GoF design pattern - Bridge

bridge.py

# -*- coding: utf-8 -*-

"""http://en.wikibooks.org/wiki/Computer_Science_Design_Patterns/Bridge_Pattern#Python"""

# ConcreteImplementor 1/2
class DrawingAPI1(object):
	def draw_circle(self, x, y, radius):
		print('API1.circle at {}:{} radius {}'.format(x, y, radius))


# ConcreteImplementor 2/2
class DrawingAPI2(object):
	def draw_circle(self, x, y, radius):
		print('API2.circle at {}:{} radius {}'.format(x, y, radius))


# Refined Abstraction
class CircleShape(object):
	def __init__(self, x, y, radius, drawing_api):
		self._x = x
		self._y = y
		self._radius = radius
		self._drawing_api = drawing_api

	# low-level i.e. Implementation specific
	def draw(self):
		self._drawing_api.draw_circle(self._x, self._y, self._radius)

	# high-level i.e. Abstraction specific
	def scale(self, pct):
		self._radius *= pct


def main():
	shapes = (
		CircleShape(1, 2, 3, DrawingAPI1()),
		CircleShape(5, 7, 11, DrawingAPI2())
		)

	for shape in shapes:
		shape.scale(2.5)
		shape.draw()


if __name__ == '__main__':
	main()