book

Go Design Patterns

Name: Go Design Patterns
Author: Mario Castro Contreras
ISBN: 9781786466204

by Mario Castro Contreras

February 2017

Intermediate to advanced

402 pages

8h 7m

English

Packt Publishing

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Go Design Patterns
Go Design Patterns
Credits
About the Author
About the Reviewer
www.PacktPub.com
Why subscribe?
Customer Feedback
Preface
What this book covers
What you need for this book
Who this book is for

Conventions
Reader feedback
Customer support
Downloading the example codeErrataPiracyQuestions
1. Ready... Steady... Go!
A little bit of history
Installing Go
LinuxGo Linux advanced installationWindowsMac OS XSetting the workspace - Linux and Apple OS X
Starting with Hello World
Integrated Development Environment - IDE
Types
Variables and constants
Operators
Flow control
The if... else statementThe switch statementThe for…range statement
Functions
What does a function look like?What is an anonymous function?ClosuresCreating errors, handling errors and returning errors.Function with undetermined number of parametersNaming returned types
Arrays, slices, and maps
ArraysZero-initializationSlicesMaps
Visibility
Zero-initialization
Pointers and structures
What is a pointer? Why are they good?Structs
Interfaces
Interfaces - signing a contract
Testing and TDD
The testing packageWhat is TDD?
Libraries
The Go get tool
Managing JSON data
The encoding package
Go tools
The golint toolThe gofmt toolThe godoc toolThe goimport tool
Contributing to Go open source projects in GitHub
Summary
2. Creational Patterns - Singleton, Builder, Factory, Prototype, and Abstract Factory Design Patterns
Singleton design pattern - having a unique instance of a type in the entire programDescriptionObjectivesExample - a unique counterRequirements and acceptance criteriaWriting unit tests firstImplementationA few words about the Singleton design pattern
Builder design pattern - reusing an algorithm to create many implementations of an interface
DescriptionObjectivesExample - vehicle manufacturingRequirements and acceptance criteriaUnit test for the vehicle builderImplementationWrapping up the Builder design pattern
Factory method - delegating the creation of different types of payments
DescriptionObjectivesThe example - a factory of payment methods for a shopAcceptance criteriaFirst unit testImplementationUpgrading the Debitcard method to a new platformWhat we learned about the Factory method
Abstract Factory - a factory of factories
DescriptionThe objectivesThe vehicle factory example, again?Acceptance criteriaUnit testImplementationA few lines about the Abstract Factory method
Prototype design pattern
DescriptionObjectiveExampleAcceptance criteriaUnit testImplementationWhat we learned about the Prototype design pattern
Summary
3. Structural Patterns - Composite, Adapter, and Bridge Design Patterns
Composite design patternDescriptionObjectivesThe swimmer and the fishRequirements and acceptance criteriaCreating compositionsBinary Tree compositionsComposite pattern versus inheritanceFinal words on the Composite pattern
Adapter design pattern
DescriptionObjectivesUsing an incompatible interface with an Adapter objectRequirements and acceptance criteriaUnit testing our Printer adapterImplementationExamples of the Adapter pattern in Go's source codeWhat the Go source code tells us about the Adapter pattern
Bridge design pattern
DescriptionObjectivesTwo printers and two ways of printing for eachRequirements and acceptance criteriaUnit testing the Bridge patternImplementationReuse everything with the Bridge pattern
Summary
4. Structural Patterns - Proxy, Facade, Decorator, and Flyweight Design Patterns
Proxy design patternDescriptionObjectivesExampleAcceptance criteriaUnit testImplementationProxying around actions
Decorator design pattern
DescriptionObjectivesExampleAcceptance criteriaUnit testImplementationA real-life example - server middlewareStarting with the common interface, http.HandlerA few words about Go's structural typingSummarizing the Decorator design pattern - Proxy versus Decorator
Facade design pattern
DescriptionObjectivesExampleAcceptance criteriaUnit testImplementationLibrary created with the Facade pattern
Flyweight design pattern
DescriptionObjectivesExampleAcceptance criteriaBasic structs and testsImplementationWhat's the difference between Singleton and Flyweight then?
Summary
5. Behavioral Patterns - Strategy, Chain of Responsibility, and Command Design Patterns
Strategy design patternDescriptionObjectivesRendering images or textAcceptance criteriaImplementationSolving small issues in our libraryFinal words on the Strategy pattern
