python3中的类如何使用truediv？

Question

我有这样的代码：

# Imports
from __future__ import print_function
from __future__ import division
from operator import add,sub,mul,truediv


class Vector:
   def __init__(self, a, b):
      self.a = a
      self.b = b

   def __str__(self):
      return 'Vector (%d, %d)' % (self.a, self.b)

   def __add__(self,other):
      return Vector(self.a + other.a, self.b + other.b)

   def __sub__(self,other):
       return Vector(self.a - other.a, self.b - other.b)

   def __mul__(self,other):
       return Vector(self.a * other.a, self.b * other.b)

   # __div__ does not work when  __future__.division is used   
   def __truediv__(self, other):
       return Vector(self.a / other.a, self.b / other.b)

v1 = Vector(2,10)
v2 = Vector(5,-2)
print (v1 + v2)
print (v1 - v2)
print (v1 * v2)
print (v1 / v2) # Vector(0,-5)

print(2/5) # 0.4
print(2//5) # 0

我期待的是 Vector(0.4, -5 ) 而不是 Vector(0,-5)，我该如何实现？

一些有用的链接是：
https://docs.python.org/2/library/operator.html
http://www.tutorialspoint.com/python/python_classes_objects.htm

Answer 1

值正确但打印错误，因为您在此处将结果转换为 int：

def __str__(self):
    return 'Vector (%d, %d)' % (self.a, self.b)
    #             ---^---

您可以将其更改为：

def __str__(self):
    return 'Vector ({0}, {1})'.format(self.a, self.b)

这将打印：

Vector (0.4, -5.0)

python3中的类如何使用truediv？

How to use truediv for classes in python3?

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python-3.x