Design patterns are widely used in the Go framework to improve code flexibility and maintainability. Specific design patterns include: Singleton pattern: ensures that a class has only one instance; Observer pattern: allows objects to subscribe to and respond to events; Factory method pattern: provides an interface to create objects, and the specific creation of the class is determined by the subclass.
In-depth understanding of design patterns in the Go framework
Design patterns are commonly used models for reproducible problem solving in software engineering , widely used in the Go framework. By understanding these patterns, developers can write more flexible, maintainable, and scalable code.
1. Singleton pattern
Ensures that only one instance of a class is created.
import ( "sync" "fmt" ) type Singleton struct { sync.Mutex isInitialized bool instance *Singleton } func GetInstance() *Singleton { s := &Singleton{} s.Lock() defer s.Unlock() if !s.isInitialized { s.instance = s s.isInitialized = true } return s.instance } func main() { instance1 := GetInstance() instance2 := GetInstance() fmt.Println(instance1 == instance2) // true }
2. Observer pattern
Allows objects to subscribe to and respond to events.
import ( "fmt" "sync" ) type Subject interface { Attach(observer Observer) Detach(observer Observer) Notify() } type Observer interface { Update() } type ConcreteSubject struct { sync.Mutex observers []Observer state string } func (s *ConcreteSubject) Attach(observer Observer) { s.Lock() defer s.Unlock() s.observers = append(s.observers, observer) } func (s *ConcreteSubject) Detach(observer Observer) { s.Lock() defer s.Unlock() for i, o := range s.observers { if o == observer { s.observers = append(s.observers[:i], s.observers[i+1:]...) return } } } func (s *ConcreteSubject) Notify() { s.Lock() defer s.Unlock() for _, observer := range s.observers { observer.Update() } } func (s *ConcreteSubject) SetState(state string) { s.Lock() defer s.Unlock() s.state = state s.Notify() } type ConcreteObserver struct { id int sub *ConcreteSubject } func (o *ConcreteObserver) Update() { fmt.Printf("ConcreteObserver %d notified, subject state: %s\n", o.id, o.sub.state) } func main() { subject := &ConcreteSubject{} observer1 := &ConcreteObserver{id: 1, sub: subject} observer2 := &ConcreteObserver{id: 2, sub: subject} subject.Attach(observer1) subject.Attach(observer2) subject.SetState("New state") }
3. Factory method pattern
Provides an interface to create objects, but the specific creation class is determined by the subclass.
import "fmt" type Product interface { GetName() string } type ProductA struct{} func (p *ProductA) GetName() string { return "ProductA" } type ProductB struct{} func (p *ProductB) GetName() string { return "ProductB" } type Factory interface { CreateProduct() Product } type FactoryA struct{} func (f *FactoryA) CreateProduct() Product { return &ProductA{} } type FactoryB struct{} func (f *FactoryB) CreateProduct() Product { return &ProductB{} } func main() { factoryA := &FactoryA{} productA := factoryA.CreateProduct() fmt.Println(productA.GetName()) // "ProductA" factoryB := &FactoryB{} productB := factoryB.CreateProduct() fmt.Println(productB.GetName()) // "ProductB" }
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