Go Design Patterns for Real-World Projects

1087 Pages·2017·11.495 MB·english

by  Vladimir Vivien, Mario Castro Contreras, Mat Ryer

Go: Design Patterns for
Real-World Projects
Build production-ready solutions in Go using
cutting-edge technology and techniques
A course in three modules
BIRMINGHAM - MUMBAI
Go: Design Patterns for Real-World Projects
Copyright © 2017 Packt Publishing
Published on: June, 2017
Published by Packt Publishing Ltd.
Livery Place
35 Livery Street
Birmingham B3 2PB, UK.
ISBN 978-1-78839-055-2
www.packtpub.com
Preface
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 lets programmers write correct and predictable code using
concurrency idioms and a full-featured standard library.
What this learning path covers
Module 1, Learning Go programming, 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 module;
you would be able to create highly efficient programs that you can deploy over cloud.
Module 2, Go Design Patterns, will provide readers with a reference point to software
design patterns and CSP concurrency design patterns to help them build applications
in a more idiomatic, robust, and convenient way in Go.
The module starts with a brief introduction to Go programming essentials and
quickly moves on to explain the idea behind the creation of design patterns and
how they appeared in the 90's as a common "language" between developers to solve
common tasks in object-oriented programming languages. You will then learn how
to apply the 23 Gang of Four (GoF) design patterns in Go and also learn about CSP
concurrency patterns, the "killer feature" in Go that has helped Google develop
software to maintain thousands of servers.
With all of this the module will enable you to understand and apply design patterns
in an idiomatic way that will produce concise, readable, and maintainable software.
Module 3, Go Programming Blueprints - Second Edition, will show you how to leverage
all the latest features and much more. This module shows you how to build powerful
systems and drops you into real-world situations. You will learn to develop high-
quality command-line tools that utilize the powerful shell capabilities and perform
well using Go's in-built concurrency mechanisms. Scale, performance, and high
availability lie at the heart of our projects, and the lessons learned throughout this
module will arm you with everything you need to build world-class solutions. You
will get a feel for app deployment using Docker and Google App Engine. Each
project could form the basis of a start-up, which means they are directly applicable to
modern software markets.
What you need for this learning path
Module 1:
To follow the examples in this module, you will need Go version 1.6 or later. Go
supports architectures including AMD64, x386, and ARM running the following
operating systems:
• Windows XP (or later)
• Mac OSX 10.7 (or later)
• Linux 2.6 (or later)
• FreeBSD 8 (or later)
Module 2:
Most of the chapters in this module are written following a simple TDD approach,
here the requirements are written first, followed by some unit tests and finally
the code that satisfies those requirements. We will use only tools that comes with
the standard library of Go as a way to better understand the language and its
possibilities. This idea is key to follow the module and understanding the way that
Go solves problems, especially in distributed systems and concurrent applications.
Module 3:
To compile and run the code from this module, you will need a computer capable
of running an operating system that supports the Go toolset, a list of which can be
found at https://golang.org/doc/install#requirements
Appendix, Good Practices for a Stable Go Environment, has some useful tips to install
Go and set up your development environment, including how to work with the
GOPATH environment variable.
Who this learning path is for
Beginners to Go who are comfortable in other OOP languages like Java, C# or
Python will find this course interesting and beneficial.
Reader feedback
Feedback from our readers is always welcome. Let us know what you think about
this course—what you liked or disliked. Reader feedback is important for us as it
helps us develop titles that you will really get the most out of.
To send us general feedback, simply e-mail [email protected], and mention
the course's title in the subject of your message.
If there is a topic that you have expertise in and you are interested in either writing
or contributing to a course, see our author guide at www.packtpub.com/authors.
Customer support
Now that you are the proud owner of a Packt course, we have a number of things to
help you to get the most from your purchase.
Downloading the example code
You can download the example code files for this course from your account at
http://www.packtpub.com. If you purchased this course elsewhere, you can visit
http://www.packtpub.com/support and register to have the files e-mailed directly
to you.
You can download the code files by following these steps:
1. Log in or register to our website using your e-mail address and password.
2. Hover the mouse pointer on the SUPPORT tab at the top.
3. Click on Code Downloads & Errata.
4. Enter the name of the course in the Search box.
5. Select the course for which you're looking to download the code files.
6. Choose from the drop-down menu where you purchased this course from.
