Shelley

A gem for converting your classes and method into a shell supporting nested commands, autocomplete and history.

Installation

Add this line to your application's Gemfile:

gem 'shelley'

And then execute:

$ bundle

Or install it yourself as:

$ gem install shelley

Usage

A simple shell

class Calculator
  def initialize
    @value = 0
  end

  def add(n)
    @value += n.to_i
  end

  def subtract(n)
    @value -= n.to_i
  end

  def multiply_by(n)
    @value *= n.to_i
  end

  def divide_by(n)
    @value /= n.to_i
  end

  def result
    puts @value
  end
end

command_registry = Shelley::CommandRegistry.new
command_registry.add_command(Calculator.new)
shell = Shelley::InteractiveShell.new(command_registry)
shell.start

Sample output

> add 3
> result
3
> add 5
> subtract 2
> result
6
> divide_by 3
> result
2
> multiply_by 10
> result
20
> divide_by 0
divided by 0
>

A shell with subcommands

class Timer
  def initialize
    @started_at = nil
    @elapsed = 0
  end

  def start
    return unless @started_at.nil?
    @started_at = Time.now
  end

  def stop
    return if @started_at.nil?
    @elapsed += Time.now - @started_at
    @started_at = nil
  end

  def elapsed
    elapsed = @elapsed
    elapsed += (Time.now - @started_at) unless @started_at.nil?
    puts elapsed
  end
end

command_registry = Shelley::CommandRegistry.new
command_registry.add_command(Calculator.new, 'calc')
command_registry.add_command(Timer.new, 'timer')
shell = Shelley::InteractiveShell.new(command_registry)
shell.start

Sample output

> calc add 1
> calc add 3
> timer start
> calc subtract 2
> calc result
2
> timer elapsed
10.156443773
> timer stop
> timer elapsed
12.239438967
> timer elapsed
12.239438967
> calc result
2

TODO

• Support for adding single methods
• Automatic argument convertion
• Argument autocomplete
• Refactor InteractiveShell and CommandRegistry in order to not expose the internal state of CommandRegistry