Die Programmiersprache Go

Hallo!
Thorsten Ball
mrnugget / @thorstenball
Software Developer

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@thorstenball
Go
Go

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@thorstenball
Go
Go’s Erfinder
• Robert Griesemer (V8 Engine, HotSpot Java VM)
• Rob Pike (Plan 9 Unix, UTF-8)
• Ken Thompson (Unix, B, UTF-8)

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@thorstenball
Go
Ziele
• "It must work at scale, for large programs with large
numbers of dependencies, with large teams of
programmers working on them.”
• "It must be familiar, roughly C-like. [...] The need to get
programmers productive quickly”
• "It must be modern. [...] built in concurrency"

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@thorstenball
Go
Go
• 2007 - erste Entwürfe
• 2009 - erste Version veröffentlicht
• 2012 - Version 1.0 veröffentlicht
• 2015 - Version 1.4

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@thorstenball
Go
Go
• Kompiliert
• Statisch
• Garbage Collection
• Concurrency
• Schnell

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@thorstenball
Go
Wie sieht Go aus?

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@thorstenball
Go
Hello World
package main
import "fmt"
func main() {
fmt.Println("Hello World!")
}

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@thorstenball
Go
Funktionen
package main
import "fmt"
func SayHello(name string) {
fmt.Println("Hello " + name)
}
func main() {
SayHello("World!")
SayHello("Go!")
SayHello("flinc!")
}

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@thorstenball
Go
Variablen
package main
import "fmt"
var i int = 1
var name string = "Go"
func main() {
var x int = 2
var y = 3
z := 4
s := "bob"
fmt.Println(i, name, x, y, z, s)
}

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@thorstenball
Go
Flow-Control
package main
import "fmt"
func main() {
for i := 0; i < 10; i++ {
if i % 2 == 0 {
fmt.Println(i)
} else {
fmt.Println("no")
}
}
// while == for
sum := 1
for sum < 10 {
sum += sum
}
}

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@thorstenball
Go
Structs
package main
import "fmt"
type Person struct {
Age int
Name string
}
func main() {
var bob Person
bob.Age = 24
bob.Name = "Bob"
anna := Person{Age: 27, Name: "Anna"}
fmt.Printf("Name: %s, Age: %d\n", bob.Name, bob.Age)
fmt.Printf("Name: %s, Age: %d\n", anna.Name, anna.Age)
}

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@thorstenball
Go
Pointers!
package main
import "fmt"
type Person struct {
Name string
}
func SayName(p *Person) {
fmt.Println(p.Name)
}
func main() {
anna := &Person{Age: 27, Name: "Anna"}
SayName(anna)
}

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@thorstenball
Go
Programmieren mit Go

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@thorstenball
Go
Die Umgebung
• $GOPATH
• Source, Binary und Executable
• Normale Verzeichnisse, keine “magic”
• Verwaltung mit go-Tool

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@thorstenball
Go
$GOPATH
bin/
hello # command executable
outyet # command executable
pkg/
linux_amd64/
github.com/golang/example/
stringutil.a # package object
src/
github.com/golang/example/
.git/ # Git repository metadata
hello/
hello.go # command source
outyet/
main.go # command source
main_test.go # test source
stringutil/
reverse.go # package source
reverse_test.go # test source

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@thorstenball
Go
Tools
• Go hat viele Tools um mit Go-Code zu arbeiten
• Der Großteil ist in der Standard-Installation enthalten
• Tools sind sehr wichtig bei Go
• Keine zusätzlichen Installationen nötig

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@thorstenball
Go
go Tool
• go get
• go build
• go install
• go test
• go fmt
• go test -race
• go vet
• go tool pprof

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@thorstenball
Go
go fmt

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@thorstenball
Go
Standard Library
• Sehr groß
• Sehr gut gepflegt
• Der idiomatischste Go-Code (/usr/local/go/src)

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@thorstenball
Go
Standard Library
• net/http - HTTP-Server und Client
• io - I/O-Interfaces und Hilfsfunktionen
• fmt - Formattiertes IO (Printf, Println, Sprintf)
• flag - Command-Line Arguments
• database/sql - Grundgerüst für SQL-Treiber
• encoding/json - JSON-Parser
• html/template - HTML-Templating Engine
• …

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@thorstenball
Go
Packages

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@thorstenball
Go
Packages
package foobar
import "fmt"
func Hello() {
fmt.Println("Hello World!")
}

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@thorstenball
Go
Packages
package main
import "github.com/mrnugget/foobar"
func main() {
foobar.Hello()
}

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@thorstenball
Go
Packages
• GroßGeschriebene Namen werden exportiert
• kleinGeschriebene Namen werden nicht exportiert
• Kein Monkey-Patching

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@thorstenball
Go
Package-Management

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@thorstenball
Go
Testing
• Test-Framework ist mitgeliefert
• import “testing”
• foobar_test.go
• go test

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@thorstenball
Go
Testing
package foobar
import "testing"
func TestSayName(t *testing.T) {
result := SayName()
if result != "thorsten" {
t.Error("result is wrong")
}
}

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@thorstenball
Go
Keine Klassen, keine Vererbung
• Structs
• Types
• Methoden auf Structs/Types definierbar
• First-class functions!

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@thorstenball
Go
Concurrency

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@thorstenball
Go
goroutines
package main
import "fmt"
import "time"
func ThreeTimes(line string) {
for i := 0; i < 3; i++ {
time.Sleep(100 * time.Millisecond)
fmt.Println(line)
}
}
func main() {
go ThreeTimes("hello")
ThreeTimes("world")
}
// Output:
world
hello
world
hello
world

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@thorstenball
Go
Channels

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@thorstenball
Go
Channels
package main
import "fmt"
import "math/rand"
import "time"
func CalcNumber(results chan int) {
time.Sleep(100 * time.Millisecond)
results <- rand.Int() // blocking
}
func main() {
results := make(chan int)
go CalcNumber(results)
go CalcNumber(results)
num := <-results // blocking
fmt.Println(num)
num = <-results // blocking
fmt.Println(num)
}

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@thorstenball
Go
Wofür?

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@thorstenball
Go
Wofür?
• Web-Services
• Infrastruktur
• Server
• Command Line Tools

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@thorstenball
Go
Go wird eingesetzt von…
• Google
• Apple
• Microsoft
• Dropbox
• GitHub
• Shopify
• Soundcloud
• Heroku
• Tumblr
• 6Wunderkinder

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@thorstenball
Go
Go.

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@thorstenball
Go
Go lernen
• tour.golang.org
• golang.org/doc
• blog.golang.org
• Google “golang” (…)

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@thorstenball
Go
Danke

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Die Programmiersprache Go

Die Programmiersprache Go

Thorsten Ball

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