Missing 1 required positional argument: 'y'

Question

I have created a Python class:

class calculator:
    
    def addition(self,x,y):
        added = x + y
        print(added)
        
    def subtraction(self,x,y):
        sub = x - y
        print(sub)

    def multiplication(self,x,y):
        mult = x * y
        print(mult)

    def division(self,x,y):
        div = x / y
        print(div)

Now when I am calling the function like this:

calculator.addition(2,3)

I am getting an error:

addition() missing 1 required positional argument: 'y'

What is the problem? What could be the solution so that I can call it like addition(2,3)?

The problem is that you have to either create instance of class or declare methods as static. — Olvin Roght, Jul 25 '20 at 07:26
Read up on [TypeError: Missing one required positional argument](https://stackoverflow.com/a/50594457/7414759) and [Tutorial - 9.3. A First Look at Classes](https://docs.python.org/3/tutorial/classes.html#a-first-look-at-classes) — stovfl, Jul 25 '20 at 08:02

score 5 · Accepted Answer · edited Jan 25 '21 at 23:09

Python' classes have three types of methods:

Instance method

The instance method must pass the instance object as the first parameter to the method, which is self, like:

class calculator:
    
    def addition(self, x, y):
        added = x + y
        print(added)

c = calculator()        
c.addition(2, 3)

Class method

The class method use classmethod decorator and must pass the class object as the first parameter to the method, which is cls, like:

class calculator:
    
    @classmethod
    def addition(cls, x, y):
        added = x + y
        print(added)
    
calculator.addition(2, 3)

Static method

The static method doesn’t matter, just add an staticmethod decorator, like:

class calculator:
    
    @staticmethod
    def addition(x, y):
        added = x + y
        print(added)
    
calculator.addition(2, 3)

So, the last two ways can be your answer if you just want to call with a class object like calculator.addition(2, 3).

Than you so much for this explanation. Your solution cleared my doubt for classmethod and static methods. — Faraz Khan, Jul 25 '20 at 07:52

score 3 · Answer 2 · answered Jul 25 '20 at 07:28

3

You have to pass in the self variable by actually declaring an instance of this class, like this:

myCalculator = calculator()

myCalculator.addition(2,3)

Output should be: 5

answered Jul 25 '20 at 07:28

de_classified

1,927
1
15
19

score 1 · Answer 3 · answered Jul 25 '20 at 07:28

1

Please create a instance of the class first:

calculator_instance = calculator()

Then, you can call the function as calculator_instance.addition(2,3)

answered Jul 25 '20 at 07:28

blutab

181
8

score 0 · Answer 4 · answered Jul 25 '20 at 07:33

You should use the name "Calculator" for your class
When you call the function Caculator.addition you need 3 args (self, x, y) but you gived 2
You should write your function «addition(self,x,y):» like this «addition(self, x: int, y: int):»

If you just want the function addition write it not as a class methode but as a function. If you need write «calculator.addition(2,3)» first do calculator = Calculator()

score -1 · Answer 5 · answered Jul 25 '20 at 07:29

You just neet to delete self. Self will be used when you have __init __ function

class calculator:
    
    def addition(x,y):
        added = x + y
        print(added)
        
    def subtraction(x,y):
        sub = x - y
        print(sub)

    def multiplication(x,y):
        mult = x * y
        print(mult)

    def division(x,y):
        div = x / y
        print(div)

calculator.addition(2,3)

Missing 1 required positional argument: 'y'

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