Copying Pointers in Go

Over a year ago I was trying to make a copy of a *url.URL and ended up with this quite nasty way to do so. I even applied this to maskpass, a small package that masks the password of an url.URL to make it log-friendly.

But today, looking for a nice clean way to do so in a PR being sent to Go I realized tmp := *src does the work nicely.

package main

import (
  "fmt"
  "net/url"
)

func main() {
  src, _ := url.Parse("http://user:[email protected]/")
  tmp := *src
  tmp.User = url.UserPassword(tmp.User.Username(), "xxxxx")
  fmt.Printf("%s, %s", src.String(), tmp.String())
}

https://play.golang.org/p/F4vaqN3wC_H

What this shows is that changing values in tmp won’t change the values in src so you have effectively copied the values of the source pointer to a new pointer.

So, if you’re looking for a clean way to copy the value of a pointer in Go, hopefully, this will help you.