运算重新定义
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算数运算符
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| __add__(self, other) | 定义加法的行为：+ |
| __sub__(self, other) | 定义减法的行为：- |
| __mul__(self, other) | 定义乘法的行为：* |
| __truediv__(self, other) | 定义真除法的行为：/ |
| __floordiv__(self, other) | 定义整数除法的行为：// |
| __mod__(self, other) | 定义取模算法的行为：% |
| __divmod__(self, other) | 定义当被 divmod() 调用时的行为 |
| __pow__(self, other[, modulo]) | 定义当被 power() 调用或 ** 运算时的行为 |
| __lshift__(self, other) | 定义按位左移位的行为：<< |
| __rshift__(self, other) | 定义按位右移位的行为：>> |
| __and__(self, other) | 定义按位与操作的行为：& |
| __xor__(self, other) | 定义按位异或操作的行为：^ |
| __or__(self, other) | 定义按位或操作的行为：| |
更多 https://fishc.com.cn/forum.php?mod=viewthread&tid=48793
1 >>> class New_int(int):
2 def __add__(self, other):
3 return int.__sub__(self, other)
4 def __sub__(self, other):
5 return int.__add__(self, other)
6
7
8 >>> a = New_int(3)
9 >>> b = New_int(5)
10 >>> a + b
11 -2
12 >>> a - b
13 8
14
15
16 >>> class Try_int(int):
17 def __add__(self, other):
18 return int(self) - int(other)
19 def __sub__(self, other):
20 return int(self) + int(other)
21
22
23 >>> a = Try_int(3)
24 >>> b = Try_int(5)
25 >>> a+b
26 -2
反运算
当左操作数不支持相应的操作时被调用
1 >>> class Nint(int):
2 def __radd__(self, other):
3 return int.__sub__(self, other)
4
5
6 >>> a = Nint(5)
7 >>> b = Nint(3)
8 >>> a+b
9 8
10 >>> 1+b
11 2执行1+b时，由于1与b的加法不存在，则会反调用b的加法变成b+1的形式执行__add__
故如果需要使结果不变应该调换return里的self和other的位置
>>> class Nint(int):
def __radd__(self, other):
return int.__sub__(other, self)
>>> a = Nint(5)
>>> b = Nint(3)
>>> a+b
8
>>> 1+b
-2
简单定制计时器
实现直接输出字符的方法
>>> class A():
def __repr__(self):
return "abc"
>>> a = A()
>>> a
abc
import time as t
class MyTimer():
def __init__(self):
self.unit = ['年', '月', '天', '小时', '分钟', '秒']
self.prompt = "未开始计时！"
self.lasted = []
self.start0 = 0
self.stop0 = 0
def __str__(self):
return self.prompt
__repr__ = __str__
def __add__(self, other):
prompt = "总共运行了"
result = []
for index in range(6):
result.append(self.lasted[index] + other.lasted[index])
if result[index]:
prompt += (str(result[index]) + self.unit[index])
return prompt
#开始计时
def start(self):
self.start0 = t.localtime()
self.prompt = "请先停止计时"
print("计时开始...")
#停止计时
def stop(self):
if not self.start0:
print("请先开始计时")
else:
self.stop0 = t.localtime()
self._calc()
print("计时结束！")
#内部方法，计算运行时间
def _calc(self):
self.lasted = []
self.prompt = "总共运行了"
for index in range(6):
self.lasted.append(self.stop0[index] - self.start0[index] )
if self.lasted[index]:
self.prompt += (str(self.lasted[index]) + self.unit[index])
print(self.prompt)
#下一轮初始化
self.start0 = 0
self.stop0 = 0
来源：oschina
链接：https://my.oschina.net/u/4396273/blog/3622093