7. Click on Code Download.
You can also download the code files by clicking on the Code Files button on the
course's webpage at the Packt Publishing website. This page can be accessed by
entering the course's name in the Search box. Please note that you need to be logged
in to your Packt account.
Once the file is downloaded, please make sure that you unzip or extract the folder
using the latest version of:
• WinRAR / 7-Zip for Windows
• Zipeg / iZip / UnRarX for Mac
• 7-Zip / PeaZip for Linux
The code bundle for the course is also hosted on GitHub at https://github.com/
PacktPublishing/Go-Design-Patterns-for-Real-World-Projects. We also
have other code bundles from our rich catalog of books and videos available at
https://github.com/PacktPublishing/. Check them out!
Errata
Although we have taken every care to ensure the accuracy of our content, mistakes
do happen. If you find a mistake in one of our courses—maybe a mistake in the text
or the code—we would be grateful if you could report this to us. By doing so, you
can save other readers from frustration and help us improve subsequent versions
of this course. If you find any errata, please report them by visiting http://www.
packtpub.com/submit-errata, selecting your course, clicking on the Errata
Submission Form link, and entering the details of your errata. Once your errata are
verified, your submission will be accepted and the errata will be uploaded to our
website or added to any list of existing errata under the Errata section of that title.
To view the previously submitted errata, go to https://www.packtpub.com/books/
content/support and enter the name of the course in the search field. The required
information will appear under the Errata section.
Module 1: Learning Go Programming
Chapter 1: A First Step in Go
7
The Go programming language 8
Playing with Go 10
No IDE required 11
Installing Go 11
Source code examples 12
Your first Go program 12
Go in a nutshell 13
Functions 15
Packages 16
The workspace 16
Strongly typed 16
Composite types 17
The named type 18
Methods and objects 18
Interfaces 19
Concurrency and channels 20
Memory management and safety 21
Fast compilation 22
Testing and code coverage 22
Documentation 23
An extensive library 24
The Go Toolchain 25
Summary 25
Chapter 2: Go Language Essentials
26
The Go source file 27
Optional semicolon 29
Multiple lines 30
Go identifiers 32
The blank identifier 32
Muting package imports 32
Muting unwanted function results 33
Built-in identifiers 33
Types 33
Values 34
Functions 34
Go variables 34
Variable declaration 34
The zero-value 36
Initialized declaration 36
Omitting variable types 37
Short variable declaration 39
Restrictions for short variable declaration 40
Variable scope and visibility 40
Variable declaration block 42
Go constants 42
Constant literals 42
Typed constants 43
Untyped constants 43
Assigning untyped constants 44
Constant declaration block 45
Constant enumeration 46
Overriding the default enumeration type 47
Using iota in expressions 47
Skipping enumerated values 48
Go operators 49
Arithmetic operators 49
The increment and decrement operators 49
Go assignment operators 50
Bitwise operators 50
Logical Operators 51
Comparison operators 51
Operator precedence 52
Summary 52
Chapter 3: Go Control Flow
53
The if statement 53
The if statement initialization 57
Switch statements 57
Using expression switches 59
The fallthrough cases 60
Expressionless switches 62
Switch initializer 63
[ ii ]
Type switches 64
The for statements 66
For condition 66
Infinite loop 67
The traditional for statement 68
The for range 70
The break, continue, and goto statements 73
The label identifier 73
The break statement 73
The continue statement 74
The goto statement 75
Summary 76
Chapter 4: Data Types
77
Go types 77
Numeric types 80
Unsigned integer types 81
Signed integer types 81
Floating point types 82
Complex number types 82
Numeric literals 82
Boolean type 84
Rune and string types 84
The rune 85
The string 86
Interpreted and raw string literals 87
Pointers 88
The pointer type 89
The address operator 89
The new() function 91
Pointer indirection - accessing referenced values 92
Type declaration 93
Type conversion 94
Summary 96
Chapter 5: Functions in Go
97
Go functions 97
Function declaration 98
The function type 101
Variadic parameters 102
[ iii ]
Function result parameters 103
Named result parameters 104
Passing parameter values 105
Achieving pass-by-reference 106
Anonymous Functions and Closures 107
Invoking anonymous function literals 108
Closures 108
Higher-order functions 109
Error signaling and handling 110
Signaling errors 111
Error handling 114
The error type 114
Deferring function calls 115
Using defer 117
Function panic and recovery 117
Function panic 117
Function panic recovery 119
Summary 121
Chapter 6: Go Packages and Programs
122
The Go package 122
Understanding the Go package 122
The workspace 124
Creating a workspace 126
The import path 127
Creating packages 128
Declaring the package 129
Multi-File packages 130
Naming packages 131
Use globally unique namespaces 131
Add context to path 132
Use short names 132
Building packages 133
Installing a package 134
Package visibility 134
Package member visibility 135
Importing package 136
Specifying package identifiers 138
The dot identifier 139
The blank identifier 139
[ iv ]