Making CLI app with ruby

I'm Huy

@huydx

I'm software developer base in Tokyo, Japan

Blogger at http://ktmt.github.io

What is CLI app

• CLI stand for command-line interface

• Some examples of CLI app

$git log --UI --word-diffGit

$grep -c false /etc/passwdGrep

mysql-cli >mysql

ruby-irb 2.1.3 :001 > 1 + 1 #2

single line shell

interactive shell

Why making CLI app

• We are programmers, we live in terminal

• Good CLI tool make our life easier

• Using terminal make us feel like a god

Introduce Thor

erikhuda/thor"Thor is a simple and

efficient tool for building

self-documenting

command line utilities."

Using thor, we can build single command line app with ease

Let's make a simple THOR app (live coding)

But.....

Single line shell app is somewhat boring~~~

Let's make interactive shell app using REPL

• REPL stands for read–eval–print loop

• REPL can simply be a loop !

!

• Using REPL makes our app more

interactive

while (line=gets) do #do something with line end

Writing complex interactive shell from the

scratch is hard...

Introduce Readline

"The GNU Readline library

provides a set of functions for

use by applications that allow

users to edit command lines as

they are typed in. "

GNU readline binding for ruby is a built in STL!!!!!!

http://cnswww.cns.cwru.edu/php/chet/readline/rltop.html

What Readline capable of

• Customize-able prompt!!!

• Manage-able history

• Auto completion

• Interchange-able editing mode (vim, emacs)

Let's make a simple Readline app (live coding)

Some tips to make better CLI app

• Do one thing

• Playing well with Others (streams, exit code)

• Have clear, concise purpose

• Perfect documentation

FA C Yfacebook command line app

huydx.com/facy

This is how my app looks like

R E P O AT H T T P : / / H U Y D X . C O M / FA C Y

Thank you for listening!!!