TypeError: missing arguments in custom Python class

Question

Why am I getting the following error in this python code?

class polygon:
    def __init__(self, sides):
        self.sides = sides

    def display_info_polygon(self):
        print("it contains 5 sides")
    
    def perimeter_of_polygon(self):
        perimeter = sum(self.sides)
        return perimeter
    
class triangle(polygon):
    def display_info_triangle(self):
        print("Triangle has 3 sides")
    
class square(polygon):
    def display_info_square(self):
        print("square has 4 sides")
    
triangle1 = triangle()
triangle1.display_info_triangle()

This is the Traceback:

Traceback (most recent call last): File "C:\Users\CISPL-ABHINITESH\PycharmProjects\pythonProject\venv\perimeter_polygon_inheritance.py", line 20, in triangle1 = triangle() TypeError: init() missing 1 required positional argument: 'sides'

DeadSec · Accepted Answer · 2021-03-16 10:20:20Z

2

You are trying to run a class that takes one agr polygon but you're not giving it that value that's why it displays an error.

Your code:

triangle1 = triangle()
triangle1.display_info_triangle()

How it should be:

triangle1 = triangle(<YOUR POLYGON VALUE>)
triangle1.display_info_triangle()

answered Mar 16, 2021 at 10:20

DeadSec

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Comments

Riedler · Accepted Answer · 2021-03-16 10:42:18Z

1

Read the Exception:

triangle1 = triangle() 
TypeError: __init__() missing 1 required positional argument: 'sides'

That means, when calling triangle(), the method __init__() of the parent class is called, which is missing one argument. So, the solution is to add that argument in the call:

triangle1 = triangle(3)

replace 3 with the value you want the argument sides to have.

answered Mar 16, 2021 at 10:42

Riedler

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Comments

Muhammad Huzaifa · Accepted Answer · 2021-03-16 12:14:47Z

0

triangle is inheriting polygon, so when you create an instance of triangle, the constructor of polygon is initiated, which takes an argument sides.

def __init__(self, sides):
      self.sides = sides

If you don't pass that argument, you will get an error. You should instantiate triangle by giving a sides value as an argument to the constructor like so:

triangle1 = triangle(7)

answered Mar 16, 2021 at 12:14

Muhammad Huzaifa

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