Golang

# Histoire

# Histoire

Bell Labs

Rob Pike

Google V8, JVM

Robert Griesemer

Bell Labs, B, Unix

Ken Thompson

# Histoire

# Histoire

Go gopher

# Caractéristiques

# Caractéristiques

# Caractéristiques

# Hello World

package main

# Hello World

package main

func main() {
}

# Hello World

package main

import "fmt"

func main() {
	fmt.Printf("Hello World!\n")
}

# Hello World

package main

import "fmt"

func main() {
	fmt.Printf("Hello World!\n")
}

$> go run main.go
Hello World!

$> go build main.go
$> ls
main main.go
$> ./main
Hello World!

# Variables

package main

import "fmt"

func main() {
    name := "Gopher"
    fmt.Printf("Hello %s\n", name)
}

package main

import "fmt"

func main() {
    var name string = "Gopher"
    fmt.Printf("Hello %s\n", name)
}

# Variables

package main

import "fmt"

func main() {
    var name string
    fmt.Printf("Hello world\n")
}

$> go run main.go
# command-line-arguments
./main.go:6:6: name declared but not used

# Variables

Boolean	bool
Chaine de caractère	string
Entiers	int int8 int16 int32 int64 uint uint8 uint16 uint32 uint64 uintptr
Data	byte (uint8)
Unicode	rune
Nombre non entier	float32 float64
Nombre complexes	complex64 complex128

# Conditions

package main

import "fmt"

func main() {
	health := 100
	if health <= 0 {
		fmt.Printf("You died\n")
	}
}

# Conditions

package main

import "fmt"

func main() {
	health := 100
	if health <= 0 {
		fmt.Printf("You died\n")
	} else {
		fmt.Printf("Keep going\n")
	}
}

# Conditions

package main

import "fmt"

func main() {
	if health := 100; health <= 0 {
		fmt.Printf("You died\n")
	} else {
		fmt.Printf("Keep going\n")
	}
}

# Conditions

package main

import (
	"fmt"
	"math/rand"
	"time"
)

func main() {
	s1 := rand.NewSource(time.Now().UnixNano())
	r1 := rand.New(s1)

	switch value := r1.Intn(10); value {
	case 5:
		fmt.Printf("You are in luck, 5!\n")
	case rand.Intn(10):
		fmt.Printf("You are in luck, same int twice in a row!\n")
	default:
		fmt.Printf("You lost %d\n", value)
	}
}

# Loops

# Loops

package main

import "fmt"

func main() {
	for i := 0; i < 10; i++ {
		fmt.Printf("%d\n", i)
	}
}

# Loops

package main

import (
	"fmt"
)

func main() {
	i := 0
	for i < 10 {
		fmt.Printf("%d\n", i)
		i++
	}
}

# Loops

package main

import (
	"fmt"
)

func main() {
	i := 0
	for {
		fmt.Printf("%d\n", i)
		i++
	}
}

# Loops

package main

import (
	"fmt"
)

func main() {
	users := [...]string{"Foo", "Bar"}

	for _, user := range users {
		fmt.Printf("%s\n", user)
	}
}

# Return values

package main

import (
	"fmt"
)

func foo() {
}

func main() {
	fmt.Printf("%s\n", foo())
}

# Return values

package main

import (
	"fmt"
)

func foo() {
	return "Bar"
}

func main() {
	fmt.Printf("%s\n", foo())
}

# Return values

package main

import (
	"fmt"
)

func foo() string {
	return "Bar"
}

func main() {
	fmt.Printf("%s\n", foo())
}

# Return values

package main

import (
	"fmt"
)

func foo(a int, b int) (total int) {
	total = a + b
	return
}

func main() {
	fmt.Printf("%d\n", foo(1, 4))
}

# Return values

# Return values

package main

import (
	"errors"
	"fmt"
)

func foo(a int, b int) (int, error) {
	if b == 0 {
		return 0, errors.New("Unable to divide by 0")
	}
	return a / b, nil
}

func main() {
	result, err := foo(5, 2)
	if err != nil {
		panic(err)
	}
	fmt.Printf("%d\n", result)
}

