difference between class and instance attributes

0 votes

what is the difference between the following codes?

1. class A(object):
    foo = 3   #set default value
2. class B(object):
    def __init__(self, foo=3):
        self.foo = foo
How will it affect the performance or space requirements while creating a lot of instances?
Sep 17, 2018 in Python by ana1504.k
• 7,910 points
844 views

2 answers to this question.

0 votes

In Python, there is no need to compare to True or False. In the following code, the opposite of dest in smaller.keys() is (dest not in smaller.keys())

So it must be written as:

if(dest not in smaller.keys()):

answered Sep 17, 2018 by SDeb
• 13,300 points
0 votes

Apart from the performance, there is a significant semantic difference between the two codes. only one object is referred to in case of class attribute whereas there can be multiple objects referred to in case of instance-attribute-set-at-instantiation.

For example :

1.   class A: foo = [] 

     a, b = A(), A() 

     a.foo.append(3) 

      b.foo

2.  class A: 

     def __init__(self): self.foo = [] 

     a, b = A(), A() a.foo.append(3) 

      b.foo

answered Sep 17, 2018 by SDeb
• 13,300 points

Related Questions In Python

0 votes
1 answer

What is the difference between an interface and abstract class?

Interfaces An interface is a contract: The person writing ...READ MORE

answered Nov 30, 2020 in Python by Gitika
• 65,890 points
746 views
0 votes
1 answer

What's the difference in Qt between setVisible, setShown and show/hide

show() is just a convenience function for ...READ MORE

answered Apr 17, 2018 in Python by anonymous
7,883 views
0 votes
1 answer

What is the difference between list and tuple?

Lists are mutable(values can be changed) whereas ...READ MORE

answered May 5, 2018 in Python by aayushi
• 750 points
6,926 views
0 votes
1 answer

Difference between '==' and 'is'

'==' checks for the equality of the ...READ MORE

answered May 14, 2018 in Python by Nietzsche's daemon
• 4,260 points
750 views
0 votes
2 answers
+1 vote
2 answers

how can i count the items in a list?

Syntax :            list. count(value) Code: colors = ['red', 'green', ...READ MORE

answered Jul 7, 2019 in Python by Neha
• 330 points

edited Jul 8, 2019 by Kalgi 4,359 views
0 votes
1 answer
0 votes
1 answer

Difference between module and Package in Python

A module is basically a single file ...READ MORE

answered Nov 13, 2018 in Python by SDeb
• 13,300 points
2,354 views
0 votes
1 answer

difference between "*" and "**"

The "**" operator is used for 'power ...READ MORE

answered Nov 19, 2018 in Python by SDeb
• 13,300 points
3,609 views
webinar REGISTER FOR FREE WEBINAR X
REGISTER NOW
webinar_success Thank you for registering Join Edureka Meetup community for 100+ Free Webinars each month JOIN MEETUP GROUP