Python--042魔法方法：算术运算

游戏小虾米

Tip：


一，理论


二，应用
1
>>> class Try_int(int):
        def __add__(self, other):
                return self + other

       
>>> a = Try_int(3)
>>> b = Try_int(2)
>>> a + b
Traceback (most recent call last):
  File "<pyshell#34>", line 1, in <module>
    a + b
  File "<pyshell#30>", line 3, in __add__
    return self + other
  File "<pyshell#30>", line 3, in __add__
    return self + other
  File "<pyshell#30>", line 3, in __add__
    return self + other
  [Previous line repeated 327 more times]
RecursionError: maximum recursion depth exceeded while calling a Python object

2
>>> class Try_int(int):
        def __add__(self, other):
                return int(self) + int(other)              #还是没太理解，为啥转化整形之后就可以出结果，相加的不是方法吗

       
>>> a = Try_int(3)
>>> b = Try_int(2)
>>> a + b
5
三，课后练习