CODEWITHSUNDEEP
pythonpython-3.x
Introzoid
Introzoid

Reputation: 15

self variable changed in class not returning

I tried to use len(self.inbox) before to return how many elements are in the list that holds the tuples, however, I couldn't get that to work, so I'm trying to make it so when a new element is added to inbox list, it will add one to x which will basically take the role of len().

class inbox:
    """Inbox class:
       add_new_arrival, message_count, get_unread_indexes, get_message, delete, clear"""
    def __init__(self):
        self.inbox = []
        self.x = 0

    def add_new_arrival(self, from_number, time_arrived, text_of_SMS):
        # Makes new SMS tuple, inserts it after other messages in the store.
        # When creating this message, its has_been_viewed status is set to False.
        self.x += 1
        self.inbox.append(tuple([from_number, time_arrived, text_of_SMS, False]))

    def message_count(self):
        # Returns the number of sms messages in inbox
        return self.x

inbox().add_new_arrival("from number", "time arrived", "text")
print(inbox().message_count())

However, when I run the program, the print at the end will return 0, even though I add a new message with inbox().add_new_arrival(...).

It should return 1 but it doesn't, and I'm not understanding.

Upvotes: 0

Views: 43

Answers (2)

Håken Lid
Håken Lid

Reputation: 23064

Since your inbox class is basically a wrapper around a list, you could make it a subclass of UserList and have access to all list methods.

from collections import UserList

class Inbox(UserList):
    """
    Inbox class: add_new_arrival, message_count, 
    get_unread_indexes, get_message, delete, clear
    """

    def add_new_arrival(self, from_number, time_arrived, text_of_SMS):
        """Makes new SMS tuple, inserts it after other messages in the store.
        When creating this message, its has_been_viewed status is set to False"""
        self.append((from_number, time_arrived, text_of_SMS, False))

my_inbox = Inbox()
my_inbox.add_new_arrival("from number", "time arrived", "text")
print(len(my_inbox))

Upvotes: 0

Wes Doyle
Wes Doyle

Reputation: 2287

You are running message_count() on a new instance of your inbox class (inbox()), which is instantiated with an inbox of length zero.

You might consider assigning an instance of your inbox class to a variable, using that object as you need.:

class inbox:
    """
    Inbox class: add_new_arrival, message_count, 
    get_unread_indexes, get_message, delete, clear
    """
    def __init__(self):
        self.inbox = []

    def add_new_arrival(self, from_number, time_arrived, text_of_SMS):
        # Makes new SMS tuple, inserts it after other messages in the store.
        # When creating this message, its has_been_viewed status is set to False.
        self.inbox.append(tuple([from_number, time_arrived, text_of_SMS, False]))

    def message_count(self):
        # Returns the number of sms messages in inbox
        return len(self.inbox)

my_inbox = inbox()
my_inbox.add_new_arrival("from number", "time arrived", "text")
print(my_inbox.message_count())

Upvotes: 1

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