Chain of responsibility design pattern
DescriptionObjectivesA multi-logger chainUnit testImplementationWhat about a closure?Putting it together
Command design pattern
DescriptionObjectivesA simple queueAcceptance criteriaImplementationMore examplesChain of responsibility of commandsRounding-up the Command pattern up
Summary
6. Behavioral Patterns - Template, Memento, and Interpreter Design Patterns
Template design patternDescriptionObjectivesExample - a simple algorithm with a deferred stepRequirements and acceptance criteriaUnit tests for the simple algorithmImplementing the Template patternAnonymous functionsHow to avoid modifications on the interfaceLooking for the Template pattern in Go's source codeSummarizing the Template design pattern
Memento design pattern
DescriptionObjectivesA simple example with stringsRequirements and acceptance criteriaUnit testImplementing the Memento patternAnother example using the Command and Facade patternsLast words on the Memento pattern
Interpreter design pattern
DescriptionObjectivesExample - a polish notation calculatorAcceptance criteria for the calculatorUnit test of some operationsImplementationComplexity with the Interpreter design patternInterpreter pattern again - now using interfacesThe power of the Interpreter pattern
Summary
7. Behavioral Patterns - Visitor, State, Mediator, and Observer Design Patterns
Visitor design patternDescriptionObjectivesA log appenderAcceptance criteriaUnit testsImplementation of Visitor patternAnother exampleVisitors to the rescue!
State design pattern
DescriptionObjectivesA small guess the number gameAcceptance criteriaImplementation of State patternA state to win and a state to loseThe game built using the State pattern
Mediator design pattern
DescriptionObjectivesA calculatorAcceptance criteriaImplementationUncoupling two types with the Mediator
Observer design pattern
DescriptionObjectivesThe notifierAcceptance criteriaUnit testsImplementationSummary
8. Introduction to Gos Concurrency
A little bit of history and theoryConcurrency versus parallelismCSP versus actor-based concurrency
Goroutines
Our first GoroutineAnonymous functions launched as new GoroutinesWaitGroups
Callbacks
Callback hell
Mutexes
An example with mutexes - concurrent counterPresenting the race detector
Channels
Our first channelBuffered channelsDirectional channelsThe select statementRanging over channels too!
Using it all - concurrent singleton
Unit testImplementation
Summary
9. Concurrency Patterns - Barrier, Future, and Pipeline Design Patterns
Barrier concurrency patternDescriptionObjectivesAn HTTP GET aggregatorAcceptance criteriaUnit test - integrationImplementationWaiting for responses with the Barrier design pattern
Future design pattern
DescriptionObjectivesA simple asynchronous requesterAcceptance criteriaUnit testsImplementationPutting the Future together
Pipeline design pattern
DescriptionObjectivesA concurrent multi-operationAcceptance criteriaBeginning with testsImplementationThe list generatorRaising numbers to the power of 2Final reduce operationLaunching the Pipeline patternFinal words on the Pipeline pattern
Summary
10. Concurrency Patterns - Workers Pool and Publish/Subscriber Design Patterns
Workers poolDescriptionObjectivesA pool of pipelinesAcceptance criteriaImplementationThe dispatcherThe pipelineAn app using the workers poolNo tests?Wrapping up the Worker pool
Concurrent Publish/Subscriber design pattern
DescriptionObjectivesExample - a concurrent notifierAcceptance criteriaUnit testTesting subscriberTesting publisherImplementationImplementing the publisherHandling channels without race conditionsA few words on the concurrent Observer pattern
Summary

Content preview from Go Design Patterns

Flyweight design pattern

Our next pattern is the Flyweight design pattern. It's very commonly used in computer graphics and the video game industry, but not so much in enterprise applications.

Description

Flyweight is a pattern which allows sharing the state of a heavy object between many instances of some type. Imagine that you have to create and store too many objects of some heavy type that are fundamentally equal. You'll run out of memory pretty quickly. This problem can be easily solved with the Flyweight pattern, with additional help of the Factory pattern. The factory is usually in charge of encapsulating object creation, as we saw previously.

Objectives

Thanks to the Flyweight pattern, we can share all possible states of objects in a single ...

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