使用__str__打印对象的数组元素

Question

I am doing a mini project in Coursera. ( Card is another class which has been declared elsewhere.)

class Deck:    
    def __init__(self):
        self.deck = []
        for i in SUITS:
            for j in RANKS:
                self.deck.append(Card(str(i), str(j)))
    def deal_card(self):
        self.temp = random.randrange(0,52)        
        return(self.deck[self.temp])

    def __str__(self):
        #TODO

main()
test_deck = Deck()
c1 = test_deck.deal_card()
print test_deck

I understand that the list self.deck contains a list of Card objects, Can anyone tell me how to print the value of self.deck (which this object is referring to) in my __str__ method?

Answer 1

只需将其转换为字符串即可。

return str(self.deck)

Answer 2

You can also do like this:

def __str__(self):
  return ','.join(str(x) for x in self.deck)

After, each of the Card instances of the deck must have their own str method overridden so that it formats properly too.

Answer 3

Python's Docs should tell you how to use __str__ .

Basically when you do:

print something

Python calls the __str__ method of something and writes that to the output.

Based on my guess, you would probably want to print fact that this object is a deck. So something like this might be what you want:

class Deck:
    # ...
    def __str__(self):
        return "Deck()"

---

Since you are learning Python, I have a bunch of suggestions:

1. As @abarnert said, when you do class ABC: in Python 2, it is an old-style class. (More here )
2. Although not necessary, you should have a empty lines before every function.
3. Avoid using single-character variable names. (like i and j )

So, your code (should) look like:

class Deck(object):

    def __init__(self):  # Blank line above...
        self.deck = []
        # Change variable names...
        for suit in SUITS:
            for rank in RANKS:
                self.deck.append(Card(str(suit), str(rank)))

    def deal_card(self):  # Blank line above...
        self.temp = random.randrange(0,52)
        return(self.deck[self.temp])

    def __str__(self):
        return "Deck()"

And lastly, you might want to read this , which turns out to be the same page as the one I linked before, twice.