我想给母亲班打电话,但收到以下消息:
Traceback (most recent call last):
File "***test.py", line 23, in <module>
for i in daughter:
File "***test.py", line 18, in __iter__
for i in super(Mother, self):
TypeError: 'super' object is not iterable
我认为这只是语法上的问题,我尝试不使用任何方法(仅对象本身)来调用super(母亲,自我)。这里的代码:
class Mother(object):
def __init__(self, upperBound):
self.upperBound = upperBound
def __iter__(self):
for i in range (self.upperBound):
yield i
class Daughter(Mother):
def __init__(self, multiplier, upperBound):
self.multiplier = multiplier
super(Daughter, self).__init__(upperBound)
def __iter__(self):
for i in super(Mother, self): # Here
yield i * self.multiplier
daughter = Daughter(2, 4)
for i in daughter:
print i
这里只是一个例子,我的目的是读取文件并逐行产生。然后,子类生成器解析所有行(例如,从该行中列出...)。
返回的代理对象super()
是不可迭代的,仅因为__iter__
MRO中有一个方法。您需要显式查找此类方法,因为这只会引起搜索:
for i in super(Daughter, self).__iter__():
yield i * self.multiplier
请注意,您需要super()
在当前类上使用,而不是在父类上使用。
super()
无法直接支持特殊方法,因为这些方法是由Python直接在类型上查找的,而不是实例。请参阅特殊方法查找新类:
对于新型类,只有在对对象的类型(而不是在对象的实例字典中)进行定义的情况下,才能保证对特殊方法的隐式调用可以正常工作。
type(super(Daughter, self))
是super
类型对象本身,它没有任何特殊方法。
演示:
>>> class Mother(object):
... def __init__(self, upperBound):
... self.upperBound = upperBound
... def __iter__(self):
... for i in range (self.upperBound):
... yield i
...
>>> class Daughter(Mother):
... def __init__(self, multiplier, upperBound):
... self.multiplier = multiplier
... super(Daughter, self).__init__(upperBound)
... def __iter__(self):
... for i in super(Daughter, self).__iter__():
... yield i * self.multiplier
...
>>> daughter = Daughter(2, 4)
>>> for i in daughter:
... print i
...
0
2
4
6
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