我的 Go reflect 筆記

package main

import (

"fmt"

"reflect"

)

type S1 struct {

Name string

Age int

}

type S2 struct {

Name string

Info string

}

type S3 struct {

U string

V string

}

type S4 struct {

K string

V string

}

func main() {

s1 := S1{

Name: "s1: oooo",

Age: 10,

}

s2 := S2{

Name: "s2: test",

Info: "s2: qqq",

}

s3 := S3{

U: "s3: 1",

V: "s3: A",

}

fmt.Println("before change: ")

fmt.Println(s1)

testReflect(&s1)

fmt.Println("after change: ")

fmt.Println(s1)

fmt.Println("======")

fmt.Println("before change: ")

fmt.Println(s2)

testReflect(&s2)

fmt.Println("after change: ")

fmt.Println(s2)

fmt.Println("======")

fmt.Println("before change: ")

fmt.Println(s3)

rType := reflect.TypeOf(s3)

rValue := reflect.ValueOf(&s3)

for i := 0; i < rType.NumField(); i++ {

rValue.Elem().Field(i).SetString(fmt.Sprintf("s3: %d", i))

}

fmt.Println("after change: ")

fmt.Println(s3)

fmt.Println("======")

s4 := testReflect(S4{

K: "s4: a000",

V: "s4: p777",

})

fmt.Println(s4)

s4Ptr := testReflect(&S4{

K: "q111",

V: "q222",

})

fmt.Println(s4Ptr)

}

func testReflect(i interface{}) interface{} {

rValueOf := reflect.ValueOf(i)

ret := i

switch i.(type) {

case *S1:

ret := rValueOf.Interface().(*S1)

ret.Name = "*s1: rrrr"

ret.Age = 19

case *S2:

ret := rValueOf.Interface().(*S2)

ret.Name = "*s2: 222"

ret.Info = "*s2: good"

case S3:

s3 := reflect.New(reflect.TypeOf(i))

newS3 := s3.Elem().Interface().(S3)

newS3.U = "s3: test"

newS3.V = "s3: 1234"

return newS3

case S4:

rValue := reflect.ValueOf(&i)

s4 := rValue.Elem().Interface().(S4)

s4.K = "s4: 0"

s4.V = "s4: 1"

return s4

case *S4:

rValue := reflect.ValueOf(i)

for i := 0; i < rValue.Elem().NumField(); i++ {

rValue.Elem().Field(i).SetString(fmt.Sprintf("*s4: %d", i))

}

return rValue

}

return ret

}