从接口去获取指向结构体的指针？

Given an interface, how do I obtain a pointer to the underlying value?

My naive attempt was to use a type assertion like this:

var mytypeptr *MyType = myinterface.(*MyType)

But I get:

interface conversion: MyInterface is MyType, not *MyType

You could start with, using reflect.Indirect():

val := reflect.ValueOf(myinterface)
if val.Kind() == reflect.Ptr {
    val = reflect.Indirect(val)
}