[docs] A bug in Python v2.6.6 documentation

April 1, 2011


      Hello,
I have found a bug in the chapter 9.7.1. Itertool functions:
product(A, B) is not equivalent to ((x,y) for x in A for y in B)

It is untrue for dependent iterators - and here is the proof:
...
...
...
class c:
...     def g(self):
...         for i in xrange(self.x):
...             yield i
...     def h(self, x):
...         for i in xrange(x):
...             self.x = i
...             yield i
for i in ((x, y) for x in d.h(4) for y in d.g()):
...     print i
(1, 0)
(2, 0)
(2, 1)
(3, 0)
(3, 1)
(3, 2)
for i in product(d.h(4), d.g()):
... print i
(0, 0)
(0, 1)
(0, 2)
(1, 0)
(1, 1)
(1, 2)
(2, 0)
(2, 1)
(2, 2)
(3, 0)
(3, 1)
(3, 2)
Greetings, J.Kowalski

[docs] A bug in Python v2.6.6 documentation

Jakub Kowalski