*

Parsing arguments

C is not Python – errors are silent or lethal

Calling Python from C – handling complex types

Summary

15. Packaging – Creating Your Own Libraries or Applications

Installing packages

Setup parameters

Packages

Entry points

Creating global commands

Custom setup.py commands

Package data

Testing packages

Unittest

py.test

Nosetests

C/C++ extensions

Regular extensions

Cython extensions

Wheels – the new eggs

Distributing to the Python Package Index

Summary

Index