bridge.py

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

# ConcreteImplementor 1/2
class DrawingAPI1:
 def drawCircle(self, x, y, radius):
 print('API1.circle at {}:{} radius {}'.format(x, y, radius))
 
# ConcreteImplementor 2/2
class DrawingAPI2:
 def drawCircle(self, x, y, radius):
 print('API2.circle at {}:{} radius {}'.format(x, y, radius))
 
# Refined Abstraction
class CircleShape:
 def __init__(self, x, y, radius, drawingAPI):
 self.__x = x
 self.__y = y
 self.__radius = radius
 self.__drawingAPI = drawingAPI
 
 # low-level i.e. Implementation specific
 def draw(self):
 self.__drawingAPI.drawCircle(self.__x, self.__y, self.__radius)
 
 # high-level i.e. Abstraction specific
 def resizeByPercentage(self, pct):
 self.__radius *= pct
 
def main():
 shapes = (
 CircleShape(1, 2, 3, DrawingAPI1()),
 CircleShape(5, 7, 11, DrawingAPI2())
 )
 
 for shape in shapes:
 shape.resizeByPercentage(2.5)
 shape.draw()
 
if __name__ == "__main__":
 main()