Introduction to Go

An introduction to Go focused on teaching Bootcamp students learning Ruby the basics along with advantages and disadvantages.

Transcript

1. Twitter: @tpryan Introduction to Go Terry Ryan Developer Advocate
2. @tpryan What is Go How to Write Go Why use Go (and why not) 1 2 3 Agenda
3. @tpryan Who are you?
4. Twitter: @tpryan What is Go?
5. @tpryan • Developed at Google • Open Source • Compiled What is Go? Go is a programming language
6. @tpryan Wait! What the hell is that thing?
7. @tpryan What is Go? The Gopher https://blog.golang.org/gopher
8. @tpryan • Compiled • Garbage collected • Strongly typed • Statically typed • C syntax • Simple • Built to use multiple processors • Tools design for remote packages • Testing built in Language focused on Software engineering What is Go? Go features
9. Twitter: @tpryan How to Write Go Let’s see some code already
10. @tpryan 02_hellowworld/main.go package main import "fmt" func main() { var s string = "Hello World" fmt.Printf("%s\n", s) } Hello World How to Write Go
11. @tpryan Command Line go run main.go Hello World How to Write Go
12. Twitter: @tpryan Section Slide Template Option 2 Put your subtitle here. Feel free to pick from the handful of pretty Google colors available to you. Make the subtitle something clever. People will think it’s neat. Variables
13. @tpryan Type inference var s string = "Hello World" s := "Hello World" Hello World How to Write Go
14. @tpryan main.go package main import "fmt" func main() { s := "Hello World" fmt.Printf("%s\n", s) } Hello World How to Write Go
15. @tpryan • bool • string • int int8 int16 int32 int64 • uint uint8 uint16 uint32 uinint 64 uintptr • byte (uint8) • rune (int32) • float32 float 64 • complex64 complex128 What is Go? Go variables
16. @tpryan • Array - finite, ordered collection of elements ◦ users := [4]string What is Go? Go arrays vs slices 4 ? • Slice - points to an array, allows for more dynamic operations ◦ users :=[]strings
17. @tpryan Array Literal users := [5]string{"adrock", "grwilson", "tpryan", "krhoyt", "ragefest", } Array How to Write Go
18. @tpryan Slice Literal users := []string{"adrock", "grwilson", "tpryan", "krhoyt", "ragefest", } users.append("campoy") Slice How to Write Go
19. @tpryan Slice Literal g := []string{"你好世界", "Hello wereld", "Hello world", "Bonjour monde", "Hallo Welt", "γειά σου κόσμος", "Ciao mondo", "こんにちは世界", "여보세요 세계", "Olá mundo", "Здравствулте мир", "Hola mundo"} Hello World How to Write Go
20. @tpryan 03_helloworld/main.go package main import ( "fmt" "math/rand" "time" ) func main() { g := []string{"你好世界", … } rand.Seed(time.Now().Unix()) l := len(g) i := rand.Intn(l - 1) fmt.Printf("%s\n", greetings[i]) } Hello World How to Write Go
21. Twitter: @tpryan Section Slide Template Option 2 Put your subtitle here. Feel free to pick from the handful of pretty Google colors available to you. Make the subtitle something clever. People will think it’s neat. Input
22. @tpryan Command Line go run main.go -lang 2 Hello World How to Write Go
23. @tpryan 04_helloworld/main.go package main import ( "flag" "fmt" "log" "os" "strconv" ) func main() { i := flag.Int("lang", 0, " a number between 0 and 11") flag.Parse() a := []string{"你好世界", … } fmt.Printf("%s\n", a[i]) } Hello World How to Write Go
24. Twitter: @tpryan Section Slide Template Option 2 Put your subtitle here. Feel free to pick from the handful of pretty Google colors available to you. Make the subtitle something clever. People will think it’s neat. Error Handling Part 1
25. @tpryan Error Handling if *i >= len(g) { log.Fatalf("%d is not valid, please choose between 0 - %d", *i, len(a)) } Errors How to Write Go
26. Twitter: @tpryan Section Slide Template Option 2 Put your subtitle here. Feel free to pick from the handful of pretty Google colors available to you. Make the subtitle something clever. People will think it’s neat. Finishing up the Program
27. @tpryan Command Line go run main.go -lang English Hello World How to Write Go
28. @tpryan Map Literal greetings := map[string]string{ "Chinese": "你好世界", "Dutch": "Hello wereld", "English": "Hello world", "French": "Bonjour monde", "German": "Hallo Welt", "Greek": "γειά σου κόσμος", "Italian": "Ciao mondo", "Japanese": "こんにちは世界", "Korean": "여보세요 세계", "Portuguese": "Olá mundo", "Russian": "Здравствулте мир", "Spanish": "Hola mundo", } Hello World How to Write Go
29. @tpryan main.go func main() { l := flag.String("lang", "English", "a language in which to get greeting.") flag.Parse() g := map[string]string{"Chinese":"你好世界", … } if r, ok := g[*l]; ok { fmt.Printf("%s\n", r) } else { log.Fatal("The language you selected is not valid.") } } Hello World How to Write Go
30. @tpryan Wait! What the hell is that thing?
