python 重载

class Vector:
    def __init__(self,x=0.0, y=0.0, z=0.0):
        self.x = x
        self.y = y
        self.z = z
    def __str__(self):
        return 'Vector({0},{1},{2})'.format(self.x,self.y,self.z)

    def __neg__(self):
        return Vector(-self.x,-self.y,self.z)

    def __add__(self, other):
        return Vector(self.x + other.x,self.y + other.y, self.z + other.z)

    def __sub__(self, other):
        return Vector(self.x - other.x,self.y + other.y, self.z + other.z)

    def __mul__(self, other):
        return Vector(other * self.x , other * self.y , other * self.z)

    def __rmul__(self, other):
        return Vector(other * self.x , other * self.y , other * self.z)



if __name__ == '__main__':
    v1 = Vector(1,2,3)
    v2 = Vector(4,5,6)
    print('-v1={}'.format(-v1))
    print('v1+v2={}'.format(v1+v2))
    print('v1-v2={}'.format(v1-v2))
    print('v1*2={}'.format(v1*2))
    print('2*v1={}'.format(2*v1))