switch recipe?

[Cliff Wells]

On Fri, 2002-07-12 at 13:05, Mark McEahern wrote:
> > out of curiosity, what happens when n reaches the end of the
> > int/long/whatever that stores it?
> 
> My guess is this will run forever--if you let it.  <wink>
> 
> Perhaps it should allow an optional sentinel?  The assumption is the caller
> is responsible for using it wisely.

Or on your "generic" version (still untested - I just reinstalled my PC
and don't have Python 2.2 yet):

 from __future__ import generators

 def make_switch(*args):
      """Return a generator that loops through args."""
      if not args:
          raise RuntimeError("Missing parameter: args.")
      def switch():
          i = n = 0
          while True:
              i = n % len(args)
              yield args[i]
              n = min(n + 1, len(args))
      return switch

or possibly:

 def make_switch(*args):
      """Return a generator that loops through args."""
      if not args:
          raise RuntimeError("Missing parameter: args.")
      def switch():
          while True:
              for a in args:
                 yield a
      return switch