How to set class attributes with __init__ method?

Question

I don't get how to access class attributes within class methods. When I assign to variables using self.something within a method, it does not access the class attributes.

class Dictionary(object):

    words = []

    def __init(self):
        self.words_file = open('words.txt')
        self.words = [x.strip('\n') for x in words_text.readlines()]
        words_file.close()

    def print_list(self):
        print self.words

d = Dictionary()
d.print_list()

What I get as out put is [] .

I tried not using the words = [] at the first, then it gives the following error:

AttributeError: 'Dictionary' object has no attribute 'words'

Answer 1

The method name should be __init__ , with two underscores at the end, not __init :

def __init__(self): #here!
   self.words_file = open('words.txt')
   self.words = [x.strip('\n') for x in words_text.readlines()]
   words_file.close()

Answer 2

This seems to be closer to your intention:

class Dictionary(object):

    def __init__(self):
        with open('words.txt') as words_file:
            self.words = [x.strip('\n') for x in words_file]

    def print_list(self):
        print self.words

d = Dictionary()
d.print_list()

You have to be careful with your naming of special methods. They always have to start and end with two underscores. So, it has to be __init__ . If you use a different name, Python will use the default __init__() of object . Of course, this does not set words as an instance attribute.

This:

class Dictionary(object):

    words = []

creates a new class attribute. It is shared among all instances. Accessing words on self :

self.words

looks in the instance first. If it cannot find the attribute word there, it goes to the class. Therefore, you got an empty list for this case.