On Thu, Feb 24, 2011 at 8:27 AM, Jeremy <jlcon...@gmail.com> wrote: > I just discovered the wiki page on sorting > (http://wiki.python.org/moin/HowTo/Sorting/). This describes the new way of > sorting a container instead of using the cmp function. But what do I do for > custom objects? > If I write __lt__, __gt__, etc. functions for my objects, will these be used?
s/functions/methods/ Yes, they will. As Bill Nye would say: "Try It!". The REPL exists for a reason. If you're using Python 2.7+, you may want to use functools.total_ordering() [http://docs.python.org/library/functools.html#functools.total_ordering ] for convenience. > Is this better than defining a key for sorting my custom objects? Unless there are multiple "obvious" ways to sort your objects, yes. Third-party code will be able to sort+compare your objects. Sorting your objects in your own code will be more concise. And you'll be able to use the comparison operators on your objects. Note that, internally, it may be convenient to define the comparison methods in terms of a key comparison. For example: class Person(object): def __init__(self, first, last): self.first_name = first self.last_name = last def _key(self): return (self.last_name, self.first_name) def __lt__(self, other): return self._key() < other._key() # continue defining other comparison methods analogously... Cheers, Chris -- http://mail.python.org/mailman/listinfo/python-list
