A Universe Set

[Jorgen Grahn]

On Thu, 05 Oct 2006 00:02:51 +0200, Wildemar Wildenburger <wildemar at freakmail.de> wrote:
> Jorgen Grahn wrote:

> Any use cases for these?

>> - the wildcard object, which compares equal to everything else

Like someone else wrote, for quick-and-dirty comparisons or lists and
dictionaries where I don't care about one part. I think I wanted it for
unittest's assertEqual(foo, bar) at one point.

  self.assertEqual(['foo', 42, [], WILDCARD], my_result)

versus

  self.assertEqual('foo', my_result[0])
  self.assertEqual(42, my_result[1])
  self.assertEqual([], my_result[2])
  self.assertEqual(4, len(my_result))
  # possibly assert that 'my_result' is a list-like
  # object too

But I agree that the WILDCARD isn't the kind of object you want to spread
throughout your code; its behaviour is too odd.

>> - infinite xrange()s

Available in itertools, as someone pointed out.

>> - the black hole function 'def f(*args): pass'

I often find myself adding logging to functions by passing sys.stderr.write
as an argument to it.  Passing blackhole is an elegant and fast way of
disabling logging.

>> - the identity function 'def f(x): return x'

I don't think I've used it. Maybe if you do a lot of manipulation of
functions and functors -- in some sense it's to function application what 0
is to addition, or 1 to multiplication.

/Jorgen

-- 
  // Jorgen Grahn <grahn@        Ph'nglui mglw'nafh Cthulhu
\X/     snipabacken.dyndns.org>  R'lyeh wgah'nagl fhtagn!