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- Herausgeber: Packt Publishing
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
An insightful guide to learning the Go programming language
About This Book
- Insightful coverage of Go programming syntax, constructs, and idioms to help you understand Go code effectively
- Push your Go skills, with topics such as, data types, channels, concurrency, object-oriented Go, testing, and network programming
- Each chapter provides working code samples that are designed to help reader quickly understand respective topic
Who This Book Is For
If you have prior exposure to programming and are interested in learning the Go programming language, this book is designed for you. It will quickly run you through the basics of programming to let you exploit a number of features offered by Go programming language.
What You Will Learn
- Install and configure the Go development environment to quickly get started with your first program.
- Use the basic elements of the language including source code structure, variables, constants, and control flow primitives to quickly get started with Go
- Gain practical insight into the use of Go's type system including basic and composite types such as maps, slices, and structs.
- Use interface types and techniques such as embedding to create idiomatic object-oriented programs in Go.
- Develop effective functions that are encapsulated in well-organized package structures with support for error handling and panic recovery.
- Implement goroutine, channels, and other concurrency primitives to write highly-concurrent and safe Go code
- Write tested and benchmarked code using Go's built test tools
- Access OS resources by calling C libraries and interact with program environment at runtime
In Detail
The Go programming language has firmly established itself as a favorite for building complex and scalable system applications. Go offers a direct and practical approach to programming that let programmers write correct and predictable code using concurrency idioms and a full-featured standard library.
This is a step-by-step, practical guide full of real world examples to help you get started with Go in no time at all. We start off by understanding the fundamentals of Go, followed by a detailed description of the Go data types, program structures and Maps. After this, you learn how to use Go concurrency idioms to avoid pitfalls and create programs that are exact in expected behavior. Next, you will be familiarized with the tools and libraries that are available in Go for writing and exercising tests, benchmarking, and code coverage.
Finally, you will be able to utilize some of the most important features of GO such as, Network Programming and OS integration to build efficient applications. All the concepts are explained in a crisp and concise manner and by the end of this book; you would be able to create highly efficient programs that you can deploy over cloud.
Style and approach
The book is written to serve as a reader-friendly step-by-step guide to learning the Go programming language. Each topic is sequentially introduced to build on previous materials covered. Every concept is introduced with easy-to-follow code examples that focus on maximizing the understanding of the topic at hand.
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Seitenzahl: 368
Veröffentlichungsjahr: 2016
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Table of Contents
Learning Go Programming
Learning Go Programming
Copyright © 2016 Packt Publishing
All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.
Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.
Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.
First published: October 2016
Production reference: 1201016
Published by Packt Publishing Ltd.
Livery Place
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Birmingham
B3 2PB, UK.
ISBN 978-1-78439-543-8
www.packtpub.com
Credits
Authors
Vladimir Vivien
Copy Editor
Safis Editing
Reviewers
Quintessence Anx
Parth Desai
Abhishek Kumar
Chris Schaefer
Project Coordinator
Nidhi Joshi
Commissioning Editor
Akram Hussain
Proofreader
Safis Editing
Acquisition Editor
Manish Nainnani
Indexer
Aishwarya Gangawane
Content Development Editor
Aishwarya Pandere
Graphics
Disha Haria
Technical Editor
Mohita Vyas
Production Coordinator
Nilesh Mohite
About the Author
Vladimir Vivien (@vladimirvivien) is a software engineer living in the United States. He is a previously published author and has written code in languages such as Java, JavaScript, Python, C to name a few. Vladimir has work in diverse industries including technology, publishing, financial, and healthcare. After years of building enterprise systems using Java, Vladimir came to Go for its simplicity and stayed for its concurrency and fast build time. Vladimir continues to use Go as his primary language to build and create open source software (https://github.com/vladimirivivien).
About the Reviewers
Quintessence Anx. is a superhero (also called as Cloud Engineer) at Stark & Wayne LLC by day and an astronomer with a passion for the Internet of Things by night. She is a chapter leader for her local Girl Develop It, where she empowers women programmers of all levels and abilities through classes and hands-on project experiences, as well as co-founder of City of Light 2.0, an organization working to bring more affordable, reliable, and faster internet to Western New York
Parth Desai is a polygot programmer and architect, and has worked on almost all popular languages like Golang, python, C#. He regularly contributes to various open-source golang projects, like a notification engine called “Khabar”, a http framework written in golang called “Gottp”, and media server called “moire”. He implemented url signing protocol using cryptography in python, from scratch.
He has also written custom single sign on solution (SSO) in c#, with proper implementation of oauth and saml protocols. He also developed pluggable architecture to facilitate easier adding and removing of authentication providers for the SSO. Currently, He is working as a lead backend engineer, and designing and implementing scalable systems in golang and python. You can reach out to him on linkedin at https://in.linkedin.com/in/parthdesai08. Or on his email-id [email protected].
