Python Design Patterns - Builder
Builder Pattern是一种独特的设计模式，有助于使用简单对象构建复杂对象并使用算法方法。 这种设计模式属于创作模式的范畴。 在此设计模式中，构建器类按步骤构建最终对象。 此构建器独立于其他对象。
Builder模式的优点
它提供了清晰的分离，以及构造和表示由类创建的指定对象之间的唯一层。
它可以更好地控制所创建模式的构建过程。
它提供了改变对象内部表示的完美场景。
如何实现构建器模式？
在本节中，我们将学习如何实现构建器模式。
class Director:
__builder = None
def setBuilder(self, builder):
self.__builder = builder
def getCar(self):
car = Car()
# First goes the body
body = self.__builder.getBody()
car.setBody(body)
# Then engine
engine = self.__builder.getEngine()
car.setEngine(engine)
# And four wheels
i = 0
while i < 4:
wheel = self.__builder.getWheel()
car.attachWheel(wheel)
i += 1
return car
# The whole product
class Car:
def __init__(self):
self.__wheels = list()
self.__engine = None
self.__body = None
def setBody(self, body):
self.__body = body
def attachWheel(self, wheel):
self.__wheels.append(wheel)
def setEngine(self, engine):
self.__engine = engine
def specification(self):
print "body: %s" % self.__body.shape
print "engine horsepower: %d" % self.__engine.horsepower
print "tire size: %d\'" % self.__wheels[0].size
class Builder:
def getWheel(self): pass
def getEngine(self): pass
def getBody(self): pass
class JeepBuilder(Builder):
def getWheel(self):
wheel = Wheel()
wheel.size = 22
return wheel
def getEngine(self):
engine = Engine()
engine.horsepower = 400
return engine
def getBody(self):
body = Body()
body.shape = "SUV"
return body
# Car parts
class Wheel:
size = None
class Engine:
horsepower = None
class Body:
shape = None
def main():
jeepBuilder = JeepBuilder() # initializing the class
director = Director()
# Build Jeep
print "Jeep"
director.setBuilder(jeepBuilder)
jeep = director.getCar()
jeep.specification()
print ""
if __name__ == "__main__":
main()
输出 (Output)
上述程序生成以下输出 -
