Golang フレームワークのベスト プラクティスと設計パターン

// 创建一个形状工厂
package factory

import "fmt"

type Shape interface {
    Draw() string
}

type Circle struct{}

func (c *Circle) Draw() string {
    return "Circle"
}

type Square struct{}

func (s *Square) Draw() string {
    return "Square"
}

// 创建一个形状工厂
func Factory(shapeType string) (Shape, error) {
    switch shapeType {
    case "CIRCLE":
        return &Circle{}, nil
    case "SQUARE":
        return &Square{}, nil
    default:
        return nil, fmt.Errorf("invalid shape type %s", shapeType)
    }
}

// 创建一个主题
package observer

import "fmt"

type Subject interface {
    RegisterObserver(observer Observer)
    RemoveObserver(observer Observer)
    NotifyObservers()
}

// 创建一个具体的主题
type ConcreteSubject struct {
    observers []Observer
    state     string
}

// 创建一个具体的观察者
type ConcreteObserver struct {
    name string
}

// 实现 Subject 接口
func (c *ConcreteSubject) RegisterObserver(observer Observer) {
    c.observers = append(c.observers, observer)
}

func (c *ConcreteSubject) RemoveObserver(observer Observer) {
    for i, o := range c.observers {
        if o == observer {
            c.observers = append(c.observers[:i], c.observers[i+1:]...)
            break
        }
    }
}

func (c *ConcreteSubject) NotifyObservers() {
    for _, observer := range c.observers {
        observer.Update(c.state)
    }
}

// 实现 Observer 接口
func (c *ConcreteObserver) Update(state string) {
    fmt.Printf("Observer %s received notification: %s\n", c.name, state)
}