Abhishek Kumar is a technologist in IT Industry since 2010 mainly working in Systems Programming, DevOps Practices and Security. He likes to keep in sync with all domains, paradigms and up-coming technologies to get a wholistic approach for problem solving and planning ahead. He loves to learn new programming languages. Abhishek has been using Golang since 2012. He started a timeseries datastore project in Golang by Sep'2013 and is currently pivoting it. [ @abionic | https://abhishekkr.github.io ]
Want to thank my mother ShivPyari to enable me choose my own path
Chris Schaefer software developer with a passion for learning new things. He enjoys writing code and participating in local community software events.
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Preface
Go is an open source programming language that lets programmers easily build reliable and scalable programs. It does this by offering a simple syntax which makes it fun to write correct and predictable code using concurrency idioms and a robust standard library.
Go has a large and active online community and there are several Go conferences that take place around the world yearly. Starting with https://golang.org/, you will find numerous places on the web that provide documentations, blogs, videos, and slides that cover a wide range of Go-related topics. On GitHub, the story is no different; some of the best known projects that are driving the future of cloud computing, for instance, are written in Go with an ever growing list.
As you would expect, getting started with Go is simple, fast, and well documented. However, “getting into” Go can be more challenging, especially for newcomers from other languages. My first attempt at Go failed. Even after reading the prescribed documentations and going through the tutorials, there was a gap in understanding driven by my own biases from previous programming experiences. Months later I returned to Go and got into it. This time I read the language specs, I read blogs, watch videos, and searched the web for any discussion that provided design motivations and in-depth explanations of the language.
Learning Go is a book intended to help new, and seasoned programmers alike, to get into the Go programming language. With this book, I have attempted to write the book I would have like to have read when I was starting out with Go. It distills the language specs, the documentations, the blogs, the videos, slides, and my own experiences of writing Go into content that carefully provides the right amount of depth and insights to help you understand the language and its design.
I hope that you enjoy it.
What this book covers
Chapter 1, A First Step in Go, the reader is introduced to Go at a high-level and take a tour of the features that have made the language a favorite among its adopters.
Chapter 2, Go Language Essentials, this chapter starts with a deeper exploration Go’s syntax and other language elements such as source files, variables, and operators.
Chapter 3, Go Control Flow, examines Go program control flow elements including if, loop, and switch statements.
Chapter 4, Data Types, introduces its readers to Go’s type system including detail about built-in types, type declaration, and conversion.
Chapter 5, Functions in Go, discusses the characteristics of the Go function type including definition, assignment, variadic parameters, and closures.
Chapter 6, Go Packages and Program Structures, introduces readers to the organization of functions as a logical grouping known as packages and programs.
Chapter 7, Composite Types, this chapter continues the discussion Go types by introducing the reader to Go’s composite types such as arrays, slices, maps, and structs.
Chapter 8, Methods, Interfaces, and Objects, introduces the reader to Go idioms and features that can be used to create and compose object structures.
Chapter 9, Concurrency, introduces the reader to the topics of writing concurrent programs in Go using language constructs such as goroutines and channels.
Chapter 10, Data IO in Go, covers the built-in interfaces and APIs to achieve streaming input, output, and encoding of data.
Chapter 11, Writing Networked Services, explores the Go’s standard library for creating connected applications using covering topics from low-level TCP protocols to HTTP an RPC.
Chapter 12, Code Testing, here readers are introduced to Go’s inherent support and tools for code testing and benchmarking.
What you need for this book
To follow the examples in this book, you will need Go version 1.6 or later. Go supports architectures including AMD64, x386, and ARM running the following operating systems:
Who this book is for
If you have prior exposure to programming and are interested learning the Go, this book is designed for you. While it assumes that you are familiar with concepts such as variables, data types, arrays, methods, and functions, the book is designed to allow you to follow chapter by chapter or skip around to the topics you want to learn about.
Conventions
In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.
Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "Save the source code in a file called helloworld.go anywhere inside your GOPATH."
A block of code is set as follows:
package main import "fmt" func main() { fmt.Println("Hello, World!") }Any command-line input or output is written as follows:
$> go versiongo version go1.6.1 linux/amd64New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "If all goes well, you should see the message Hello, World! output on your screen.."
Note
Warnings or important notes appear in a box like this.
Tip
Tips and tricks appear like this.
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Questions
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Chapter 1. A First Step in Go
In the first chapter of the book, you will be introduced to Go and take a tour of the features that have made the language a favorite among its adopters. The start of the chapter provides the motivation behind the Go programming language. If you are impatient, however, you are welcome to skip to any of the other topics and learn how to write your first Go program. Finally, the Go in a nutshell section provides a high-level summary of the characteristics of the language.
