1_facade.py

class Buffer:
  def __init__(self, width=30, height=20):
    self.width = width
    self.height = height
    self.buffer = [' '] * (width*height)

  def __getitem__(self, item):
    return self.buffer.__getitem__(item)

  def write(self, text):
    self.buffer += text

class Viewport:
  def __init__(self, buffer=Buffer()):
    self.buffer = buffer
    self.offset = 0

  def get_char_at(self, index):
    return self.buffer[self.offset+index]

  def append(self, text):
    self.buffer += text

class Console:
  def __init__(self):
    b = Buffer()
    self.current_viewport = Viewport(b)
    self.buffers = [b]
    self.viewports = [self.current_viewport]

  # high-level
  def write(self, text):
    self.current_viewport.buffer.write(text)

  # low-level
  def get_char_at(self, index):
    return self.current_viewport.get_char_at(index)


if __name__ == '__main__':
  c = Console()
  c.write('hello')
  ch = c.get_char_at(0)