Invocations

Thor comes with an invocation-dependency system as well, that allows a task to be invoked only once. For example:

class Counter < Thor
  desc "one", "Prints 1 2 3"
  def one
    puts 1
    invoke :two
    invoke :three
  end

  desc "two", "Prints 2 3"
  def two
    puts 2
    invoke :three
  end

  desc "three", "Prints 3"
  def three
    puts 3
  end
end

When invoking the task one:

thor counter:one

The output is

1
2
3

which means that the three task was invoked only once.

Notice invocations do not share the same object. i.e, Thor will instantiate Counter once to invoke the task one, then, it instantiates another to invoke the task two and another for task three. This allows options and arguments to be parsed again. For example, if two and three have different options and both of them were given to the command line, calling invoke enables them to be parsed each time and used accordingly by each task.

Tasks may also be invoked from other classes and options may be passed to invocations. For example:

class A < Thor
  desc "list LINE", "Does A stuff"
  method_option :line, :type => :string, :required => false
  def list
    unless options[:line].nil?
      puts "Line option is #{options[:line]}"
    else
      puts "Line option wasn't passed"
    end
  end
end

class B < Thor
  desc "dig NAME", "Does B stuff"
  method_option :name, :type => :string
  def dig
    invoke 'a:list', [], :line => options[:name]
  end
end

$ thor a:list --line foo
Line option is foo
$ thor a:list
Line option wasn't passed
$ thor b:dig --name bar
Line option is bar

If a task needs to be invoked more than once, the method may be called directly instead of using invocations. This is useful for situations such as setting up and tearing down test infrastructure in between test suites. For instance:

class Tests < Thor
  desc('all', 'run all tests')
  def all
    setup()
    invoke :some_test_suite
    teardown()
    setup()
    invoke :some_other_test_suite
    teardown()
    # etc.
  end 

  desc('setup', 'set up the test database')
  def setup
    # some setup tasks here
  end

  desc('teardown', 'tear down the test database')
  def teardown
    # some teardown tasks here
  end
end

Be sure to check the documentation for the Thor class for more info.