Relaunch current script in MacRuby

gistfile1.rb

module Env
  MACRUBY_FRAMEWORK_BIN = 'MacRuby.framework/Versions/Current/usr/bin/macruby'
  MACRUBY_CANDIDATES = [
    "/System/Library/PrivateFrameworks/#{MACRUBY_FRAMEWORK_BIN}",
    "/Library/Frameworks/#{MACRUBY_FRAMEWORK_BIN}"
  ]

  def self.find_macruby
    MACRUBY_CANDIDATES.each do |path|
      return path if File.exist?(path)
    end
    last_resort = `which macruby`
    last_resort.empty? ? nil : last_resort
  end

  def self.macruby?
    return false unless Kernel.const_defined?(:RUBY_ENGINE)
    Kernel.const_get(:RUBY_ENGINE) == 'macruby'
  end

  def self.relaunch_in_macruby!(fatal=true)
    return if self.macruby?
    macruby = self.find_macruby
    fail 'Could not find MacRuby' if macruby.nil? and fatal

    args = [__FILE__] + ARGV
    Kernel.exec(macruby, *args)
  end
end