Python oop将一个对象作为参数传递，并在另一个对象的方法内部使用其方法

Question

I want to pass an object of the class as the argument in one of the methods of the same class.

There are some answers on Stack Overflow, but they embrace very simple examples without methods. Yes, I know, that passing an object is not different from passing an integer. The problem is that when I pass it as an argument in the same way as integer I have an error when I am calling the method of the class.

Here is my example.

The object of my class is a point. It has two attributes, which are x, y coordinates. I want to have a method, which will calculate a distance from the object to another object passed. I use getters to get the values of the attributes.

import math

class Point:
    """Point class, whose object is a point"""

    def __init__(self, m_x=0, m_y=0):
        self._x = m_x
        self._y = m_y

    @property
    def X(self):
        """X coordinate"""
        return self._x

    @X.setter
    def X(self, m_x):
        self._x = m_x

    @property
    def Y(self):
        """Y coordinate"""
        return self._y

    @Y.setter
    def Y(self, m_y):
        self._y = m_y

    def ToString(self):
        """Prints a string with coordinates"""
        print("Point x: {}, y: {}".format(self._x, self._y))

    def DistanceOrigin(self):
        """Calculates a distance to the origin of the coordinate axis (0,0)"""
        return math.sqrt((self._x ** 2) + (self._y ** 2))

    def Distance(self, m_object):
        """Calculates a distance to another object"""
        return math.sqrt(((self._x - m_object.X) ** 2) + (self._y - m_object.Y ** 2))

p = Point(3, 4)

p.ToString()
print(p.DistanceOrigin())

p.X = 2

print(p.X)

q = Point(2, 3)

q.Distance(p) # Here appears the error

The error appears in the last line.

line 34, in Distance
    return math.sqrt(((self._x - m_object.X) ** 2) + (self._y - m_object.Y ** 2))
ValueError: math domain error

So how to pass an object 1 as an argument to another object 2, so that I could use the methods object 1 in the method of the object 2?

Answer 1

    return math.sqrt(((self._x - m_object.X) ** 2) + (self._y - m_object.Y ** 2))

Should be:

    return math.sqrt(((self._x - m_object.X) ** 2) + ((self._y - m_object.Y) ** 2))

You forgot parentheses around Y difference.

Answer 2

the issue is with math.sqrt function . it does not accept negative numbers.

    return math.sqrt(((self._x - m_object.X) ** 2) + ((self._y - m_object.Y) ** 2))

is the correct way.