英文:
Golang: cast interface back to its original type
问题
我无法真正找到这个问题的答案，尽管我查阅了Go的文档和示例。是否可能将接口转换回其原始类型，动态地进行转换？我知道可以像这样做：
var myint int = 5
var myinterface interface{}
myinterface = myint
recovered, _ := myinterface.(int)
fmt.Println(recovered)
但是在这里我知道类型。我想要有一个未知类型（接口）的映射，并通过使用反射将它们转换回来，像这样：
// put/pop writes/read to/from a map[string]interface{}
var myint int = 5
put("key", myint)
pop("key", &myint) // 这也适用于对象或任何其他类型
这样就可以在一个单独的映射中存储任何东西。当调用pop()时，类型将由用户传入（第二个参数是一个接口）。是否可能使用反射来实现这一点？
英文:
I couldn't really find an answer to this, even though I looked up the Go documentation and examples. Is it possible to cast an interface back to its original type, dynamically? I know I can do something like this:
var myint int = 5
var myinterface interface{}
myinterface = myint
recovered, _ := myinterface.(int)
fmt.Println(recovered)
But here I know the type. I would like to have a map of unknown types (interfaces) and cast them back by using reflection, like this:
// put/pop writes/read to/from a map[string]interface{}
var myint int = 5
put("key" myint)
pop("key", &myint) // this should also work for objects or any other type
Like this it would by possible to store anything within a single map. The type will be handed in by the user when calling pop() (second argument is an interface). Is it possible to achive this using reflection?
答案1
得分: 12
你可以在编译时不知道接口的具体类型的情况下断言类型，但你可以通过反射从接口中设置一个值。以下是一个没有错误检查的示例，当任何参数不匹配时会引发 panic：
var m = map[string]interface{}{}
func put(k string, v interface{}) {
m[k] = v
}
func pop(k string, o interface{}) {
reflect.ValueOf(o).Elem().Set(reflect.ValueOf(m[k]))
}
链接：https://play.golang.org/p/ORcKhtU_3O
英文:
You can't assert a type from an interface without knowing what that type is at compile time, but you can set a value from an interface via reflection. Here's an example without any error checks, which panics when any parameters don't match:
var m = map[string]interface{}{}
func put(k string, v interface{}) {
m[k] = v
}
func pop(k string, o interface{}) {
reflect.ValueOf(o).Elem().Set(reflect.ValueOf(m[k]))
}
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