class Thor::Argument

def initialize(name, description=nil, required=true, type=:string, default=nil, banner=nil)
  class_name = self.class.name.split("::").last
  raise ArgumentError, "#{class_name} name can't be nil."                         if name.nil?
  raise ArgumentError, "Type :#{type} is not valid for #{class_name.downcase}s."  if type && !valid_type?(type)
  @name        = name.to_s
  @description = description
  @required    = required || false
  @type        = (type || :string).to_sym
  @default     = default
  @banner      = banner || default_banner
  validate! # Trigger specific validations
end