英文:
Golang interface conversion error: missing method
问题
看一下这段代码：
package main
type Interface interface {
Interface()
}
type Struct struct {
Interface
}
func main() {
var i interface{} = Struct{}
_ = i.(Interface)
}
结构体 Struct 嵌入了实现接口 Interface 的成员。当我编译这段代码时，我得到了一个错误：
panic: interface conversion: main.Struct is not main.Interface: missing method Interface
这看起来很奇怪，因为结构体 Struct 应该从嵌入的接口 Interface 继承了方法 Interface。
我想知道为什么会出现这个错误？这是 golang 的设计如此，还是只是 golang 编译器的一个 bug？
英文:
Look at this snippet:
package main
type Interface interface {
Interface()
}
type Struct struct {
Interface
}
func main() {
var i interface{} = Struct{}
_ = i.(Interface)
}
struct Struct has a embeded member implements interface Interface. When I compile this snippet, I get an error:
panic: interface conversion: main.Struct is not main.Interface: missing method Interface
This seems weird because struct Struct should inherit method Interface from the embeded interface Interface.
I want to know why this error happens? Is it designed as this in golang or is it just a bug of golang compiler?
答案1
得分: 3
你不能同时拥有一个字段和一个同名的方法，当你嵌入一个名为X的东西并提供一个方法X()时，就会发生这种情况。
按照现有的写法，Struct{}.Interface是一个字段，而不是一个方法。没有Struct.Interface()，只有Struct.Interface.Interface()。
重新命名你的接口。例如，这样可以正常工作：
package main
type Foo interface {
Interface()
}
type Struct struct {
Foo
}
func main() {
var i interface{} = Struct{}
_ = i.(Foo)
}
英文:
You can't have both a field and a method with the same name, which is what happens when you embed something named X that provides a method X().
As written. Struct{}.Interface is a field, not a method. There is no Struct.Interface(), only Struct.Interface.Interface().
Rename your interface. For example, this works fine:
package main
type Foo interface {
Interface()
}
type Struct struct {
Foo
}
func main() {
var i interface{} = Struct{}
_ = i.(Foo)
}
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