the adapter pattern

british_text_adapter.rb

class BritishTextObjectAdapter < TextObject
  def initialize(bto)
    @bto = bto
  end

  def text
    return @bto.string
  end

  def size_inches
    return @bto.size_mm / 25.4
  end

  def color
    return @bto.colour
  end
end

british_text_object.rb

class BritishTextObject
  attr_reader :string, :size_mm, :colour

  # ....

end

call_encrypt.rb

reader = File.open('foo.txt')
writer = File.open('foo.encrypted', 'w')
encrypter = Encrypter.new('the secret key')
encrypter.encrypt(reader, writer)

encrpyt.rb

encrypter = Encrypter.new('OURSTRING')
reader = StringIOAdapter.new('This is our string')
writer = File.open('out.txt', 'w')
encrypter.encrpyt(reader, writer)

encrypter.rb

# encrypter.rb

class Encrypter
  def initialize(key)
    @key = key
  end

  def encrypt(reader, writer)
    key_index = 0
    until reader.eof?
      clear_char = reader.getc
      encrypted_char = clear_char ^ @key[key_index]
      writer.putc(encrypted_char)
      key_index = (key_index + 1) % @key.size
    end
  end
end

main.rb

# main.rb

require './renderer'
require './text_object'
require './british_text_object'


# === Modify the BritishTextObject class === #
# Extend the BritishTextObject to include the methods that the Renderer class requires

class BritishTextObjects
  def color
    return colour
  end

  def text
    return string
  end

  def size_inches
    return size_mm / 25.4
  end
end

mod_main.rb

# main.rb
....

# === Another way to achieve modifying a single instace === #

def bto.color
  colour
end

def bto.text
  string
end

def bto.size_inches
  return size_mm/25.4
end

modify.rb

# main.rb
...
# === Modify a Single Instance === #
#
bto = BritishTextObject.new('test', 25.4, :yellow)

class << bto
  def color
    colour
  end

  def text
    string
  end

  def size_inches
    return size_mm/25.4
  end
end

renderer.rb

class Renderer
  def render(text_object)
    text = text_object.text
    size = text_object.size_inches
    color = text_object.color

    # render the text
  end
end

string_io_adapter.rb

class StringIOAdapter
  def initialize(string)
    @string = string
    @position = 0
  end

  def getc
    if @position >= @string.length
      raise EOFError
    end
    ch = @string[@position]
    @position += 1
    return ch
  end

  def eof?
    return @position >= @string.length
  end
end

text_object.rb

class TextObject
  attr_reader :text, :size_inches, :color

  def initialize(text, size_inches, color)
    @text = text
    @size_inches = size_inches
    @color = color
  end
end