问题描述
我有以下代码:
package main
type MyInterface interface {
Test()
}
type MyType struct {
}
func (m MyType) Test(){}
func AcceptInterface(i *MyInterface){
}
func main() {
object := &MyType{}
AcceptInterface(object)
}
我期望它能起作用，因为MyType实现了MyInterface，但是我得到了:
I was expecting this to work, because MyType implements MyInterface, but I get:
我尝试做类型断言:object.(MyInterface)，但这也不起作用.
I tried doing type assertion: object.(MyInterface), but that doesn't work either.
我该怎么做?
推荐答案
如错误所示，
这意味着它期望一个 interface 值，而不是一个指针.
This means that it is expecting an interface value, not a pointer.
如果将指针更改为代码中的值(通过删除& 和 * )，程序将无错误运行:
If you change the pointers to values in your code (by removing the & and *), the program will run with no errors:
package main
type MyInterface interface {
Test()
}
type MyType struct {
}
func (m MyType) Test(){}
func AcceptInterface(i MyInterface){
}
func main() {
object := MyType{}
AcceptInterface(object)
}
如果您仍想使用指针作为参数，则Go语言中有两个重要的部分需要注意
If you still want to use a pointer as an argument, there are two important parts of the Go language to note
-
从 Go Spec 中了解 exacly 是什么适合实例的变量:
From the Go Spec on what exacly is a variable that fits an instance:
从转到Spec 中，了解哪些指针已自动取消引用:
From the Go Spec on what pointers being automatically dereferenced:
这两个要点很重要，因为将它们结合起来可以解释指向变量的指针仍然可以适合实例.这是因为Go编译器自动取消了指针的方法集的引用(并且自从所引用的变量可以适合实例，指针也可以)！
Those two points are important, because when combined they explain that pointers to variables can still fit instances. This is because the pointer's method set is automatically dereferenced by the Go compiler (and since the variable it is referencing can fit an instance, the pointer can, too)!
实际上，这意味着要查看指针是否适合实例，必须将实例声明为 value ，并将指针声明为 pointer .
In action, this means that in order to see if a pointer fits an instance, you have to declare the instance as a value and the pointer as a pointer.
如果运行此代码:
package main
type MyInterface interface {
Test()
}
type MyType struct {
}
func (m MyType) Test() {}
func AcceptInterface(i MyInterface) {
}
func main() {
object := &MyType{}
AcceptInterface(object)
}
您将看到没有错误！请注意，在 object 声明中 是& ，但是没有 * 在 i 声明中?
you will see that there are no errors! Notice how there is an & in the object declaration, but no * in the i declaration?
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