func interfaceTest2() {
var s = new(interfacetest.S)
var s2 interfacetest.S
s2.Put(22)
s.Put(100)
fmt.Println("\n------------interface test---------\n")
fmt.Println(g(s))
fmt.Println(g(s2))
fmt.Println(g(&s2))
i := 5
fmt.Println(g(i))
fmt.Printf(" type is %T %T %T ", s, s2, i)
// g type is *interfacetest.S g2 type is *interfacetest.S &{100} 100
// g type is interfacetest.S g2 type is <nil> <nil> -1
// g type is *interfacetest.S g2 type is *interfacetest.S &{22} 22
// g type is int g2 type is <nil> <nil> -1
// type is *interfacetest.S interfacetest.S int
fmt.Printf("\n------------interface test---------\n")
}
func interfaceTest() {
//var s = interfacetest.S(1)
//s2 := interfacetest.S
s := new(interfacetest.S)
s2 := interfacetest.S(*s) // interfacetest.S类型，不能作为interfacetest.InterTest的参数
s.Age = 99
s.Put(88)
s2.Put(199)
s2.Age = 999
fmt.Printf("interfaceTest\n")
interfacetest.InterTest(s)
//接收者是指针不能传递值 正确
//接受者是值能够传递指针 ？
interfacetest.InterTest(&s2) // interfacetest.S does not implement interfacetest.MyI (Get method requires pointer receiver)
fmt.Printf("s type is %T ,s2 type is %T\n", s, s2) //s type is *interfacetest.S ,s2 type is interfacetest.S
var mys interfacetest.S
mys.Age = 88
interfacetest.InterTest(&mys) // interfacetest.S does not implement interfacetest.MyI (Get method requires pointer receiver)
mys.Get()
mys.Put(9)
var mysw *interfacetest.S
//mysw.Age = 90 //panic: runtime error: invalid memory address or nil pointer dereference
fmt.Printf("mys type is %T ,mysw type is %T value %v\n", mys, mysw, mysw) //mys type is interfacetest.S ,mysw type is *interfacetest.S
//mysw.Put(89) //会出错 panic: runtime error: invalid memory address or nil pointer dereference
mysw = s
mysw.Age = 90
mysw.Get()
interfacetest.InterTest(mysw)
var mys2 interfacetest.S2
mys2.Age = 98
interfacetest.InterTest(mys2)
mys2.Get()
fmt.Printf("mys type is %T ,mys2 type is %T value %v\n", mys, mys2, mys2) //mys type is interfacetest.S ,mys2 type is interfacetest.S2
var mys2w *interfacetest.S2
//mys2w.Age = 90 panic: runtime error: invalid memory address or nil pointer dereference
//mys2w.Get() 会出错
mys2w = &mys2
mys2w.Age = 90
interfacetest.InterTest(mys2w)
mys2w.Get()
fmt.Printf("mys2 type is %T ,mys2w type is %T\n", mys2, mys2w) //mys2 type is interfacetest.S2 ,mys2w type is *interfacetest.S2
//t,ok := mys.(interfacetest.MyI) //invalid type assertion: mys.(interfacetest.MyI) (non-interface type interfacetest.S on left)
var myI interfacetest.MyI
//myI.Put(199) 出错
//var myI2 interfacetest.S2
t, ok := myI.(interface{})
// if t, ok := mys.(interfacetest.MyI); ok {
// // 对于某些实现了接口I 的
// // t 是其所拥有的类型
// }
fmt.Printf("myI type is %T ,myI type is ok %v\n", t, ok) //myI type is <nil> ,myI type is ok false
t, ok = myI.(interfacetest.S2)
fmt.Printf("myI type is %T ,myI type is ok %v\n", t, ok) //myI type is interfacetest.S2 ,myI type is ok false
//a,b := s.(interfacetest.MyI)
t, ok = myI.(interfacetest.MyI)
fmt.Printf("myI type is %T ,myI type is ok %v\n", t, ok) //myI type is <nil> ,myI type is ok false
var ddd interface{}
ddd = s
t, ok = ddd.(interfacetest.MyI)
fmt.Printf("%T ddd type is %T ,myI type is ok %v\n", ddd, t, ok) //*interfacetest.S ddd type is *interfacetest.S ,myI type is ok true
ddd = mys
t, ok = ddd.(interfacetest.MyI)
fmt.Printf("%T ddd type is %T ,myI type is ok %v\n", ddd, t, ok) //interfacetest.S ddd type is <nil> ,myI type is ok false
var n *NameAge //在NameAge中的doSomething中用到了成员就会报错 anic: runtime error: invalid memory address or nil pointer dereference
n = &NameAge{"name", 2}
n.doSomething(2)
var n2 NameAge
n2.doSomething(2)
fmt.Printf("\nn2 type is %T , value is %v\n", n2, n2)
fmt.Printf("\nn type is %T , value is %v\n", n, n)
var rtest *interfacetest.AA
rtest.Get()
fmt.Printf("\nrtest type is %T , value is %v\n", rtest, rtest) //rtest type is *interfacetest.AA , value is <nil>
//下面有错误，上面没有错误
// var ftest *interfacetest.S
// ftest.Get()
}