[英]python, inheritance, super() method
I'm new to python, I have the code below which I just can't get to work:- This is inheritance, I have a circle base class and I inherit this within a circle
class (just single inheritance here). 我是python的新手,下面有一些我无法使用的代码:-这是继承,我有一个圈子基类,我在一个
circle
类中继承了它(这里只是单个继承)。
I understand the issue is within the ToString()
function within the circle
class, specifically the line, text = super(Point, self).ToString() +..
which requires at least a single argument, yet I get this: 我知道问题出在
circle
类的ToString()
函数内,特别是线text = super(Point, self).ToString() +..
这至少需要一个参数,但是我得到了:
AttributeError: 'super' object has no attribute 'ToString'
I know super
has no ToString
attribute, but the Point
class does - 我知道
super
没有ToString
属性,但是Point
类确实有-
My code: 我的代码:
class Point(object):
x = 0.0
y = 0.0
# point class constructor
def __init__(self, x, y):
self.x = x
self.y = y
print("point constructor")
def ToString(self):
text = "{x:" + str(self.x) + ", y:" + str(self.y) + "}\n"
return text
class Circle(Point):
radius = 0.0
# circle class constructor
def __init__(self, x, y, radius):
super(Point, self) #super().__init__(x,y)
self.radius = radius
print("circle constructor")
def ToString(self):
text = super(Point, self).ToString() + "{radius = " + str(self.radius) + "}\n"
return text
shapeOne = Point(10,10)
print( shapeOne.ToString() ) # this works fine
shapeTwo = Circle(4, 6, 12)
print( shapeTwo.ToString() ) # does not work
You need to pass in the Circle
class instead: 您需要传递
Circle
类:
text = super(Circle, self).ToString() + "{radius = " + str(self.radius) + "}\n"
super()
will look through the base classes of the first argument to find the next ToString()
method, and Point
doesn't have a parent with that method. super()
将遍历第一个参数的基类以找到下一个ToString()
方法,并且Point
没有该方法的父级。
With that change, the output is: 进行此更改后,输出为:
>>> print( shapeTwo.ToString() )
{x:0.0, y:0.0}
{radius = 12}
Note that you make the same mistake in your __init__
; 注意,您在
__init__
犯了同样的错误; you are not calling the inherited __init__
at all. 您根本没有调用继承的
__init__
。 This works: 这有效:
def __init__(self, x, y, radius):
super(Circle, self).__init__(x ,y)
self.radius = radius
print("circle constructor")
and then the output becomes: 然后输出变为:
>>> shapeTwo = Circle(4, 6, 12)
point constructor
circle constructor
>>> print( shapeTwo.ToString() )
{x:4, y:6}
{radius = 12}
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