可以用 stringer 自动生成，举个例子
安装 stringer
```shell
go get -u -a
golang.org/x/tools/cmd/stringer```
**permission.go**
```golang
package core
import (
"sort"
"strings"
)
//go:generate stringer --type Permission
type Permission int
const (
A Permission = iota
B
C
D
E
F
)
func PermissionFromName(p string) (Permission, bool) {
idx := strings.Index(_Permission_name, p)
if idx < 0 {
return 0, false
}
pos := sort.Search(len(_Permission_index), func(i int) bool {
return _Permission_index[i] >= uint8(idx)
})
return Permission(pos), true
}
```
执行 go generate
```shell
go generate ./...
```
生成 **permission_string.go** 文件
```golang
// Code generated by "stringer --type Permission"; DO NOT EDIT.
package core
import "strconv"
func _() {
// An "invalid array index" compiler error signifies that the constant values have changed.
// Re-run the stringer command to generate them again.
var x [1]struct{}
_ = x[A-0]
_ = x[B-1]
_ = x[C-2]
_ = x[D-3]
_ = x[E-4]
_ = x[F-5]
}
const _Permission_name = "ABCDEF"
var _Permission_index = [...]uint8{0, 1, 2, 3, 4, 5, 6}
func (i Permission) String() string {
if i < 0 || i >= Permission(len(_Permission_index)-1) {
return "Permission(" + strconv.FormatInt(int64(i), 10) + ")"
}
return _Permission_name[_Permission_index[i]:_Permission_index[i+1]]
}
```
最后，可以使用 Permission.String() 方法将 enum 转成 string，也可以用 PermissionFromName() 转回来。enum 有变动的时候，重新执行一下 go generate 重新生成代码即可。