In [3]:

    

class Foo:
    def __getitem__(self, pos):
        return range(0, 30, 10)[pos]


    

In [4]:

    

f = Foo()
f[1]


    

    
Out[4]:





10

In [5]:

    

for i in f: print(i)


    

    




0
10
20

In [6]:

    

20 in f


    

    
Out[6]:





True

In [7]:

    

15 in f


    

    
Out[7]:





False

In [9]:

    

from random import shuffle
l = list(range(10))
shuffle(l)
l


    

    
Out[9]:





[5, 3, 7, 6, 9, 8, 4, 0, 1, 2]

In [10]:

    

import collections

Card = collections.namedtuple('Card', ['rank', 'suit'])

class FrenchDeck:
    ranks = [str(n) for n in range(2, 11)] + list('JQKA')
    suits = 'spades diamonds clubs hearts'.split()
    
    def __init__(self):
        self._cards = [Card(rank, suit) for suit in self.suits
                                        for rank in self.ranks]
        
    def __len__(self):
        return len(self._cards)
    
    def __getitem__(self, position):
        return self._cards[position]


    

In [13]:

    

deck = FrenchDeck()
shuffle(deck)


    

    




---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-13-073dfb875881> in <module>()
      1 deck = FrenchDeck()
----> 2 shuffle(deck)

c:\users\langestrst01\appdata\local\continuum\anaconda3\envs\fluentpy\lib\random.py in shuffle(self, x, random)
    270                 # pick an element in x[:i+1] with which to exchange x[i]
    271                 j = randbelow(i+1)
--> 272                 x[i], x[j] = x[j], x[i]
    273         else:
    274             _int = int

TypeError: 'FrenchDeck' object does not support item assignment

In [14]:

    

def set_card(deck, position, card):
    deck._cards[position] = card


    

In [15]:

    

FrenchDeck.__setitem__ = set_card


    

In [16]:

    

shuffle(deck)


    

In [18]:

    

print(deck[:5])


    

    




[Card(rank='Q', suit='clubs'), Card(rank='A', suit='hearts'), Card(rank='3', suit='diamonds'), Card(rank='J', suit='diamonds'), Card(rank='7', suit='hearts')]

In [19]:

    

class Struggle:
    def __len__(self): return 23
    
from collections import abc
isinstance(Struggle(), abc.Sized)


    

    
Out[19]:





True

In [ ]:

    

try:
    field_names = field_names.replace(',',' ').split()
except AttributeError:
    pass
field_names = tuple(field_names)


    

In [21]:

    

import collections

Card = collections.namedtuple('Card', ['rank', 'suit'])

class FrenchDeck2(collections.MutableSequence):
    ranks = [str(n) for n in range(2, 11)] + list('JQKA')
    suits = 'spades diamonds clubs hearts'.split()
    
    def __init__(self):
        self._cards = [Card(rank, suit) for suit in self.suits
                                        for rank in self.ranks]
        
    def __len__(self):
        return len(self._cards)
    
    def __getitem__(self, position):
        return self._cards[position]
    
    def __setitem__(self, position, value):
        self._cards[position] = value
        
    def __delitem__(self, position):
        del self._cards[position]
        
    def insert(self, position, value):
        self._cards.insert(position, value)


    

In [1]:

    

import abc


    

In [3]:

    

import abc

class Tombola(abc.ABC):
    
    @abc.abstractmethod
    def load(self, iterable):
        """Add items from an iterable"""
        
    @abc.abstractmethod
    def pick(self):
        """Remove item at random, returning it
        
        This method should raise 'LookupError' when the instance is empty.
        """
        
    def loaded(self):
        """Return 'True' if there's at least 1 item, 'False' otherwise."""
        return bool(self.inspect())
    
    def inspect(self):
        """Return a sorted tuple with the items currently inside."""
        items = []
        while True:
            try:
                items.append(self.pick())
            except LookupError:
                break
        self.load(items)
        return tuple(sorted(items))


    

In [4]:

    

class Fake(Tombola):
    def pick(self):
        return 13


    

In [7]:

    

Fake


    

    
Out[7]:





__main__.Fake

In [8]:

    

f = Fake()


    

    




---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-8-eb09ed8f651b> in <module>()
----> 1 f = Fake()

TypeError: Can't instantiate abstract class Fake with abstract methods load

In [12]:

    

import random

class BingoCage(Tombola):
    
    def __init__(self, items):
        self._randomizer = random.SystemRandom()
        self._items = []
        self.load(items)
        
    def load(self, items):
        self._items.extend(items)
        self._randomizer.shuffle(self._items)
        
    def pick(self):
        try:
            return self._items.pop()
        except IndexError:
            raise LookupError('pick from empty BingoCage')
            
    def __call__(self):
        self.pick()


    

In [13]:

    

import random

class LotteryBlower(Tombola):
    
    def __init__(self, iterable):
        self._balls = list(iterable)
        
    def load(self, iterable):
        self._balls.extend(iterable)
        
    def pick(self):
        try:
            position = random.randrange(len(self._balls))
        except ValueError:
            raise LookupError('pick from empty LotteryBlower')
        return self._balls.pop(position)
    
    def loaded(self):
        return bool(self._balls)
    
    def inspect(self):
        return tuple(sorted(self._balls))


    

In [14]:

    

from random import randrange

@Tombola.register
class TomboList(list):
    
    def pick(self):
        if self:
            position = randrange(len(self))
            return self.pop(position)
        else:
            raise LookupError('pop from empty TomboList')
            
    load = list.extend
    
    def loaded(self):
        return bool(self)
    
    def inspect(self):
        return tuple(sorted(self))


    

In [ ]: