how to make a temporary object from withing the class function in python?

Question

I'm writing this code and there is a need to send objects as parameters in functions. My problem is one of the objects needs to be resued with its original values but as I need to return an object from the functions.

I don't know how I can send the answer and keep the original values in the object safe for reuse. Is there any way to make an object from the class declaration itself?

import math

class Points(object):
 def __init__(self, x, y, z):
    self.x = x
    self.y = y
    self.z = z


def __sub__(self, no):
    
    no.x = no.x - self.x
    no.y = no.y - self.y
    no.z = no.z - self.z
    
    return(no)

def dot(self, no):
    ans = (self.x * no.x)+(self.y * no.y)+(self.z * no.z)
    return ans

def cross(self, no):
    x = (self.y * no.z)-(self.z * no.y)
    y = (self.x * no.z)-(self.z * no.x)
    z = (self.x * no.y)-(self.y * no.x)
    self.x = x
    self.y = y
    self.z = z
    return(self)
    
def absolute(self):
    return pow((self.x ** 2 + self.y ** 2 + self.z ** 2), 0.5)

if __name__ == '__main__':
points = list()
for i in range(4):
    a = list(map(float, input().split()))
    points.append(a)

a, b, c, d = Points(*points[0]), Points(*points[1]), Points(*points[2]), Points(*points[3])
x = (b - a).cross(c - b)
y = (c - b).cross(d - c)
angle = math.acos(x.dot(y) / (x.absolute() * y.absolute()))

print("%.2f" % math.degrees(angle))

I want to do something like:

def function_name(self,other)
  temp.x = self.x + other.x
  temp.y = self.y + other.y
  return temp

This way both input objects will have their original values but I don't know how to get that temp.

(1) Try using periods in your question to separate sentences. It is very hard to read and understand. (2) What is `temp`? Is it an instance of `Points`? If so, just create a new object and then return it. — DYZ, Oct 30 '20 at 05:18

score 2 · Accepted Answer · edited Oct 30 '20 at 09:45

Thanks everyone who helped. I got the answer to what I was looking. I wanted an object to act as a container that can store the class variables, and I didn't knew I can just make a new object of the class from within it!

import math
class Points(object):
    def __init__(self, x, y, z):
        self.x=x
        self.y=y
        self.z=z

    def __sub__(self, no):
        return  Points((self.x-no.x),(self.y-no.y),(self.z-no.z))

    def dot(self, no):
        return (self.x*no.x)+(self.y*no.y)+(self.z*no.z)

    def cross(self, no):
        return Points((self.y*no.z-self.z*no.y),(self.z*no.x-self.x*no.z),(self.x*no.y-self.y*no.x))
        
    def absolute(self):
        return pow((self.x ** 2 + self.y ** 2 + self.z ** 2), 0.5)

As you can see using points, i.e the constructor for class Points, I can store the result of any operations and can return it as an object while not altering my input objects.

Thanks man as English isn't my first language, My Grammar is weak! — PARTH PATEL, Nov 03 '20 at 03:58

score 1 · Answer 2 · answered Oct 30 '20 at 05:26

If what you're trying to do is reuse a variable that you have passed to a class object, you can just duplicate it in your __init__ statement, or in the function where you use it.

e.g

class Foo:
  
  def __init__(self, my_var1, my_var2):
    self.my_var1 = my_var1
    self.my_var2 = my_var2

  def bar(self):
    bar_var1 = self.my_var1
    bar_var2 = self.my_var2
    bar_var1 = bar_var1 + bar_var2
    return bar_var1

Although, I am a little confused by why you are attempting to return self in your cross function, as self is a class parameter, and you don't seem to be using it in its intended purpose. If you're confused about how you should be using self, a brief read through the python class tutorial might be helpful. However, barring that, I hope this answers your question.

how to make a temporary object from withing the class function in python?

2 Answers2