Go from introduction to actual combat - execute only once (note)

The singleton pattern

var (
	once sync.Once
	obj  *SingletonObj
)

type SingletonObj struct {
    
}

func GetSingletonOb() *SingletonObj {
    
	once.Do(func() {
    
		fmt.Println("Create Singleton obj")
		obj = &SingletonObj{
    }
	})
	return obj
}