Powerful Command-Line Applications in Go/

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Capturing Input from STDIN

Capturing Input from STDIN

Learn how to get input from STDIN.

We'll cover the following...

Good command-line tools interact well with our users, but they also work well with other tools. A common way command-line programs interact with one another is by accepting input from the standard input (STDIN) stream.

Adding a feature

Let’s add one last feature to the program: the ability to add new tasks via STDIN, allowing our users to pipe new tasks from other command-line tools.

To start this update, we add three new libraries to our main.go import list: bufio, io, and strings.

package main
import (
  "bufio"
  "flag"
  "fmt"
  "io"
  "os"
  "strings"
  "pragprog.com/rggo/interacting/todo"
)

We’ll use:

  • The bufio package to read data from the STDIN input stream.
  • The io package to use the io.Reader interface.
  • The function Join() from the strings package to join command-line arguments to compose a task name.

Next, we’ll create a new helper function called getTask() that will determine where to get the input task from. This function leverages Go interfaces again by accepting the io.Reader interface as input. In Go, it’s a good practice to take interfaces as function arguments instead of concrete types. This approach increases the flexibility of ...