英文:
Improve reflection between extended implementors
问题
我有一个Result接口，表示结果的最小状态。现在有不同的结构体实现了Result接口，但也添加了自己的方法。其中之一是SpecialResult，它实现了基本的Value()方法，还有一个特殊的Special()方法。
你可以在下面的代码片段中看到这个情况：
package main
import (
"fmt"
"reflect"
)
type Result interface {
Value() string
}
type SpecialResult struct {
value string
}
func (r *SpecialResult) Value() string {
return r.value
}
func (r *SpecialResult) Special() string {
return "look I am special!!"
}
func main() {
sr := &SpecialResult{
value: "1234",
}
doSomething(sr)
}
func doSomething(r Result) {
switch reflect.TypeOf(r).String() {
case "*main.SpecialResult":
fmt.Printf("%s, %s\n", r.Value(), r.(*SpecialResult).Special())
break
default:
fmt.Printf("%s\n", r.Value())
}
}
当你阅读代码的最后几行时，你可能会和我有同样的感觉：这看起来非常奇怪。
有没有更好的方法来实现这个设置？
Bodo
英文:
I have a Result interface which represents the minimum state of a result. Now there are different structs which implement the Result interface but also add own methods. One of them is SpecialResult which implemented the basic Value() method but also a special Special() method.
You can see this in the following snippet:
package main
import (
"fmt"
"reflect"
)
type Result interface {
Value() string
}
type SpecialResult struct {
value string
}
func (r *SpecialResult) Value() string {
return r.value
}
func (r *SpecialResult) Special() string {
return "look I am special!!"
}
func main() {
sr := &SpecialResult{
value: "1234",
}
doSomething(sr)
}
func doSomething(r Result) {
switch reflect.TypeOf(r).String() {
case "*main.SpecialResult":
fmt.Printf("%s, %s\n", r.Value(), r.(*SpecialResult).Special())
break
default:
fmt.Printf("%s\n", r.Value())
}
}
When you read the last lines of code you might feel the same as I do: This looks very weird.
Is there a better way to achieve the shown setup?
Bodo
答案1
得分: 4
使用类型断言
package main
import (
"fmt"
)
type Result interface {
Value() string
}
type SpecialResult struct {
value string
}
func (r *SpecialResult) Value() string {
return r.value
}
func (r *SpecialResult) Special() string {
return "look I am special!!"
}
func main() {
sr := &SpecialResult{
value: "1234",
}
doSomething(sr)
}
func doSomething(r Result) {
if special, ok := r.(*SpecialResult); ok {
fmt.Printf("%s, %s\n", special.Value(), special.Special())
} else {
fmt.Printf("%s\n", r.Value())
}
}
英文:
Use Type Assertions
package main
import (
"fmt"
)
type Result interface {
Value() string
}
type SpecialResult struct {
value string
}
func (r *SpecialResult) Value() string {
return r.value
}
func (r *SpecialResult) Special() string {
return "look I am special!!"
}
func main() {
sr := &SpecialResult{
value: "1234",
}
doSomething(sr)
}
func doSomething(r Result) {
if special, ok := r.(*SpecialResult); ok {
fmt.Printf("%s, %s\n", special.Value(), special.Special())
} else {
fmt.Printf("%s\n", r.Value())
}
}
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