[Python-checkins] CVS: python/dist/src/Lib/test test_generators.py,1.4,1.5

[Tim Peters]

Update of /cvsroot/python/python/dist/src/Lib/test
In directory usw-pr-cvs1:/tmp/cvs-serv21852/python/dist/src/Lib/test

Modified Files:
	test_generators.py 
Log Message:
Another variant of the 2-3-5 test, mixing generators with a LazyList class.
Good news:  Some of this stuff is pretty sophisticated (read nuts), and
I haven't bumped into a bug yet.
Bad news:  If I run the doctest in an infinite loop, memory is clearly
leaking.


Index: test_generators.py
===================================================================
RCS file: /cvsroot/python/python/dist/src/Lib/test/test_generators.py,v
retrieving revision 1.4
retrieving revision 1.5
diff -C2 -r1.4 -r1.5
*** test_generators.py	2001/06/24 03:44:52	1.4
--- test_generators.py	2001/06/24 05:47:06	1.5
***************
*** 406,410 ****
--- 406,447 ----
  [200, 216, 225, 240, 243, 250, 256, 270, 288, 300, 320, 324, 360, 375, 384]
  [400, 405, 432, 450, 480, 486, 500, 512, 540, 576, 600, 625, 640, 648, 675]
+ 
+ Heh.  Here's one way to get a shared list, complete with an excruciating
+ namespace renaming trick.  The *pretty* part is that the times() and merge()
+ functions can be reused as-is, because they only assume their stream
+ arguments are iterable -- a LazyList is the same as a generator to times().
+ 
+ >>> class LazyList:
+ ...     def __init__(self, g):
+ ...         self.sofar = []
+ ...         self.fetch = g.next
+ ...
+ ...     def __getitem__(self, i):
+ ...         sofar, fetch = self.sofar, self.fetch
+ ...         while i >= len(sofar):
+ ...             sofar.append(fetch())
+ ...         return sofar[i]
+ 
+ >>> def m235():
+ ...     yield 1
+ ...     # Gack:  m235  below actually refers to a LazyList.
+ ...     me_times2 = times(2, m235)
+ ...     me_times3 = times(3, m235)
+ ...     me_times5 = times(5, m235)
+ ...     for i in merge(merge(me_times2,
+ ...                          me_times3),
+ ...                    me_times5):
+ ...         yield i
+ 
+ >>> m235 = LazyList(m235())
+ >>> for i in range(5):
+ ...     print [m235[j] for j in range(15*i, 15*(i+1))]
+ [1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 16, 18, 20, 24]
+ [25, 27, 30, 32, 36, 40, 45, 48, 50, 54, 60, 64, 72, 75, 80]
+ [81, 90, 96, 100, 108, 120, 125, 128, 135, 144, 150, 160, 162, 180, 192]
+ [200, 216, 225, 240, 243, 250, 256, 270, 288, 300, 320, 324, 360, 375, 384]
+ [400, 405, 432, 450, 480, 486, 500, 512, 540, 576, 600, 625, 640, 648, 675]
  """
+ 
  
  __test__ = {"tut": tutorial_tests,