book

Python 3 Object-Oriented Programming - Second Edition

by Dusty Phillips

August 2015

Beginner to intermediate

460 pages

11h 20m

English

Packt Publishing

Read now

Unlock full access

Support files, eBooks, discount offers, and moreWhy subscribe?Free access for Packt account holders
What this book covers

Downloading the example codeErrataPiracyQuestions
Introducing object-oriented
Data describes objectsBehaviors are actions
Inheritance provides abstractionMultiple inheritance
Creating Python classesAdding attributesMaking it do somethingTalking to yourselfMore argumentsInitializing the objectExplaining yourself
Organizing the modulesAbsolute importsRelative imports
Basic inheritanceExtending built-insOverriding and super
The diamond problemDifferent sets of arguments
Using an abstract base classCreating an abstract base classDemystifying the magic
Raising exceptionsRaising an exceptionThe effects of an exceptionHandling exceptionsThe exception hierarchyDefining our own exceptions
Treat objects as objects
Properties in detailDecorators – another way to create propertiesDeciding when to use properties
Removing duplicate codeIn practice
Empty objects
Named tuples
Dictionary use casesUsing defaultdictCounter
Sorting lists
FIFO queuesLIFO queuesPriority queues
Python built-in functionsThe len() functionReversedEnumerateFile I/OPlacing it in context
Default argumentsVariable argument listsUnpacking arguments
Using functions as attributesCallable objects
StringsString manipulationString formattingEscaping bracesKeyword argumentsContainer lookupsObject lookupsMaking it look rightStrings are UnicodeConverting bytes to textConverting text to bytesMutable byte strings
Matching patternsMatching a selection of charactersEscaping charactersMatching multiple charactersGrouping patterns togetherGetting information from regular expressionsMaking repeated regular expressions efficient
Customizing picklesSerializing web objects
Design patterns in brief
The iterator protocol
List comprehensionsSet and dictionary comprehensionsGenerator expressions
Yield items from another iterable
Back to log parsingClosing coroutines and throwing exceptionsThe relationship between coroutines, generators, and functions
The decorator patternA decorator exampleDecorators in Python
An observer example
A strategy exampleStrategy in Python
A state exampleState versus strategyState transition as coroutines
Singleton implementation
A template example
The adapter pattern
Why test?Test-driven development
Assertion methodsReducing boilerplate and cleaning upOrganizing and running testsIgnoring broken tests
One way to do setup and cleanupA completely different way to set up variablesSkipping tests with py.test
Implementing it
ThreadsThe many problems with threadsShared memoryThe global interpreter lockThread overhead
Multiprocessing poolsQueuesThe problems with multiprocessing
AsyncIO in actionReading an AsyncIO futureAsyncIO for networkingUsing executors to wrap blocking codeStreamsExecutors

Content preview from Python 3 Object-Oriented Programming - Second Edition

The singleton pattern

The singleton pattern is one of the most controversial patterns; many have accused it of being an "anti-pattern", a pattern that should be avoided, not promoted. In Python, if someone is using the singleton pattern, they're almost certainly doing something wrong, probably because they're coming from a more restrictive programming language.

So why discuss it at all? Singleton is one of the most famous of all design patterns. It is useful in overly object-oriented languages, and is a vital part of traditional object-oriented programming. More relevantly, the idea behind singleton is useful, even if we implement that idea in a totally different way in Python.

The basic idea behind the singleton pattern is to allow exactly one ...