possibly foolish extension of String class to take optional parameters via a Hash

scary_string.rb

# I'm inviting suggestions for refactoring this initialize method---without losing the fact that it's a subclass of String

# should accept empty arguments;
# should accept a string, and set default attributes;
# should accept a string, with optional Hash args to set attributes;
# should raise an error if there is no String but there is a Hash


class ExtraString < String
  attr_accessor :optional_parameter
  
  def initialize(*args)
    if args[0].nil?
      super("")
    else
      raise ArgumentError, "ExtraString#new expected a String" unless args[0].kind_of?(String)
      super(args[0])
    end
    @optional_parameter = args[1].nil? ? 100 : args[1][:bar] || 100
  end
end


puts ExtraString.new.inspect                           # -> ""
puts ExtraString.new.optional_parameter                # -> 100

puts ExtraString.new("foo").inspect                    # -> "foo"
puts ExtraString.new("foo").optional_parameter         # -> 100

puts ExtraString.new("foo", bar:12).inspect            # -> "foo"
puts ExtraString.new("foo", bar:12).optional_parameter # -> 12

puts ExtraString.new("foo", baz:99).inspect            # -> foo
puts ExtraString.new("foo", baz:99).optional_parameter # -> 100

puts ExtraString.new(baz:99).inspect                   # raise an ArgumentError
puts ExtraString.new(bar:13).optional_parameter        # raise an ArgumentError