lesson 6

lesson_6/animals/go.mod

@@ -0,0 +1,5 @@
+module animals
+
+go 1.22.2
+
+require golang.org/x/text v0.16.0

lesson_6/animals/go.sum

@@ -0,0 +1,2 @@
+golang.org/x/text v0.16.0 h1:a94ExnEXNtEwYLGJSIUxnWoxoRz/ZcCsV63ROupILh4=
+golang.org/x/text v0.16.0/go.mod h1:GhwF1Be+LQoKShO3cGOHzqOgRrGaYc9AvblQOmPVHnI=

lesson_6/animals/main.go

@@ -0,0 +1,79 @@
+package main
+
+import (
+ "fmt"
+ "os"
+
+ "animals/pets"
+)
+
+func main() {
+ myCat := pets.Cat{
+ Animal: pets.Animal{Name: "mr. buttons"},
+ Age: 5,
+ IsAsleep: true,
+ }
+ myDog := pets.Dog{
+ Animal: pets.Animal{Name: "spot"},
+ Age: 6,
+ Weight: 30,
+ }
+
+ var feedToCat uint8 = 3
+ var feedToDog uint8 = 10
+
+ catFed, err := feed(&myCat, feedToCat)
+ if err != nil {
+ fmt.Fprintf(os.Stderr, "Error feeding cat: %v\n", err)
+ } else {
+ fmt.Println("Cat ate:", catFed)
+ }
+
+ fmt.Print("\n\n\t =====\n\n\n")
+
+ dogFed, err := feed(&myDog, feedToDog)
+ if err != nil {
+ fmt.Fprintf(os.Stderr, "Error feeding dog: %v\n", err)
+ } else {
+ fmt.Println("Dog ate:", dogFed)
+ }
+
+ fmt.Print("\n\n\t =====\n\n\n")
+
+ displayInfo(myCat)
+ displayInfo(myDog)
+ displayInfo(42)
+}
+
+func feed(animal pets.EaterWalker, amount uint8) (uint8, error) {
+ switch v := animal.(type) {
+ case *pets.Cat:
+ fmt.Println(v.GetName(), "is a cat aged", v.Age)
+ case *pets.Dog:
+ fmt.Println(v.GetName(), "is a dog aged", v.Age)
+ default:
+ fmt.Println("Unknown animal type")
+ }
+
+ fmt.Println("First, let's walk!")
+ fmt.Println(animal.Walk())
+
+ fmt.Println("Now, let's feed our", animal.GetName())
+
+ return animal.Eat(amount)
+}
+
+func displayInfo(i interface{}) {
+ switch v := i.(type) {
+ case string:
+ fmt.Println("This is a string:", v)
+ case int:
+ fmt.Println("This is an int:", v)
+ case pets.Cat:
+ fmt.Println("This is a Cat named:", v.Name, "and it is", v.Age, "years old")
+ case pets.Dog:
+ fmt.Println("This is a Dog named:", v.Name, "and weight:", v.Weight)
+ default:
+ fmt.Println("Unknown type")
+ }
+}

lesson_6/animals/pets/cat.go

@@ -0,0 +1,22 @@
+package pets
+
+type Cat struct {
+ Animal
+ Age uint8
+ IsAsleep bool
+}
+
+func (c *Cat) Eat(amount uint8) (uint8, error) {
+ if c.IsAsleep {
+ return 0, &ActionError{Name: c.GetName(), Reason: "it is asleep"}
+ }
+
+ if amount > 5 {
+ return 0, newError("Cat can't eat that much", nil)
+ }
+ return amount, nil
+}
+
+func (c *Cat) Walk() string {
+ return "Cat is walking!"
+}

lesson_6/animals/pets/dog.go

@@ -0,0 +1,23 @@
+package pets
+
+type Dog struct {
+ Animal
+ Age uint8
+ Weight uint8
+ IsAsleep bool
+}
+
+func (d *Dog) Eat(amount uint8) (uint8, error) {
+ if d.IsAsleep {
+ return 0, &ActionError{Name: d.Name, Reason: "it is asleep"}
+ }
+
+ if amount > 15 {
+ return 0, newError("Dog can't eat that much", nil)
+ }
+ return amount, nil
+}
+
+func (d *Dog) Walk() string {
+ return "Dog is walking!"
+}

lesson_6/animals/pets/pets.go

@@ -0,0 +1,51 @@
+package pets
+
+import (
+ "fmt"
+
+ "golang.org/x/text/cases"
+ "golang.org/x/text/language"
+)
+
+type Eater interface {
+ Eat(amount uint8) (uint8, error)
+}
+
+type Walker interface {
+ Walk() string
+}
+
+type Named interface {
+ GetName() string
+}
+
+type EaterWalker interface {
+ Eater
+ Walker
+ Named
+}
+
+type Animal struct {
+ Name string
+}
+
+type ActionError struct {
+ Name string
+ Reason string
+}
+
+func (e *ActionError) Error() string {
+ return fmt.Sprintf("%s cannot perform the action: %s", e.Name, e.Reason)
+}
+
+func (a *Animal) GetName() string {
+ caser := cases.Title(language.English)
+ return caser.String(a.Name)
+}
+
+func newError(msg string, err error) error {
+ if err != nil {
+ return fmt.Errorf("%s: %w", msg, err)
+ }
+ return fmt.Errorf(msg)
+}

lesson_6/shuffler/go.mod

@@ -0,0 +1,3 @@
+module shuffler
+
+go 1.22.2

lesson_6/shuffler/main.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+ "fmt"
+ "math/rand"
+ "reflect"
+)
+
+type Question struct {
+ Country string `json:"country"`
+ Capital string `json:"capital"`
+}
+
+func Shuffle(slice interface{}) {
+ rv := reflect.ValueOf(slice)
+
+ if rv.Kind() != reflect.Slice {
+ fmt.Println("Shuffle: provided interface is not a slice type")
+ return
+ }
+
+ length := rv.Len()
+ swap := reflect.Swapper(slice)
+
+ rand.Shuffle(length, func(i, j int) {
+ swap(i, j)
+ })
+}
+
+func main() {
+ questions := []Question{
+ {Country: "France", Capital: "Paris"},
+ {Country: "Germany", Capital: "Berlin"},
+ {Country: "Italy", Capital: "Rome"},
+ }
+
+ fmt.Println("Before shuffle:", questions)
+ Shuffle(questions)
+ fmt.Println("After shuffle:", questions)
+
+ numbers := []int{1, 2, 3, 4, 5}
+
+ fmt.Println("Before shuffle:", numbers)
+ Shuffle(numbers)
+ fmt.Println("After shuffle:", numbers)
+
+ Shuffle(42)
+}