31. @tpryan main.rb greet_list = { 'Chinese' => "你好世界", … } lang = ARGV[0] lang = "English" if lang == nil response = greet_list[lang] if response == nil puts "The language you selected is not valid." else puts response end Hello World How to Write Go
32. @tpryan main.go func main() { lang := flag.String("lang", "English", "a language in which to get greeting.") flag.Parse() greet_list := map[string]string{"Chinese":"你好世界", … } if result, ok := greet_list[*lang]; ok { fmt.Printf("%s\n", result) } else { log.Fatal("The language you selected is not valid.") } } Hello World How to Write Go
33. @tpryan Why are variables in Go so short?
34. @tpryan We hate you and we hate things that are good. – Creators of Go
35. @tpryan Variable names in Go should be short rather than long. This is especially true for local variables with limited scope. Prefer c to lineCount. Prefer i to sliceIndex. https://github.com/golang/go/wiki/CodeReviewComments#variable-names
36. @tpryan "5-week-old Golden Retriever puppy" by Keagiles - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons - http: //commons.wikimedia.org/wiki/File:5-week-old_Golden_Retriever_puppy.jpg#/media/File:5-week-old_Golden_Retriever_puppy.jpg Go - d Ruby - dog Java - GoldenRetrieverWithASadFace
37. @tpryan main.go func main() { l := flag.String("lang", "English", "a language in which to get greeting.") flag.Parse() g := map[string]string{"Chinese":"你好世界", … } if r, ok := g[*l]; ok { fmt.Printf("%s\n", r) } else { log.Fatal("The language you selected is not valid.") } } Hello World How to Write Go
38. @tpryan main.go if r, ok := g[*l]; ok { fmt.Printf("%s\n", r) } else { log.Fatal("The language you selected is not valid.") } Hello World How to Write Go
39. @tpryan main.go r, ok := g[*l] if ok { fmt.Printf("%s\n", r) } else { log.Fatal("The language you selected is not valid.") } Hello World How to Write Go
40. @tpryan main.go result, keyexists? := greeting[*language] if keyexists? { fmt.Printf("%s\n", result) } else { log.Fatal("The language you selected is not valid.") } Hello World How to Write Go
41. @tpryan main.go if result, keyexists? := greeting[*language]; keyexists? { fmt.Printf("%s\n", result) } else { log.Fatal("The language you selected is not valid.") } Hello World How to Write Go
42. @tpryan main.go if r, ok := g[*l]; ok { fmt.Printf("%s\n", r) } else { log.Fatal("The language you selected is not valid.") } Hello World How to Write Go
43. @tpryan main.go func main() { l := flag.String("lang", "English", "a language in which to get greeting.") flag.Parse() g := map[string]string{"Chinese":"你好世界", … } if r, ok := g[*l]; ok { fmt.Printf("%s\n", r) } else { log.Fatal("The language you selected is not valid.") } } Hello World How to Write Go
44. Twitter: @tpryan Section Slide Template Option 2 Put your subtitle here. Feel free to pick from the handful of pretty Google colors available to you. Make the subtitle something clever. People will think it’s neat. Tooling Part 1
45. @tpryan • All Go projects happen in workspaces • All Go workspaces have 3 parts: ◦ src ◦ bin ◦ pkg • Most everything happens in src ◦ github.com/username/project • Set folder that contains src, bin, pkg to GOPATH ◦ export GOPATH=$HOME/go What is Go? Go Path
46. Twitter: @tpryan Section Slide Template Option 2 Put your subtitle here. Feel free to pick from the handful of pretty Google colors available to you. Make the subtitle something clever. People will think it’s neat. Package
47. @tpryan helloworld.go package helloworld import "errors" var greetings = map[string]string{"Chinese": "你好世界", … } func Greet(language string) (string, error) { if r, ok := greetings[language]; ok { return r, nil } else { return "", errors.New("The language you selected is not valid.") } } Hello World How to Write Go