The following topics are covered in this chapter:
The Go programming language
Since the invention of the C language in the early 1970s by Dennis Ritchie at Bell Labs, the computing industry has produced many popular languages that are based directly on (or have borrowed ideas from) its syntax. Commonly known as the C-family of languages, they can be split into two broad evolutionary branches. In one branch, derivatives such as C++, C#, and Java have evolved to adopt a strong type system, object orientation, and the use of compiled binaries. These languages, however, tend to have a slow build-deploy cycle and programmers are forced to adopt a complex object-oriented type system to attain runtime safety and speed of execution:
In the other evolutionary linguistic branch are languages such as Perl, Python, and JavaScript that are described as dynamic languages for their lack of type safety formalities, use of lightweight scripting syntax, and code interpretation instead of compilation. Dynamic languages have become the preferred tool for web and cloud scale development where speed and ease of deployment are valued over runtime safety. The interpreted nature of dynamic languages means, however, they generally run slower than their compiled counterparts. In addition, the lack of type safety at runtime means the correctness of the system scales poorly as the application grows.
Go was created as a system language at Google in 2007 by Robert Griesemer, Rob Pike, and Ken Thomson to handle the needs of application development. The designers of Go wanted to mitigate the issues with the aforementioned languages while creating a new language that is simple, safe, consistent, and predictable. As Rob Pike puts it:
"Go is an attempt to combine the safety and performance of a statically-typed language with the expressiveness and convenience of a dynamically-typed interpreted language."
Go borrows ideas from different languages that came before it, including:
The remainder of this chapter will walk you through an introductory set of steps that will give you a preview of the language and get you started with building and running your first Go program. It is a precursor to the topics that are covered in detail in the remaining chapters of the book. You are welcome to skip to other chapters if you already have a basic understanding of Go.
Playing with Go
Before we jump head-first into installing and running Go tools on your local machine, let us take a look at the Go Playground. The creators of the language have made available a simple way to familiarize yourself with the language without installing any tools. Known as the Go Playground, it is a web-based tool, accessible from https://play.golang.org/, that uses an editor metaphor to let developers test their Go skills by writing code directly within the web browser window. The Playground gives its users the ability to compile and run their code on Google's remote servers and get immediate results as shown in the following screenshot:
The editor is basic, as it is meant to be used as a learning tool and a way to share code with others. The Playground includes practical features such as line numbers and formatting to ensure your code remains readable as it goes beyond a few lines long. Since this is a free service that consumes real compute resources, Google understandably imposes a few limitations on what can be done with Playground:
No IDE required
Besides the Go Playground, how is one supposed to write Go code anyway? Writing Go does not require a fancy Integrated Development Environment (IDE). As a matter of fact, you can get started writing your simple Go programs with your favorite plain text editor that is bundled with your OS. There are, however, Go plugins for most major text editors (and full-blown IDEs) such as Atom, Vim, Emacs, Microsoft Code, IntelliJ, and many others. There is a complete list of editors and IDE plugins for Go which can be found at https://github.com/golang/go/wiki/IDEsAndTextEditorPlugins.
Installing Go
To start programming with Go on your local machine you will need to install the Go Toolchain on your computer. At the time of writing, Go comes ready to be installed on the following major OS platforms:
The official installation packages are all available for 32-bit and 64-bit Intel-based architectures. There are also official binary releases that are available for ARM architectures as well. As Go grows in popularity, there will certainly be more binary distribution choices made available in the future.
Let us skip the detailed installation instructions as they will certainly change by the time you read this. Instead, you are invited to visit http://golang.org/doc/install and follow the directions given for your specific platform. Once completed, be sure to test your installation is working before continuing to use the following command:
$> go versiongo version go1.6.1 linux/amd64The previous command should print the version number, target OS, and the machine architecture where Go and its tools are installed. If you do not get an output similar to that preceding command, ensure to add the path of the Go binaries to your OS's execution PATH environment variable.
Before you start writing your own code, ensure that you have properly set up your GOPATH. This is a local directory where your Go source files and compiled artifacts are saved as you use the Go Toolchain. Follow the instructions found in https://golang.org/doc/install#testing to set up your GOPATH.
Source code examples
The programming examples presented throughout this book are available on the GitHub source code repository service. There you will find all source files grouped by chapters in the repository at https://github.com/vladimirvivien/learning-go/. To save the readers a few keystrokes, the examples use a shortened URL, that starts with golang.fyi, that points directly to the respective file in GitHub.
Alternatively, you can follow along by downloading and unzipping (or cloning) the repository locally. Create a directory structure in your GOPATH so that the root of the source files is located at $GOPATH/src/github.com/vladimirvivien/learning-go/.
Your first Go program
After installing the Go tools successfully on your local machine, you are now ready to write and execute your first Go program. For that, simply open your favorite text editor and type in the simple Hello World program shown in the following code:
package main import "fmt" func main() { fmt.Println("Hello, World!") }golang.fyi/ch01/helloworld.go
Save the source code in a file called helloworld.go anywhere inside your GOPATH. Then use the following Go command to compile and run the program:
$> go run helloworld.go Hello, World!If all goes well, you should see the message Hello, World! output on your screen. Congratulations, you have just written and executed your first Go program. Now, let us explore the attributes and characteristics of the Go language at a high level.
