Using a class method in init

Question

I have the following class, where I want to use the method location_change within __init__for that class. Is there a way to do this? The example I use below is a simplification but what I need to do is use a class method to transform some constructor data. Can this be done in python?

class dummy:

    def __init__(self):

        self.location = 'USA'
        print(self.location)

        location_change()
        print(self.location)

    def location_change():

        self.location = 'UK'


first_dummy = dummy()

There seems to be some confusion between classmethods and methods on classes; sadly, these are different. — Katriel
– Katriel, Commented Jan 17, 2012 at 14:26

dm03514 · Accepted Answer · 2012-01-17 14:26:49Z

5

Sure it can!

self.location_change()

each method in a class should take at least one argument and that is conventionally called self.

def location_change(self):

an introductory tutorial on oop in python http://www.voidspace.org.uk/python/articles/OOP.shtml

the documentation http://docs.python.org/tutorial/classes.html

edited Jan 17, 2012 at 14:26

answered Jan 17, 2012 at 14:16

dm03514

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Comments

S.Lott · Accepted Answer · 2012-01-17 14:34:50Z

3

Try this

class Dummy:

    def __init__(self):

        self.location = 'USA'
        print(self.location)

        self.location_change()
        print(self.location)

    def location_change(self):

        self.location = 'UK'


first_dummy = Dummy()

edited Jan 17, 2012 at 14:34

S.Lott

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answered Jan 17, 2012 at 14:15

Shadow

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Comments

S.Lott · Accepted Answer · 2012-01-17 14:35:10Z

1

class Dummy:

    def __init__(self):

        self.location = 'USA'
        print(self.location)
        Dummy.location_change(self)
        print(self.location)

    def location_change(self):

        self.location = 'UK'


first_dummy = Dummy()
print(first_dummy)

What you needed to do was tell "location_change" that it was working with argument, self. Otherwise it's an undefined variable. You also needed to use the class name when calling it. This should give you:

USA
UK
<__main__.Dummy object at 0x1005ae1d0>

edited Jan 17, 2012 at 14:35

S.Lott

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answered Jan 17, 2012 at 14:19

Bry6n

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1 Comment

Rik Poggi Over a year ago

Why would you call dummy.location_change(self) instead of self.location_change()? This way if a sub-class implement location_change that implementation will not be used!

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