Golang function pointer as a part of a struct

Question

I have the following code:

type FWriter struct {
    WriteF func(p []byte) (n int,err error)
}

func (self *FWriter) Write(p []byte) (n int, err error) {
    ret         


        

Answer 1

There's a typo in your code, but wrapping the func into a struct is unnecessary anyway. Instead, you can just define a WriteFunc type that wraps a function, and that you can define a Write method on. Here's a full example.

package main

import (
    "fmt"
    "io"
    "strings"
)

type WriteFunc func(p []byte) (n int, err error)

func (wf WriteFunc) Write(p []byte) (n int, err error) {
    return wf(p)
}

func myWrite(p []byte) (n int, err error) {
    fmt.Print("%v", p)
    return len(p), nil
}

func main() {
    io.Copy(WriteFunc(myWrite), strings.NewReader("Hello world"))
}