mirror of
https://github.com/golang/go
synced 2024-11-13 16:50:23 -07:00
5b7562dd6f
cgo[1-4].go, go1.go couldn't be tested now (cgo[1-4].go can only be tested when cgo is enabled, go1.go contain a list of filenames in the current directory) R=golang-dev, alex.brainman, rsc CC=golang-dev https://golang.org/cl/6218048
135 lines
2.6 KiB
Go
135 lines
2.6 KiB
Go
// cmpout
|
|
|
|
// Copyright 2012 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
// This file contains the code snippets included in "The Laws of Reflection."
|
|
|
|
package main
|
|
|
|
import (
|
|
"fmt"
|
|
"reflect"
|
|
)
|
|
|
|
func main() {
|
|
var x float64 = 3.4
|
|
fmt.Println("type:", reflect.TypeOf(x))
|
|
// STOP OMIT
|
|
// TODO(proppy): test output OMIT
|
|
}
|
|
|
|
// STOP main OMIT
|
|
|
|
func f1() {
|
|
// START f1 OMIT
|
|
var x float64 = 3.4
|
|
v := reflect.ValueOf(x)
|
|
fmt.Println("type:", v.Type())
|
|
fmt.Println("kind is float64:", v.Kind() == reflect.Float64)
|
|
fmt.Println("value:", v.Float())
|
|
// STOP OMIT
|
|
}
|
|
|
|
func f2() {
|
|
// START f2 OMIT
|
|
var x uint8 = 'x'
|
|
v := reflect.ValueOf(x)
|
|
fmt.Println("type:", v.Type()) // uint8.
|
|
fmt.Println("kind is uint8: ", v.Kind() == reflect.Uint8) // true.
|
|
x = uint8(v.Uint()) // v.Uint returns a uint64.
|
|
// STOP OMIT
|
|
}
|
|
|
|
func f3() {
|
|
// START f3 OMIT
|
|
type MyInt int
|
|
var x MyInt = 7
|
|
v := reflect.ValueOf(x)
|
|
// STOP OMIT
|
|
// START f3b OMIT
|
|
y := v.Interface().(float64) // y will have type float64.
|
|
fmt.Println(y)
|
|
// STOP OMIT
|
|
// START f3c OMIT
|
|
fmt.Println(v.Interface())
|
|
// STOP OMIT
|
|
// START f3d OMIT
|
|
fmt.Printf("value is %7.1e\n", v.Interface())
|
|
// STOP OMIT
|
|
}
|
|
|
|
func f4() {
|
|
// START f4 OMIT
|
|
var x float64 = 3.4
|
|
v := reflect.ValueOf(x)
|
|
v.SetFloat(7.1) // Error: will panic.
|
|
// STOP OMIT
|
|
}
|
|
|
|
func f5() {
|
|
// START f5 OMIT
|
|
var x float64 = 3.4
|
|
v := reflect.ValueOf(x)
|
|
fmt.Println("settability of v:", v.CanSet())
|
|
// STOP OMIT
|
|
}
|
|
|
|
func f6() {
|
|
// START f6 OMIT
|
|
var x float64 = 3.4
|
|
v := reflect.ValueOf(x)
|
|
// STOP OMIT
|
|
// START f6b OMIT
|
|
v.SetFloat(7.1)
|
|
// STOP OMIT
|
|
}
|
|
|
|
func f7() {
|
|
// START f7 OMIT
|
|
var x float64 = 3.4
|
|
p := reflect.ValueOf(&x) // Note: take the address of x.
|
|
fmt.Println("type of p:", p.Type())
|
|
fmt.Println("settability of p:", p.CanSet())
|
|
// STOP OMIT
|
|
// START f7b OMIT
|
|
v := p.Elem()
|
|
fmt.Println("settability of v:", v.CanSet())
|
|
// STOP OMIT
|
|
// START f7c OMIT
|
|
v.SetFloat(7.1)
|
|
fmt.Println(v.Interface())
|
|
fmt.Println(x)
|
|
// STOP OMIT
|
|
}
|
|
|
|
func f8() {
|
|
// START f8 OMIT
|
|
type T struct {
|
|
A int
|
|
B string
|
|
}
|
|
t := T{23, "skidoo"}
|
|
s := reflect.ValueOf(&t).Elem()
|
|
typeOfT := s.Type()
|
|
for i := 0; i < s.NumField(); i++ {
|
|
f := s.Field(i)
|
|
fmt.Printf("%d: %s %s = %v\n", i,
|
|
typeOfT.Field(i).Name, f.Type(), f.Interface())
|
|
}
|
|
// STOP OMIT
|
|
// START f8b OMIT
|
|
s.Field(0).SetInt(77)
|
|
s.Field(1).SetString("Sunset Strip")
|
|
fmt.Println("t is now", t)
|
|
// STOP OMIT
|
|
}
|
|
|
|
func f9() {
|
|
// START f9 OMIT
|
|
var x float64 = 3.4
|
|
fmt.Println("value:", reflect.ValueOf(x))
|
|
// STOP OMIT
|
|
}
|