48. @tpryan main.go package main import ( "fmt" "log" "os" "github.com/tpryan/gosamples/helloworld" ) Hello World How to Write Go That’s why GOPATH matters
49. Twitter: @tpryan Section Slide Template Option 2 Put your subtitle here. Feel free to pick from the handful of pretty Google colors available to you. Make the subtitle something clever. People will think it’s neat. Error Handling Part 2
50. @tpryan Error Handling func Greet(language string) (string, error) { if r, ok := greetings[language]; ok { return r, nil } else { return "", errors.New(errorNotFound) } } Hello World How to Write Go
51. @tpryan error handling func main() { l := flag.String("lang", "English", "a language in which to get greeting.") flag.Parse() greet, err := helloworld.Greet(*l) if err != nil { log.Fatal(err) } fmt.Printf("%s\n", greet) } Hello World How to Write Go
52. @tpryan main.go cont func main() { l := flag.String("lang", "English", "a language in which to get greeting.") flag.Parse() greet, err := helloworld.Greet(*l) if err != nil { if strings.Contains(err.Error(), helloworld.ErrorNotFound) { listLanguages() } else { log.Fatal(err) } } fmt.Printf("%s\n", greet) } Hello World How to Write Go
53. Twitter: @tpryan Section Slide Template Option 2 Put your subtitle here. Feel free to pick from the handful of pretty Google colors available to you. Make the subtitle something clever. People will think it’s neat. What’s Next
54. @tpryan
55. @tpryan
56. @tpryan helloworld.go package helloworld import "errors" var greetings = map[string]string{"Chinese": "你好世界", … } func Greet(language string) (string, error) func Langauges() []string Hello World How to Write Go
57. @tpryan main.go package main import ( "encoding/json" "errors" "fmt" "log" "net/http" "github.com/tpryan/gosamples/helloworld" ) func main() { http.HandleFunc("/get", HandleGet) http.HandleFunc("/list", HandleList) log.Print(http.ListenAndServe(":8080", nil)) } Hello World How to Write Go
58. @tpryan main.go func main() { http.HandleFunc("/get", HandleGet) http.HandleFunc("/list", HandleList) log.Print(http.ListenAndServe(":8080", nil)) } Hello World How to Write Go
59. @tpryan main.go cont func HandleList(w http.ResponseWriter, r *http.Request) { list := helloworld.Langauges() js, err := json.Marshal(list) if err != nil { handleError(w, err) return } sendJSON(w, string(js)) } Hello World How to Write Go
60. @tpryan main.go cont func handleError(w http.ResponseWriter, err error) { http.Error(w, err.Error(), http.StatusInternalServerError) log.Print(err) } func sendJSON(w http.ResponseWriter, content string) { w.Header().Set("Content-Type", "application/json") fmt.Fprint(w, content) } Hello World How to Write Go
61. @tpryan main.go cont func HandleGet(w http.ResponseWriter, r *http.Request) { lang := r.FormValue("language") greet, err := helloworld.Greet(lang) if err != nil { handleError(w, err) return } sendJSON(w, greet) } Hello World How to Write Go
62. Twitter: @tpryan Section Slide Template Option 2 Put your subtitle here. Feel free to pick from the handful of pretty Google colors available to you. Make the subtitle something clever. People will think it’s neat. Concurrency
63. Twitter: @tpryan Section Slide Template Option 2 Put your subtitle here. Feel free to pick from the handful of pretty Google colors available to you. Make the subtitle something clever. People will think it’s neat. Tooling Part 2
64. @tpryan Command Line go fmt main.go Formatting Code How to Write Go
65. @tpryan Command Line go build main.go Building executable How to Write Go
66. @tpryan Command Line go test github.com/tpryan/gosamples/helloworld Testing executable How to Write Go
67. @tpryan Command Line go get github.com/gorilla/rpc Getting remote packages How to Write Go
