python - 当类的 __init__ 需要参数时构造不带参数的对象(矩形)

Question

我正在做一项作业，需要一个Rectangle类来计算给定的面积和周长。我们已经获得了 main() 函数，并且必须围绕它进行构建。它似乎一直运行到它所说的 b = Rectangle() 为止

requires exactly 3 arguments.

这是我的代码:

class Shape(object):

    def __init__(self):
        pass
    def area():
        pass
    def perimeter():
        pass

class Rectangle(Shape):

    def __init__(self, width, height):
        Shape.__init__(self)
        self.width = width
        self.height = height

    def area(self):
        area = self.height * self.width
        return area

    def perimeter(self):
        perimeter = 2*(self.width+self.height)
        return perimeter

    def getStats():
        print "Width:      %d" % b.width
        print "Height:     %d" % b.height
        print "Area:       %d" % b.area
        print "Perimeter:  %d" % b.perimeter

def main():

    print "Rectangle a:"
    a = Rectangle(5, 7)
    print "area:      %d" % a.area()
    print "perimeter: %d" % a.perimeter()

    print ""
    print "Rectangle b:"
    b = Rectangle()  
    b.width = 10
    b.height = 20
    print b.getStats()

main()

如何在不改变主函数的情况下让第二个矩形工作？

Answer 1

了解 python 对 default arguments 的支持对于“构造函数”...类似于

   def __init__(self, width = 0, height = 0)