Golang 特殊类型

package main

type User struct {
   Id     int
   Name   string
   Amount float64
}

func main() {
   //声明struct
   var u User
   u.Id = 1

}

package main

import "fmt"

func main() {
   var fn func()
   fn = func() {
      fmt.Println("anonymous func")
   }
   fn()
   fn = test
   fn()
}
func test() {
   fmt.Println("test")
}

package main

import "fmt"

func main() {
   var fn func() (interface{}, error)
   fn=test1
   name,err := fn()
   fmt.Println(name,err)
}
func test1() (interface{}, error){
   fmt.Println("test1")
   return "test1 func", nil
}

package main

import "fmt"

func main() {
   var fn func(interface{}) error
   fn = test3
   err := fn("test3")
   fmt.Println(err)
}
func test3(name interface{}) error {
   fmt.Println(name)
   return nil
}

package main

import (
   "fmt"
   "reflect"
)

type User struct {
   Id     int
   Name   string
   Amount float64
}
type HandlerTypeVoid func()
type HandlerTypeString func() string
type HandlerTypeError func(interface{}) error

func main() {
   var i interface{}
   i = "string"
   fmt.Println(i)
   i = 1
   fmt.Println(i)
   i = User{Id: 2}
   //i.(User).Id = 15  //运行此处会报错，在函数中修改interface表示的结构体的成员变量的值，编译时遇到这个编译错误，cannot assign to i.(User).Id
   fmt.Println(i.(User).Id)
   i = test
   r := i.(func(v interface{}) error)("test_1")
   fmt.Println(r)
   //不同过反射调用函数
   var err error
   switch i.(type) { //通过使用.(type)方法可以利用switch来判断接口存储的类型。
   case func(string):
   case func(string, string):
      //...
   case func(interface{}) error:
      if f, ok := i.(func(v interface{}) error); ok {
         err = HandlerTypeError(f)("test_2")
      }
      break
   default:
      break
   }
   fmt.Println(err)
   //通过反射
   v := reflect.ValueOf(i)
   rargs := make([]reflect.Value, 1)
   rargs[0] = reflect.ValueOf("test_3")
   res := v.Call(rargs)
   fmt.Println(res)

}
func test(name interface{}) error {
   fmt.Println(name)
   return nil
}