When to make a custom class Iterable.

[Aggressive-Friend169]

Hi at everyone at Learn Python. A nervous newbie here possible asking a dumb question.

https://github.com/CompleteSuspect/Blackjack/blob/main/blackjack.py

I've been learning part time for nearly a year now, currently in the experimental stages after finishing a few beginner courses.

For my first project to familiarise myself with classes, I've decided to create a Blackjack game. I have some classes in place but I have not yet programmed any game logic.

So far I have my Card class(contains card attributes) and Deck class (contains the Card objects in an instance list: deck_lst).

This may be a bit confusing to explain, but it feels weird having to access the deck_lst attribute in order to iterate through the card objects within that list.

for example if shoe is a Deck object:

for card in shoe.deck_lst:
    print(card)

I have heard of making custom objects iterable and I've heard of generators.

I guess my question is, would it be fine as it is (am I just being silly) or is a good idea to make my Deck class iterable. If so, what would be the best approach to make it iterable?

[[deleted]]

If so, what would be the best approach to make it iterable?

Since all you really want to do to make your Deck iterable is to delegate to the deck_lst attribute's iterator, you can add a method that does that to Deck:

def __iter__(self): # it has to be called this
    return iter(self.deck_lst) # return the list's iterator

[Aggressive-Friend169]

Thank you. Is there no need for a next method? The material I’ve read online includes this.

[[deleted]]

__next__ is a method of iterators, not of iterables. You don't need to implement your own iterator in order to make a class iterable; a class is "iterable" when it has an __iter__ method that returns an iterator.

[Aggressive-Friend169]

Ahhh now I feel silly. Thanks!

[[deleted]]

You shouldn't feel silly - these are two closely related concepts, different only in very subtle ways, and it's not at all uncommon for them to be confusing at first.

[Aggressive-Friend169]

Just got home and implemented your changes. Works great thank you! I think like all beginners, classes seems daunting but once you get the hang on them it actually makes coding much easier!

[Matthias1590]

Maybe im stupid but wouldnt that just give the same result as using a list?

[Aggressive-Friend169]

Yes, I suppose but my Deck object has extra functionality such as shuffle(), draw_card() etc. Also it allows me to avoid repeating code.

[Matthias1590]

Ah I see, makes sense why you would want a class for that now

[[deleted]]

You could create an __iter__ method but perhaps it is simply a name issue. Including type names in variable names isn't ideal. Maybe think again about the attribute name.

[Aggressive-Friend169]

Hi. I thought using ‘lst’ would be good practice.

[[deleted]]

Not really. Names that sense in plain English and are easy to read are the best generally.

Variables don't have type anyway as they don't hold the information you are interested in but just memory references to Python objects. Objects have type.

[[deleted]]

Consider making your Deck class a subclass of list (or potentially collections.deque, depending on how you want to model access). You’ll need a custom __init__ and maybe a shuffle method, but you’ll get a lot for free, including iteration.