接口值的基础指针类型

Question

How do I get the underlying pointer type from an interface?

package main

import (
    "fmt"
)

type Car interface  {
    Drive() string
}
type MyCar struct   {
    name string
}
func (MyCar) Drive (  ) string  {
    return "rum rum"
}


func main() {
    var car Car
    mycar := &MyCar{name:"mycar"}
    car = mycar
    mycarptr, err :=  car.(*MyCar)
    mycarvalue, err2 :=  car.(MyCar)
    fmt.Printf( "as ptr failed: %t, as value failed: %t
", err, err2 )
    fmt.Printf( "as ptr: %+v, as value: %+v", mycarptr, mycarvalue)
}

Answer 1

Your first assertion to *MyCar works fine

Here is a playground example to illustrate

Your second assertion to MyCar will fail since it's not a pointer.