# Modules

// foo/bar.go
package main

import (
	"fmt"
)

func bar() {
	fmt.Printf("Hello World\n")
}

// main.go
package main

func main() {
}

# Modules

// foo/bar.go
package main

import (
	"fmt"
)

func bar() {
	fmt.Printf("Hello World\n")
}

// main.go
package main

import "demo/foo"

func main() {
	
}

# Modules

// foo/bar.go
package main

import (
	"fmt"
)

func bar() {
	fmt.Printf("Hello World\n")
}

// main.go
package main

import "demo/foo"

func main() {
	foo.bar()
}

$> go run main.go
# command-line-arguments
./main.go:6:6: undefined: foo.bar

# Modules

// foo/bar.go
package main

import (
	"fmt"
)

func Bar() {
	fmt.Printf("Hello World\n")
}

// main.go
package main

import "demo/foo"

func main() {
	foo.Bar()
}

$> go run main.go
Hello World

# Modules

// foo/bar.go
package main

import (
	"fmt"
)

var Baz string

func Bar() {
	fmt.Printf("Hello World\n")
}

// main.go
package main

import "demo/foo"

func main() {
	foo.Bar()
}

$> go run main.go
Hello World

# Structs

package main

type Character struct {
	health uint
}

func main() {
	
}

# Structs

package main

type Character struct {
	health int
}

func (character Character) isAlive() bool {
	return character.health > 0
}

func (character Character) damage(damages int) {
	character.health -= damages
}
 
func main() {
	
}

# Structs

package main

import "fmt"

type Character struct {
	health int
}

func (character Character) isAlive() bool {
	return character.health > 0
}

func (character Character) damage(damages int) {
	character.health -= damages
}

func main() {
	character := Character{health: 100}
	character.damage(50)
	fmt.Printf("Character have %d health points\n", character.health)
}

# Structs

package main

import "fmt"

type Character struct {
	health int
}

func (character Character) isAlive() bool {
	return character.health > 0
}

func (character *Character) damage(damages int) {
	character.health -= damages
}

func main() {
	character := Character{health: 100}
	character.damage(50)
	fmt.Printf("Character have %d health points\n", character.health)
}

# Defer

package main

import "fmt"

func main() {
	defer fmt.Println("world")

	fmt.Println("hello")
}

$> go run main.go                                                                                                                                                                                                                                                                                                                                                                                                                                                                      ─╯
hello
world

# Goroutines

package main

import (
	"fmt"
	"time"
)

func longRunningFunction(id int) {
	fmt.Printf("%d started\n", id)
	time.Sleep(1 * time.Second)
	fmt.Printf("%d finished!\n", id)
}

func main() {
	for i := 1; i < 10; i++ {
		longRunningFunction(i)
	}
}

# Goroutines

package main

import (
	"fmt"
	"time"
)

func longRunningFunction(id int) {
	fmt.Printf("%d started\n", id)
	time.Sleep(1 * time.Second)
	fmt.Printf("%d finished!\n", id)
}

func main() {
	for i := 1; i < 10; i++ {
		go longRunningFunction(i)
	}
	time.Sleep(2 * time.Second)
}

# Goroutines

package main

import (
	"math/rand"
	"time"
)

type result struct {
	id     int
	number int
}

func longRunningFunction(id int) result {
	time.Sleep(1 * time.Second)
	return result{id: id, number: rand.Int()}
}

func main() {
	for i := 1; i < 10; i++ {
		go longRunningFunction(i)
	}
	time.Sleep(2 * time.Second)
}

# Goroutines

package main

import (
	"math/rand"
	"time"
)

type result struct {
	id     int
	number int
}

func longRunningFunction(id int, channel chan result) result {
	time.Sleep(1 * time.Second)
	return result{id: id, number: rand.Int()}
}

func main() {
	resultChannel := make(chan result)
	for i := 1; i < 10; i++ {
		go longRunningFunction(i, resultChannel)
	}
	time.Sleep(2 * time.Second)
}

# Goroutines

package main

import (
	"fmt"
	"math/rand"
	"time"
)

type result struct {
	id     int
	number int
}

func longRunningFunction(id int, channel chan result) {
	time.Sleep(1 * time.Second)
	channel <- result{id: id, number: rand.Int()}
}

func main() {
	resultChannel := make(chan result)
	for i := 1; i < 10; i++ {
		go longRunningFunction(i, resultChannel)
	}
	for i := 1; i < 10; i++ {
		result := <-resultChannel
		fmt.Printf("%d rolled %d\n", result.id, result.number)
	}
}

# Goroutines

# Goroutines