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 ruby >= 1.9.2
Starting with 1.0, boson has changed significantly. Please read the upgrading doc if you have an older version or if you're 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.
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
end
def moo
puts "MOOOO"
end
end
CowRunner.start
You can now execute cow with say and moo subcommands:
$ cow say hungry
hungry
$ cow moo
MOOOO
# use say's urgent option
$ cow say hungry -urgent
HUNGRY
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.
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
- is designed to handle plugins. This means it core parts are extendable by modules and core components like commands can have arbitrary metadata associated with them.
- has a rich set of plugins. See boson-more.
- has commands that are easily testable. Whereas thor has options that automagically
appear in command methods, boson explicitly passes options to its command
method as a hash i.e.
MyRunner.new.subcommand(arg, verbose: true)
. This also allows commands to just be called as ruby, with no magic to consider. - supports custom-user option types i.e. creating a Date option type. See Boson::Options.
- supports custom method decorators i.e. methods like desc that add functionality to a command. While boson supports option, options, desc and config out of the box, users can create their own.
- automatically creates usage for your subcommand. With thor you need to
manually define your usage with desc:
desc "SOME USAGE", "SOME DESCRIPTION"
- is lenient about descriptions. Describe commands at your leisure. With thor you must define a desc.
- has a smaller blacklist for command names i.e. just Kernel + Object method names. Thor has a bigger blacklist due to its design.
Now for pros thor has over boson. Thor
- is widely used and thus has been community QAed thoroughly.
- supports generators as a major feature.
- is more stable as its feature set is mostly frozen.
- is used by rails and thus is guaranteed support for some time.
- supports ruby 1.8.7.
- TODO: I'm sure there's more
The most common way to write a plugin is to extend one of the many method hooks available. Any methods that are defined in an API or APIClassMethods module are extendable. For example, if you want to extend what any boson-based executable does first, extend BareRunner.start:
module CustomStartUp
def start(*)
super
# additional startup
end
end
BareRunner.extend 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.
For many plugin examples, see boson-more.
Please report them on github.
Motivation for the new boson is all the damn executables I'm making.
Boson stands on the shoulders of these people and their ideas:
- Contributors: @mirell, @martinos
- Yehuda Katz for Thor and its awesome option parser (Boson::OptionParser).
- Daniel Berger for his original work on thor's option parser.
- Chris Wanstrath for inspiring Boson's libraries with Rip's packages.