Python OOP related to usage of instance variables

Question

class idk():
    def __init__(self,name,age):
        self.name = name
        self.age = age
    def t(self):
        self.t = self.name + self.age
    def qrt(self):
        print(len(self.t))                             

abc = idk('abc','19')                 
abc.qrt()

abc.name= 'aduhd'            
abc.qrt()

When i run this code i get the following error

Traceback (most recent call last):
    File "C:/Users/Prajval/Desktop/test.py", line 11, in <module>
        abc.qrt()
    File "C:/Users/Prajval/Desktop/test.py", line 8, in qrt
        print(len(self.t))
TypeError: object of type 'instancemethod' has no len()

what does the following error mean:

TypeError: object of type 'instancemethod' has no len()

It gives the error because variable 't' does not exist

Yorian
– Yorian

2017-09-28 14:44:18 +00:00
Commented Sep 28, 2017 at 14:44 — Yorian
– Yorian, Commented Sep 28, 2017 at 14:44

hspandher · Accepted Answer · 2017-09-28 14:52:08Z

1

You forgot to call the method, which you have given the same name t as an instance variable.

def qrt(self):
    print(len(self.t()))

By naming a method the same as an instance variable you are playing with fire. First time when you call the t method, it would behave as a method, and as a string post first call. Don't dug a hole for yourself to fall in.

edited Sep 28, 2017 at 14:52

answered Sep 28, 2017 at 14:44

hspandher

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Comments

Subham · Accepted Answer · 2021-03-29 13:42:19Z

1

Final code,

class idk():
    def __init__(self,name,age):
        self.name = name
        self.age = age
        
    def t(self):
        self.t1 = self.name + self.age
        return self. t1 # was missing 
        
    def qrt(self):
        print(len(self.t()))                             

abc = idk('abc','19')                 
abc.qrt()

abc.name= 'aduhd'            
abc.qrt()

5
7

[Program finished]

answered Mar 29, 2021 at 13:42

Subham

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