如何将nil接口转换为nil其他接口 [英] How to cast nil interface to nil other interface
问题描述
我有一个经典的Go nil接口问题.
I have a classic Go nil interface issue.
我试图声明一个interface{}
,我将它从nil
error
分配回一个error
接口.该句子令人困惑,因此我有一个方便的示例: https://play.golang.com/p/Qhv7197oIE_z
I'm trying to assert an interface{}
, which I assign from a nil
error
, back to an error
interface. That sentence is confusing so I have a handy-dandy example: https://play.golang.com/p/Qhv7197oIE_z
package main
import (
"fmt"
)
func preferredWay(i interface{}) error {
return i.(error)
}
func workAround(i interface{}) error {
if i == nil {
return nil
}
return i.(error)
}
func main() {
var nilErr error
fmt.Println(workAround(nilErr)) // Prints "<nil>" as expected.
fmt.Println(preferredWay(nilErr)) // Panics.
}
输出:
<nil>
panic: interface conversion: interface is nil, not error
goroutine 1 [running]:
main.preferredWay(...)
/tmp/sandbox415300914/prog.go:8
main.main()
/tmp/sandbox415300914/prog.go:21 +0xa0
因此,换句话说,我正在尝试从nil
interface{}
向下转换为nil
error
接口.如果我知道interface{}
首先被指定为nil
error
,是否有一种优雅的方法?
So in other words, I'm trying to downcast from a nil
interface{}
to a nil
error
interface. Is there an elegant way to do this if I know the interface{}
was assigned as a nil
error
to begin with?
仅供参考,如果这看起来很不正常,那是因为我正在实现一些模拟测试.
FYI, if this seems unusual, it's because I'm implementing some mocking for testing.
推荐答案
这项工作有效吗?
func preferredWay(i interface{}) error {
k, _ := i.(error)
return k
}
这篇关于如何将nil接口转换为nil其他接口的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!