Go for Rubysts

This presentation tries to introduce people that are familiar to ruby with Go.

Transcript

1. Go for Rubysts Thiago Pradi RubyConf Argentina - 2013
2. whoami • Thiago Pradi • Brazilian! • Software Developer @ JobScore • Bachelor of Computer Science @ FURB • Octopus author / maintainer
3. Thiago was a happy Ruby developer...
5. that wanted to learn something new!
6. Why not a new language? ... ... Maybe Go!
7. Google trends - Golang
8. What is Go?
9. Go • Initially developed at Google • Created by Ken Thompson (Unix), Rob Pike (Plan 9), and Russ Cox (libtask) • Development started in 2007 • First release in 2009 (Fairly new!)
10. Go is an open source programming environment that makes it easy to build simple, reliable, and efficient software. Source: golang.org
11. Features • New • Concurrent • Compiled • Garbaged-collected • Simple & Fun!
12. Language focus • System programming • Networked / multi-core • Fast • Compatible with C • Best of static typed language and dynamic languages
13. Basic Concepts
14. package main
 
 import "fmt" 
 
 func main() {
 fmt.Println("Hello World")
 }

15. C-Like Syntax func main() {
 fmt.Printf("Animal with name %s and age %d", "Anaconda", 32)
 }

16. Compiled language
17. Typesystem
18. Strong types func main() { var str string var value int str = "abc" value = 123 str + value }
19. Static Typed // types.go func main() {
 var a string
 
 a = 123
 }
20. with dynamic casting package main
 import ( "fmt" )
 
 func main() {
 a := 123
 fmt.Printf("Value of a: %d", a)
 }

21. User defined types package main;
 
 type Animal struct {
 Name string
 Age int
 }
 
 func main() {
 var anaconda Animal
 }

22. Compiler • Uses GCC as back end • Checks for unused packages and variables • Checks types and return values
23. Go tools • go fmt -> format your source code (cool!) • go get -> manage and install your dependencies • go build / run -> compile and run your program • go test -> run your tests
24. Organizing code package string_processing;
 
