argument

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	The name of the argument.
options	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/bundler/vendor/thor/lib/thor/base.rb, line 232
      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 << Bundler::Thor::Argument.new(name, options)
      end