Method: Thor::Base::ClassMethods#argument

Defined in:

lib/thor/base.rb

#argument(name, options = {}) ⇒ Object

Adds an argument to the class and creates an attr_accessor for it.

Arguments are different from options in several aspects. The first one is how they are parsed from the command line, arguments are retrieved from position:

thor command NAME

Instead of:

thor command --name=NAME

Besides, arguments are used inside your code as an accessor (self.argument), while options are all kept in a hash (self.options).

Finally, arguments cannot have type :default or :boolean but can be optional (supplying :optional => :true or :required => false), although you cannot have a required argument after a non-required argument. If you try it, an error is raised.

Parameters

name<Symbol>

The name of the argument.

options<Hash>

Described below.

Options

:desc - Description for the argument. :required - If the argument is required or not. :optional - If the argument is optional or not. :type - The type of the argument, can be :string, :hash, :array, :numeric. :default - Default value for this argument. It cannot be required and have default values. :banner - String to show on usage notes.

Errors

ArgumentError

Raised if you supply a required argument after a non required one.

# File 'lib/thor/base.rb', line 261

def argument(name, options = {})
  is_thor_reserved_word?(name, :argument)
  no_commands { attr_accessor name }

  required = if options.key?(:optional)
    !options[:optional]
  elsif options.key?(:required)
    options[:required]
  else
    options[:default].nil?
  end

  remove_argument name

  if required
    arguments.each do |argument|
      next if argument.required?
      raise ArgumentError, "You cannot have #{name.to_s.inspect} as required argument after " \
                          "the non-required argument #{argument.human_name.inspect}."
    end
  end

  options[:required] = required

  arguments << Thor::Argument.new(name, options)
end