Boson is a modular command/task framework. Thanks to its rich set of plugins, it differentiates itself from rake and thor by being usable from irb and the commandline, having automated views generated by hirb and allowing libraries to be written as plain ruby. Works with on all major rubies for ruby >= 1.9.2

New Boson

Starting with 1.0, boson has changed significantly. Please read the upgrading doc if you have an older version or if your reading about boson predates 2012.

Boson has been rewritten to have a smaller core (no dependencies) with optional plugins to hook into its various features. The major focus of 1.0 has been to provide an easy way for third-party gems to create their executable and define subcommands with options.


Nicely formatted docs are available here.

Example Executable

For a gem with an executable, bin/cow:

#!/usr/bin/env ruby
require 'boson/runner'

class CowRunner < Boson::Runner
  option :urgent, type: :boolean
  def say(text, options={})
    text.capitalize! if options[:urgent]
    puts text

  def moo
    puts "MOOOO"


You can now execute cow with say and moo subcommands:

$ cow say hungry
$ cow moo
# use say's urgent option
$ cow say hungry -urgent

You'll notice that this syntax is powerful and concise and is very similar to thor's API. Subcommands map to ruby methods and the class represents the executable.

For some examples of executables see vimdb or tag.

Comparison to Thor

Since boson and it's rewrite are both heavily inspired by thor, it makes sense to compare them.

First, what I consider pros boson has over thor. Boson

Now for pros thor has over boson. Thor

Converting From Thor

Writing Plugins

A Boson plugin is a third-party library that extends Boson through its extension API. Any Boson class/module that includes or extends a module named API or APIClassMethods provides an extension API. Examples of such classes are Boson::BareRunner, Boson::Command, Boson::Inspector and Boson::Library. As an example, let us extend what any boson-based executable does first, extend Boson::BareRunner.start:

module Boson
  module CustomStartUp
    def start(*)
      # additional startup

Boson::BareRunner.extend Boson::CustomStartUp

Notice that extend was used to extend a class method. To extend an instance method you would use include. Also notice that you use super in an overridden method to call original functionality. If you don't, you're possibly overridden existing functionality, which is fine as long as you know what you are overriding.

If you want to gemify your plugin, name it boson-plugin_name and put it under lib/boson/plugin_name. The previous example would go in lib/boson/custom_startup.rb. To use your plugin, a user can simply require your plugin in their executable.

For many plugin examples, see boson-more.

Using a Plugin

To use a plugin, just require it. For an executable:

require 'boson/runner'
require 'boson/my_plugin'


For the boson executable, just require the plugins in ~/.bosonrc.

Extending Your Executables

Boson allows for custom default options and commands. This means you can add your own defaults in a plugin and use them across your executables.

To add a custom default command, simply reopen Boson::DefaultCommandsRunner:

class Boson::DefaultCommandsRunner
  desc "whoomp"
  def whoomp
    puts "WHOOMP there it is!"

To add a custom global option, add to Boson::Runner::GLOBAL_OPTIONS:

  verbose: {type: :boolean, desc: "Verbose description of loading libraries"}

Custom global options are defined in the same format as options for a command.


Please report them on github. If the issue is about upgrading from old boson, please file it in boson-more.


See here


Motivation for the new boson is all the damn executables I'm making.


Boson stands on the shoulders of these people and their ideas: