CODEWITHSUNDEEP
pythonpython-3.x
Prashanth
Prashanth

Reputation: 141

Unable to call function with self

I'm writing a simple code snippet here, but unable to run the code

class test:
    def __init__(self):
        pass

    def functiona(self, a):
        b = a+0
        print(b)

    def functionb(self):
        a = 5
        self.functiona(a)

test.functionb('abc')

It errors out with "AttributeError: 'str' object has no attribute 'functiona'" Unable to call it with self. However, if I provide test.functiona(a) it works fine.

Few of other code samples works with self.function, how to solve this issue

Upvotes: 1

Views: 2968

Answers (4)

glglgl
glglgl

Reputation: 91039

test.functionb('abc') is a function call on the class, not on an instance.

I suppose it works if you do test().functionb('abc')?

The difference is:

  • In your case, you call the function object on the class. As it is not a staticmethod or classmethod, it is called with self = 'abc', a string. This string hasn't a method functiona().
  • In my case, the call operates on a class instance. Here, self is set to the instance you just created – and you get an error because it doesn't know where to pass the 'abc'.

Upvotes: 1

Prashanth
Prashanth

Reputation: 141

Problem lies in the call test.functionb('abc'). You are not using object of the class to call the method. So, the self parameter is not passed. Python considers, the first parameter to be self, and you passed 'abc' which is a string.

Use it like test().functionb('abc') , then the default first argument becomes the object of test - like functionb(test_ob, 'abc').

Upvotes: -1

Bendik Knapstad
Bendik Knapstad

Reputation: 1458

you can add the decorator @classmethod and then call it like you did

class test:
    def __init__(self):
        pass
    @classmethod
    def functiona(self, a):
        b = a+0
        print(b)
    @classmethod
    def functionb(self):
        a = 5
        self.functiona(a)

>>> test.functiona(1001)
>>> 1001
>>> test.functionb()
>>> 5

Upvotes: 1

Kris
Kris

Reputation: 8868

Problem lies in the call test.functionb('abc'). You are not using object of the class to call the method. So, the self parameter is not passed. Python considers, the first parameter to be self, and you passed 'abc' which is a string.

Use it like test().functionb('abc') , then the default first argument becomes the object of test - like functionb(test_ob, 'abc').

Upvotes: 1

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