show the code for a Thor task

thorcat.rb

# thor install http://gist.github.com/50043.txt
# thor cat:task some:task
# thor cat:task thor:runner:install  # built-in tasks

require 'ruby2ruby'

class Cat < Thor
  $requires = []
  module ::Kernel
    def require_with_record(file)
      $requires << file if caller[1] =~ /thor\/runner/
      require_without_record file
    end
    alias_method :require_without_record, :require
    alias_method :require, :require_with_record
  end

  desc "task TASK", "output Ruby code for TASK"
  def task(meth)
    runner = Thor::Runner.new
    runner.send(:initialize_thorfiles, meth) # oh no private!
    cat_task(meth)
  end

  def cat_task(meth)
    task = Thor[meth]
    obj = task.klass.new
    unless obj.respond_to? task.meth
      raise Error, "The #{task.namespace false} namespace doesn't have a `#{task.meth}' task"
    end
    $requires += ['ruby2ruby'] if meth == 'cat:task'

    unless $requires.empty?
      puts $requires.map { |r| "require #{r.inspect}" }.join("\n"), "\n"
    end
    puts %{class #{task.klass.to_s.gsub(/^Thor::Tasks::/, "")} < Thor}
    puts %{  desc "#{task.usage}", "#{task.description}"}
    puts Ruby2Ruby.translate(task.klass, task.meth).gsub(/^/, "  ")
    puts "end"
  end
end