How does Python know whether a variable in the class is a method or a variable?

0 votes
print(hasattr(int,         '__call__'))
print(hasattr(lambda x: x, '__call__'))
print('')

class A(object):
    a = int
    b = lambda x : x

print(A.a)
print(A.b)

Gives an output of: 

True
True

<type 'int'>
<unbound method A.<lambda>>

How does Python decide what is going to be a method (as A.b is here) and what is just going to be itself (as A.a is here)?

Sep 18, 2018 in Python by charlie_brown
• 7,710 points
19 views

1 answer to this question.

Your answer

Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.
0 votes

In python objects/variables are wrapped into methods if they are function (i.e type( xxx ) gives FunctionType)

This is because the FunctionType defines a __get__ method, implementing the descriptor protocol, which changes what happens when A.b is looked up. int and most other non-function callables do not define this method:

>>> (lambda x: x).__get__
<method-wrapper '__get__' of function object at 0x0000000003710198>
>>> int.__get__
Traceback (most recent call last):
  File "<pyshell#43>", line 1, in <module>
    int.__get__
AttributeError: type object 'int' has no attribute '__get__'

You could make your own method-wrapper-like behavior by defining some other sort of descriptor. An example of this is the property. property is a type that is not a function, but also defines a __get__ (and __set__) to change what happens when a property is looked up

answered Sep 18, 2018 by ariaholic
• 7,320 points

Related Questions In Python

0 votes
1 answer

How do I use urllib to see if a website is 404 or 200 in Python?

For Python 3, try doing this: import urllib.request, ...READ MORE

answered Nov 29, 2018 in Python by Nymeria
• 3,500 points

edited Dec 11, 2018 by Nymeria 115 views
0 votes
1 answer

How do I check if input string is a valid regular expression or not in Python?

Hi. Good question! Well, just like what ...READ MORE

answered Feb 12 in Python by Nymeria
• 3,500 points
13 views
0 votes
2 answers

what is a class method in python?

Class Method  class method is the method which is ...READ MORE

answered Apr 8 in Python by MrBoot
• 1,210 points
20 views
–1 vote
2 answers

How to find the size of a string in Python?

following way to find length of string  x ...READ MORE

answered Mar 29 in Python by rajesh
• 1,210 points
39 views
0 votes
1 answer

how can i count the items in a list?

suppose you have a list a = [0,1,2,3,4,5,6,7,8,9,10] now ...READ MORE

answered May 2 in Python by Mohammad
• 920 points
18 views
+4 votes
6 answers
0 votes
1 answer

How to get the size of a string in Python?

If you are talking about the length ...READ MORE

answered Jun 4, 2018 in Python by ariaholic
• 7,320 points
46 views
0 votes
1 answer

How can I prevent or alter access to class variables in Python?

The ActiveState solution that Pynt references makes instances of ...READ MORE

answered Dec 5, 2018 in Python by ariaholic
• 7,320 points
38 views

© 2018 Brain4ce Education Solutions Pvt. Ltd. All rights Reserved.
"PMP®","PMI®", "PMI-ACP®" and "PMBOK®" are registered marks of the Project Management Institute, Inc. MongoDB®, Mongo and the leaf logo are the registered trademarks of MongoDB, Inc.