Question

I want make interactive application where user launches it and can do various task by typing commands (some kind of shell)

example:

./myapp.rb  
App says Hi  
Commands:   
  help - display help about command
  open - open task
  do - do action
Start>help open
  open <TaskName>
  opens specified task
Start>open Something  
Something>do SomeAction
  Success!
Something> (blinking cursor here)

I searched but couldn’t find any ruby gems that I could use specially for console interaction, so I’m about to my make my own…

I looked at Thor, but that’s not exactly as I want, maybe I could use it, but not sure…

it could look something like:

class Tasks
  attr_reader :opened_task

  desc "open <TaskName>", "opens specified task"
  def open(params)
  end

  desc "do <ActionName>", "do specified action"
  def do(params)
  end
end

tasks = Tasks.new
# theoretical Console class
console = Console.new
console.addCommand("open",tasks.method(:open),"open task")
console.addCommand("do",tasks.method(:do),"do action")
console.start("%s>",[*tasks.opened_task])

so my question is, what gems I could use to make such console class? maybe someone have already made something similar?
I plan using HighLine for input/output, but any other suggestion what could I use?

Answer 1

What you want is a REPL – Read → Evaluate → Print Loop.

IRB, for example, implements a REPL for the Ruby language.

Here’s a very simple implementation of your application’s REPL:

loop do
  Application::Console.prompt.display
  input = gets.chomp
  command, *params = input.split /\s/

  case command
  when /\Ahelp\z/i
    puts Application::Console.help_text
  when /\Aopen\z/i
    Application::Task.open params.first
  when /\Ado\z/i
    Application::Action.perform *params
  else puts 'Invalid command'
  end
end

\A and \z match the start of the string and the end of the string, respectively.