The Way to Go/

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A Practical Example of Interfaces

A Practical Example of Interfaces

This lesson provides an explanation of the use of interfaces for writing to the console by using a buffer.

We'll cover the following...

The following program is a nice illustration of the concept of interfaces in io:

Go (1.6.2)
package main
import (
"bufio"
"fmt"
"os"
)
func main() {
  // unbuffered: os.Stdout implements io.Writer
  fmt.Fprintf(os.Stdout, "%s\n", "hello world! - unbuffered")
  // buffered:
  buf := bufio.NewWriter(os.Stdout)
  // and now so does buf:
  fmt.Fprintf(buf, "%s\n", "hello world! - buffered")
  buf.Flush()
}

Here is the actual signature of fmt.Fprintf():

func Fprintf(w io.Writer, format string, a ...interface {}) (n int, err error)

It doesn’t write to a file, it writes to a variable of type io.Writer, that is: ...