from math import hypot

class Vector:

def __init__(self,x=0,y=0):

self.x=x

self.y=y

# 把一个对象以字符串形式表现出来以便辨认

def __repr__(self):

return '__repr__ Vector(%s, %s)'% (self.x,self.y)

def __abs__(self):

# Return the Euclidean distance, sqrt(x*x + y*y).

return hypot(self.x, self.y)

def __bool__(self):

# return bool(abs(self))

# 更高效的做法

return bool(self.x or self.y)

# 算术运算符 +

def __add__(self, other):

x=self.x+other.x

y=self.y+other.y

return Vector(x,y)

# 算术运算符 *

def __mul__(self, scalar):

return Vector(self.x*scalar,self.y*scalar)

v1=Vector(1,2)

v2=Vector(3,4)

print(v1+v2)

print(v1*5)

print(abs(v2))

print(v1)

v3=Vector()

print(bool(v3))