How to force compliler to control value/pointer-to-value func arguments?

Question

Hi! Dealing with go's funcs I discovered that can't force the compiler to control whether I pass a value or pointer-to-value argument when using 'generic' interface{} type.

func f(o interface{}) {
...
}

The most obvious solution is to use the following modification:

func f(o *interface{}) {
...
}

Although this is successfully compiled I didn't find this step right. So, is there any means to state that I want to pass any pointer?

Answer 1

No. At compile time, interface{}, the empty interface, is any type.

all types implement the empty interface: interface{} Interface types

Answer 2

You'd have to use reflection.

import "reflect"

func f(o interface{}) {
  if _, ok := reflect.Typeof(o).(*reflect.PtrType); !ok {
    panic("Not a pointer")
  }
  // ...
}

You could also consider unsafe.Pointer, but the type information would be lost.