Python中__call__用法实例

#call.py 一个class被载入的情况下。
class Next:
  List = []
  
  def __init__(self,low,high) :
    for Num in range(low,high) :
      self.List.append(Num ** 2)
  
  def __call__(self,Nu):
    return self.List[Nu]

b = Next(1,7)
print b.List
print b(2)

[1, 4, 9, 16, 25, 36]
9

b = Next
b(1,7)
print b.List
print b(2)
$python ./call.py
[1, 4, 9, 16, 25, 36]

Traceback (most recent call last):
 File "cal.py", line 17, in <module>
  print b(2) 
TypeError: __init__() takes exactly 3 arguments (2 given)

b = Next

Next(1,7)
print Next.List
print Next(2)