单例模式

使用单例的目的是为了保证在整个系统中存在唯一的实例

package mainimport (        "fmt"        "sync")type IntAndString struct {        num int32        str string}var m *IntAndStringvar once sync.Oncefunc GetInstance() *IntAndString {        once.Do(func() {        m = &IntAndString{num:1, str:"fdjkslf"}        })        return m}func (m *IntAndString) String() {        fmt.Printf("int %v, string %v\n", m.num, m.str)}func main() {        tmp := GetInstance()        tmp.String()        tmp.str = "hello"        tmp1 :=  GetInstance()        tmp1.String()        tmp.String()}

运行结果

int 1, string fdjkslfint 1, string helloint 1, string hello