 func Process(str string) {
 // Code code code }
 package main 
 import "string_processing"
 func main() {
 string_processing.Process("foobar")
 }
25. Workspace • The default way to organize code in Go • Build to work with OpenSource repositories • Directories src, bin and pkg
27. Encoding • Source code: UTF-8 • Strings: UTF-8
28. Comparing it to Ruby..
29. Disclaimer
30. Object Orientation • Ruby uses classes / methods • Golang uses Interfaces, adding methods to data structures.
31. Objects in Ruby • Ruby Object model • Module / Class with methods • Support for inheritance and composition • Everything is an object
32. class Animal attr_accessor :name def initialize(name) self.name = name end def say_something puts "HEY HEY" end end ! a = Animal.new("Duck") a.say_something
33. Objects in Go • No inheritance • Data types to define content • Methods define the operations • Interfaces define the behavior of the “object” (data type)
34. package main import "fmt" type Animal struct { Name string } ! func (a *Animal) SaySomething() { fmt.Println("HEY HEY") } ! func main() { a := new(Animal) a.Name = "Duck" a.SaySomething() }
35. Error Handling • Ruby uses Exceptions, with begin / rescue / ensure • Golang use return values with error code (!!!)
36. Error handling - Ruby • Errors inherit from Exception class • Flow control with begin / rescue / ensure • Don’t need to treat every exception
37. file = File.open("/tmp/mel.txt", "w") ! begin # does some file processing rescue puts "Failed to process" ensure file.close end
38. Error Handling - Go • No exceptions • Errors should implement “Error” interface • Erros should be returned as additional value • Every error should be treated (unless you want to do a “Gambiarra”)
39. Off-topic: Gambiarra
40. func main() { fmt.Println("Starting MEL server") ! listener, err := net.Listen("tcp", "0.0.0.0:2653") ! if err != nil { fmt.Println("Error starting the server") os.Exit(1) } }
41. defer / panic / recover • Defer is compared to “ensure” in ruby • Panic / recover are similar to exception, but only should be used for internal APIs, never for external APIs. • Panic is used for runtime errors, like array out of bound
42. func EchoFunction(connection net.Conn, ss *command_parser.ServerStorage) { defer connection.Close() ! buf := make([]byte, 1024) n, err := connection.Read(buf) // Heavy logic }
43. func main() { PanicFunction() fmt.Println("This will not be printed") } ! func PanicFunction() { defer func() { fmt.Println("Called defer function") }() panic("PANIC PANIC PANIC") fmt.Println("This will not be printed") }
44. func main() { PanicFunction() fmt.Println("This will be printed") } ! func PanicFunction() { defer func() { if e := recover(); e != nil { fmt.Printf("Recovered from %s \n", e) } }() panic("PANIC PANIC PANIC") fmt.Println("This will not be printed") }
45. Concurrency • Ruby -> Threads / Fibers / EventPool / Actors • Go -> Goroutines
46. Concurrency - Ruby • Threads (with shared memory) • Fibers • EventMachine (Event loop / Reactor pattern) • Celluloid (Actor based)
47. require 'net/http' ! content = [] ! thread = Thread.new do uri = URI("http://triremi.com/") content << Net::HTTP.get(uri) end ! thread.join
48. Concurrency - Go • Goroutines! • Lightweight thread implementation • Communications between goroutines using channels • Managed by the Go Scheduler • Mapped to a few different OS processes
49. for { connection, err := listener.Accept() ! if err != nil { fmt.Println("Error accepting the socket") os.Exit(2) } ! EchoFunction(connection, ss) }
50. for { connection, err := listener.Accept() ! if err != nil { fmt.Println("Error accepting the socket") os.Exit(2) } ! go EchoFunction(connection, ss) }
51. import "fmt" ! func main() { messages := make(chan string) ! go PingFunction(messages) ! msg := <-messages ! fmt.Println(msg) } ! func PingFunction(messages chan string) { messages <- "ping" }
52. // Make the channel with the number of connections channels := make(chan ChannelResult, number_of_connections) ! // Start the request in a new goroutine go makeRequest(address, start_byte, end_byte, out, channels) ! //Wait for the result of the goroutine in the channel for(loop_var < number_of_connections) { chan_res := <-channels // Process the result and save to the file }
53. Testing • Ruby has a built in framework (Test::Unit) and a lot of alternatives • Go also has a default framework for testing, and some early-stages alternatives
54. Testing in Ruby • Lots of frameworks: Test::Unit, rspec, MiniTest, Bacon… • Frameworks with lots of assertions and pre- defined macros • Easy to describe behavior (BDD) • Everyone tests.. (RIGHT?)
55. require "spec_helper" ! describe Octopus::Model do describe "#using method" do it "should return self" do User.using(:canada).should be_a(Octopus::ScopeProxy) end end end
56. Testing in Go • Light framework with the language, with a few new options • Don’t come with assertions / macros • Tests have the same package as the application code • Tests stay in the same directory of the application code
57. package command_parser; ! import ( “testing" ) ! func Test_parseSetCommand (t *testing.T) { ss := new(ServerStorage) ! str := ss.ParseCommand("SET thiagopradi valor") ! if ss.Dict["thiagopradi"] != "valor" { t.Error("failed to set thiagopradi key") } } }
58. But, what about some real use cases?
59. Companies • Google (dl.google.com, youtube) • SoundCloud • Heroku • CloudFlare • Ubuntu
60. Open Source • https://github.com/youtube/vitess - Process and tools for scaling MySQL • https://github.com/dotcloud/docker - Open Source application container engine • https://github.com/burke/zeus - Rails preloader
61. Mine • YADM - Yet another download manager (https://github.com/tchandy/yadm) • Brainfuck compiler (https://github.com/ tchandy/bf_compiler_go) • Mel - key-value database (https://github.com/ tchandy/mel)
62. Wrapping up… • Cool language • Concurrent and networked • Benefits from both dynamic and static languages • Modern • Give it a try!
63. One more thing..
64. GOLang!
65. GOLang!
66. Thank you! • www.thiagopradi.net • twitter.com/thiagopradi • thiago.pradi@gmail.com