On Wed, Aug 4, 2010 at 4:17 PM, Alex Hall <mehg...@gmail.com> wrote: > Hi all, > Further to my questions about overriding builtin methods earlier, how > would I make a class able to be accessed and changed using index > notation? For example, take the following: > deck=CardPile(52) #creates a new deck of cards > print(len(deck)) #prints 52, thanks to my __len__ function > for c in deck: print c #also works thanks to __iter__ > print(deck[4]) #fails with a list index out of range error > How would I get the last one working? I tried __getattr__(self, i), > but it did not work. I want to be able to get an arbitrary item from > the "pile" of cards (which can be a deck, a hand, whatever), and/or > set an element. A "pile" is just a list of Card objects, so I would > only need to use sequence indexing, not mapping functions. >
Implement __getitem__(self, key) (See http://docs.python.org/reference/datamodel.html#emulating-container-types ) If you want to support slicing (access like deck[0:10]), you'll need to handle getting a slice object as the key in addition to accepting an integer key. If a pile is really "just" a list of cards, you may want to look into inheriting from list instead of re-implementing all of the functionality on your own. -- Jerry
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