Slides from the workshop at KCDC

1. Learning Go From Hello
World to Web Service
Eric Potter
Sweetwater

2. Learning Go From Hello
World to Web Service
Eric Potter
Sweetwater

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4. Learning Go From Hello
World to Web Service
Eric Potter
Sweetwater

5. Agenda
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1:00 Intro, Background, Tooling, Basic Syntax
1:30 Exercises
2:00 Arrays / Slices, Types / Interfaces
2:30 Exercises
3:00 Go Routines
3:30 Exercises
4:00 Web Services
4:30 Exercises

6. Background
Before we go
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7. Creators
Rob Pike
• Worked at Bell
Labs and Google
• co-creator of
UTF-8
Ken Thompson
• Designed and
implemented the
original Unix
Robert Griesemer
• Worked on
Google's V8
JavaScript engine
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8. Fast
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10. Tools
All systems go
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11. Installation
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12. Go CLI
• go run
• go build
• go mod init
• go test
• go get
• go fmt
• etc
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13. IDEs
VS Code GoLand ($)
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14. Hello World
Demo
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15. Hello World
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16. Imports
Single Multiple
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17. Types
Go your own way
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18. Basic Types
• bool
• string
• int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64
• rune // alias for int32 that represents a Unicode code point
• float32, float64
• complex64, complex128
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19. Variable Declaration
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20. Syntax
Let it go
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21. Terse
; ( )
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22. Notable Omissions
++i
do {}
while
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23. Function Syntax
C#
public <returnType> <name> (<args>)
Go
func <name> (<args>) <returnType>
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24. Fizz Buzz
Demo
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25. Fizz Buzz
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26. Questions
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27. Exercise 1
Euler 1
1) If we list all the natural numbers below 10 that are multiples of 3
or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
Find the sum of all the multiples of 3 or 5 below 1000.
2) The Sine value for 2 is positive and the value for 5 is negative.
Print the sum of the positive sine values from the input between 0
and 10. (hint import “math” and use math.Sin)
If you get done, try Euler 2 (https://projecteuler.net/problem=2)
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28. Euler 1
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30. Arrays
Go home
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31. Declaring Arrays
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32. Accessing Array Elements
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34. Iterate over an Array
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35. The size is part of the type
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36. Slices
Go home
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38. Dynamic Sizing
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39. Ranges
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40. Classes
Go home
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41. Classes
Go home
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Packages & Structs

42. Defining a Struct
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45. Associating Functions with Structs
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46. Interfaces
Go home
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47. Defining an Interface
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48. Checkerboard demo
Demo
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49. Questions
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50. Exercise 2
Create a GIF
Clone this repo: https://github.com/pottereric/GoGifBuilder
Using the image/gif and image/color packages, create a gif of a
checker board.
Using the same libraries, create an animated gif of a sine wave.
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51. Concurrency
You go your way,
I’ll go mine
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52. Concurrent Functions
Demo
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54. Channels
Go change the
channel
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55. TextEntryWithTimeout
Demo
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56. TextEntryWithTimeout
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57. WaitGroups
Go wait in the corner
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59. Questions
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60. Exercise 3
Create a GIF Concurrently
Modify your code that creates a sine wave gif to create the file
concurrently while the user enters the output file name.
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63. Web Services
Go on
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64. net/http Package
• The core functionality is in a standard library.
• There are packages like gin that provide structure.
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65. net/http
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66. net/http
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67. Data Access
Go get it
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68. database/sql
• Go uses a driver and plugin model.
• There are larger frameworks like Gorm
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69. database/sql
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70. Questions
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71. Exercise 4
Web Services
Create a webservice that returns the sine of a given number.
Create a webservice that returns your sine wave GIF
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72. Thank you
Eric Potter • @pottereric •
HumbleToolsmith.com
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