Python object keeping data from previous?

Question

I've seen multiple instances of this question like this one, but it fails to identify what exactly I am doing wrong since I don't have default arguments.

What am I doing wrong? Python object instantiation keeping data from previous instantiation?

#Table.py
class Table:

def __init__(self, players):
    self.deck = Deck()

And this is Main

t = Table(2)
print len(t.deck.cards)

t = Table(2)
print len(t.deck.cards)

I would expect this to print 48 each time, but instead it prints

48 and then 96

Why is this? Shouldn't this member variable be overridden every time?

#Deck.py
from Card import *
import random

class Deck:

suits = ['H','C','D','S']
numbers = [2,3,4,5,6,7,8,9,10,11,12,13,14]
cards = []

def __init__(self):
    for num in self.numbers:
        for suit in self.suits:
            c = Card(num,suit)
            self.cards.append(c);
    random.shuffle(self.cards)

Card.py

class Card:

def __init__(self, num, suit):
    self.num = num
    self.suit = suit

def __repr__(self):
    return str(self.num) + str(self.suit)

def __str__(self):
    return str(self.num) + str(self.suit)

Answer 1

Initialize cards in the constructor, like this:

def __init__(self):
    self.cards = []
    for num in self.numbers:
        for suit in self.suits:
            c = Card(num,suit)
            self.cards.append(c);
    random.shuffle(self.cards)

That way, every time a new instance of the class is created, cards will be freshly initialized.

Your approach didn't work as you wished, since cards is a class data member, shared among all instances of class Deck.

Answer 2

suits, numbers and cards are class variables. So when doing self.cards.append(c) you add to a class variable, which is shared by all instances of all Deck instances.

Put them into __init__ instead:

def __init__(self):

    self.cards = []
    for num in self.numbers:
        for suit in self.suits:
            c = Card(num,suit)
            self.cards.append(c);
    random.shuffle(self.cards)