[] byte或文件中的io.WriteSeeker和io.ReadSeeker

Question

I have a method called "DoSomething". DoSomething will take binary source data perform an operation on it, and write out binary data. DoSomething needs to be generic enough to handle either a []byte array or a file handle for both the source and destination. To accomplish this, I have attempted to declare the method like this:

func DoSomething(source *io.ReadSeeker, destination *io.WriteSeeker)

I have implemented the ReadSeeker and WriteSeeker for working with buffers, using my own custom, required methods (if there is a way to automatically accomplish this, I'd love to hear about it as well). Unfortunately, I can't seem to figure out how to create either an io.ReadSeeker or io.WriteSeeker from a file handle. I'm fairly sure there must be some pre-cooked way of handling this without having to manually implement them. Is this possible?

Answer 1

A file already implements both of those. You can do something like this:

package main

import (
   "fmt"
   "io"
   "os"
)

func main() {
   f, err := os.Open("test.txt")
   if err != nil {
     fmt.Println(err)
   }
   defer f.Close()
   f2, err := os.Create("test2.txt")
   if err != nil {
      fmt.Println(err)
   }
   defer f2.Close()
   DoSomething(f, f2) 
}

func DoSomething(source io.ReadSeeker, destination io.WriteSeeker) {
   io.Copy(destination, source)
}

Also, you don't need to pass pointers to interfaces, which makes it easier to deal with them.