68. Twitter: @tpryan Why use Go (and why not) Shouldn’t you just use it for everything?
69. @tpryan Task 1 Get articles from Wordpress MySQL Flatten into HTML Files Write to Disk
70. @tpryan export.go textout/scripts/test.sh 1 Executing ruby test 0.355 Executing php test 0.371 Executing go test 0.085 Publish Static Data How to Write Go
71. @tpryan export.go textout/scripts/test.sh 10 Executing ruby test 0.654 Executing php test 0.803 Executing go test 0.290 Publish Static Data How to Write Go
72. @tpryan export.go textout/scripts/test.sh 100 Executing ruby test 5.659 Executing php test 5.655 Executing go test 2.866 Publish Static Data How to Write Go
73. @tpryan export.go textout/scripts/test.sh 1000 Executing ruby test 55.812 Executing php test 63.783 Executing go test 72.416 Publish Static Data How to Write Go
74. @tpryan Task 2 Get Airport Latitude and Longitude Data Compute Distance between 2 Cities using Haversine Formula Write to Disk
75. @tpryan calc.rb def deg2rad(deg) deg * Math::PI / 180 end def getDistance(lat1, lon1, lat2, lon2) earth_radius = 3963 # in miles dLat = deg2rad(lat2 - lat1) dLon = deg2rad(lon2 - lon1) a = Math.sin(dLat/2)*Math.sin(dLat/2) + Math.cos(deg2rad(lat1))*Math.cos(deg2rad(lat2))*Math.sin(dLon/2)*Math.sin(dLon/2) c = 2 * Math.asin(Math.sqrt(a)) d = earth_radius * c end Haversine formula Why use Go (and why not)
76. @tpryan calc.go calc/scripts/test.sh 1 Executing ruby test 0.084 Executing php test 0.123 Executing go test 0.009 Number Crunching How to Write Go
77. @tpryan calc.go calc/scripts/test.sh 1000 Executing ruby test 0.105 Executing php test 0.128 Executing go test 0.017 Number Crunching How to Write Go
78. @tpryan calc.go calc/scripts/test.sh 1000000 Executing ruby test 40.081 Executing php test 65.140 Executing go test 12.170 Number Crunching How to Write Go
79. @tpryan Task 3 Get password from Randomly Generated list Test if password conforms to rules Include a dictionary check Pa$$w0rdCh3ck
80. @tpryan calc.rb FAIL_EMPTY if candidate.length == 0 FAIL_MIN if candidate.length < MIN_LENGTH FAIL_MAX if candidate.length > MAX_LENGTH FAIL_UPPER unless candidate =~ /[A-Z]/ FAIL_LOWER unless candidate =~ /[a-z]/ FAIL_NUMBER unless candidate =~ /[0-9]/ FAIL_SPECIAL unless candidate =~ /[#{SPECIAL}]/ word = hashMatch(candidate) FAIL_DICTIONARY if word.length > 0 SUCCESS Password Psuedo Code Why use Go (and why not)
81. @tpryan Method 1 Pa$$w0rdCh3ck "AALII", "AALIIS", "AALS", "AARDVARK", "AARDVARKS", "AARDWOLF", "AARDWOLVES", "AARGH", "AARRGH", "AARRGHH", "AAS", "AASVOGEL", "AASVOGELS", "AB", Bruteforce
82. @tpryan password.go password/scripts/test.sh 1 bruteforce Executing ruby test 1.678 Executing php test 0.409 Executing go test 0.117 Password Testing How to Write Go
83. @tpryan password.go password/scripts/test.sh 100 bruteforce Executing ruby test 4.157 Executing php test 7.024 Executing go test 0.446 Password Testing How to Write Go
84. @tpryan password.go password/scripts/test.sh 1000 bruteforce Executing ruby test 28.383 Executing php test 71.505 Executing go test 4.069 Password Testing How to Write Go
85. @tpryan Method 2 Pa$$w0rdCh3ck "AALII", "AALIIS", "AALS", "AARDVARK", "AARDVARKS", "AARDWOLF", "AARDWOLVES", "AARGH", "AARRGH", "AARRGHH", "AAS", "AASVOGEL", "AASVOGELS", "AB", Hash "Pa$$", "a$$w", "$$w0", "$w0r", "w0rd", "0rdC", "rdCh", "dCh3", "Ch3c", "h3ck", "Pa$$w", "a$$w0", "$$w0r", "$w0rd",
86. @tpryan password.go password/scripts/test.sh 1 hash Executing ruby test 1.830 Executing php test 0.318 Executing go test 0.097 Password Testing How to Write Go
87. @tpryan password.go password/scripts/test.sh 100 hash Executing ruby test 1.848 Executing php test 0.318 Executing go test 0.095 Password Testing How to Write Go
88. @tpryan password.go password/scripts/test.sh 1000 hash Executing ruby test 1.888 Executing php test 0.328 Executing go test 0.107 Password Testing How to Write Go
89. @tpryan Use Go for ALL THE THINGS!!!! – That guy from Google
90. @tpryan Consider using Go when you run into one of these problems – That guy from Google
91. Twitter: @tpryan Conclusions Go forth and… (Crap, Go leads to a lot of puns. )
92. @tpryan Use Golang for searches
93. @tpryan • http://golang.org/ • http://www.sitepoint.com/go-rubyists/ • https://blog.engineyard.com/2014/intro-to-go-rubyists • https://github.com/basti1302/go-lang-cheat-sheet Helpful Links Conclusions
94. Twitter: @tpryan Thank you! Thank you! terrenceryan.com twitter.com/tpryan http://bit.ly/tpryan-go All Code in presentation is licensed under Apache: https://github.com/tpryan/SharedCode/ This work is licensed under a Creative Commons Attribution 2.0 Generic License.