Patrick Maupin wrote: > Duncan Booth wrote: > >> I prefer writing an 'if' statement here, Bryan prefers 'get', that's >> just a choice of style. But 'setdefault' here, that has no style. > > Well, I'm often told I have no style, and I _did_ admit that it's an > abuse of setdefault. However, I often use setdefault to populate > nested dictionaries, or dictionaries of sets or lists, e.g.: > > for x, y in somebiglist: > bigdict.setdefault(x,set()).add(y) # Strips duplicates > > > for x, y in somebiglist: > bigdict.setdefault(x,[]).append(y) # Preserves duplicates > > To my mind, this latter is so much cleaner and clearer than any of the > alternatives that it just isn't funny:
Yes, but storing a mutable is a not unreasonable use of setdefault. What I objected to was storing an immutable just to overwrite it immediately. Also, while I agree it is shorter, I'm not convinced that it is much cleaner, and it is likely to be slower if there are a lot of duplicates, possibly a lot slower if the mutable object has much overhead on its construction. -- http://mail.python.org/mailman/listinfo/python-list
