Calling a python method

Question

I have a file notifications.py and comments.py. notifications has a class GetNotifications with a function getNotifs(arg1, arg2). I'd like to call this method in my comments.py, so I do:

from notifications import GetNotifications

Then I create an instance of the class:

getNotifsInstance = GetNotifications()

Then I try to call getNotifs:

notifsDictionary = getNotifsInstance.getNotifs(arg1, arg2)

However, I'm getting the error: TypeError: getNotifs() takes at most 2 arguments (3 given)

Why is it saying I'm giving it 3 arguments when I'm only giving it 2?

When you call a method of an instance it always passes itself as the first parameter. — jamylak
– jamylak, Commented Apr 17, 2012 at 15:08

Marcin · Accepted Answer · 2012-04-17 15:08:23Z

3

You're giving it three arguments: when you call an instance method, the instance is passed as the first parameter. You should add an argument self as the first parameter of the method.

answered Apr 17, 2012 at 15:08

Marcin

50.1k18 gold badges137 silver badges207 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

NPE · Accepted Answer · 2012-04-17 15:19:07Z

3

You've most probably forgotten about the self argument when declaring getNotifs():

def getNotifs(self, arg1, arg2):
   ...

edited Apr 17, 2012 at 15:19

answered Apr 17, 2012 at 15:09

NPE

503k114 gold badges970 silver badges1k bronze badges

Comments

Abhijit · Accepted Answer · 2012-04-17 15:09:14Z

1

Why is it saying I'm giving it 3 arguments when I'm only giving it 2?

Simply because you are accessing the function getNotifys as a member function of object getNotifsInstance. The first argument to any member function is (self) the object reference itself.

answered Apr 17, 2012 at 15:09

Abhijit

64k20 gold badges143 silver badges209 bronze badges

Comments

Tadeck · Accepted Answer · 2012-04-17 15:22:14Z

In the class you can define three kinds of methods:

class A(object):
    def instance_method(*args):
        print '%d arguments given' % len(args)
    @classmethod
    def class_method(*args):
        print '%d arguments given' % len(args)
    @staticmethod
    def static_method(*args):
        print '%d arguments given' % len(args)

And when you invoke them on the instance, you will get additional argument passed to instance method (which will be instance itself) and class method (which will be a class of the instance):

>>> a = A()
>>> a.instance_method('a', 'b')
3 arguments given
>>> a.class_method('a', 'b')
3 arguments given
>>> a.static_method('a', 'b')
2 arguments given

In your case it is probably self (the instance itself), although results would be similar if you would decorate your method with classmethod decorator (in that case you would get a class passed as the first argument).

Collectives™ on Stack Overflow

Calling a python method

4 Answers 4

Comments

Comments

Comments

Comments

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

Comments

Comments

Related