Modified itertools.izip() to match the behavior of __builtin__.zip()
which can now take zero arguments.
diff --git a/Doc/lib/libitertools.tex b/Doc/lib/libitertools.tex
index b708050..cd7e6de 100644
--- a/Doc/lib/libitertools.tex
+++ b/Doc/lib/libitertools.tex
@@ -226,10 +226,13 @@
\begin{verbatim}
def izip(*iterables):
iterables = map(iter, iterables)
- while True:
+ while iterables:
result = [i.next() for i in iterables]
yield tuple(result)
\end{verbatim}
+
+ \versionchanged[When no iterables are specified, returns a zero length
+ iterator instead of raising a TypeError exception]{2.4}
\end{funcdesc}
\begin{funcdesc}{repeat}{object\optional{, times}}
diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py
index 52ae110..f96ccd5 100644
--- a/Lib/test/test_itertools.py
+++ b/Lib/test/test_itertools.py
@@ -87,7 +87,7 @@
self.assertEqual(list(izip('abcdef', range(3))), zip('abcdef', range(3)))
self.assertEqual(take(3,izip('abcdef', count())), zip('abcdef', range(3)))
self.assertEqual(list(izip('abcdef')), zip('abcdef'))
- self.assertRaises(TypeError, izip)
+ self.assertEqual(list(izip()), zip())
self.assertRaises(TypeError, izip, 3)
self.assertRaises(TypeError, izip, range(3), 3)
# Check tuple re-use (implementation detail)
@@ -199,6 +199,8 @@
self.assertRaises(ValueError, dropwhile(errfunc, [(4,5)]).next)
def test_StopIteration(self):
+ self.assertRaises(StopIteration, izip().next)
+
for f in (chain, cycle, izip):
self.assertRaises(StopIteration, f([]).next)
self.assertRaises(StopIteration, f(StopNow()).next)
@@ -540,6 +542,9 @@
>>> no(lambda x: x%2==0, [1, 2, 5, 9])
False
+>>> quantify(lambda x: x%2==0, xrange(99))
+50
+
>>> list(window('abc'))
[('a', 'b'), ('b', 'c')]
diff --git a/Misc/NEWS b/Misc/NEWS
index 34786bf..410391c 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -23,6 +23,9 @@
Library
-------
+- itertools.izip() with no arguments now returns an empty iterator instead
+ of raising a TypeError exception.
+
- _strptime.py now has a behind-the-scenes caching mechanism for the most
recent TimeRE instance used along with the last five unique directive
patterns. The overall module was also made more thread-safe.
diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c
index e63d02a..4a99fce 100644
--- a/Modules/itertoolsmodule.c
+++ b/Modules/itertoolsmodule.c
@@ -1510,12 +1510,6 @@
PyObject *result;
int tuplesize = PySequence_Length(args);
- if (tuplesize < 1) {
- PyErr_SetString(PyExc_TypeError,
- "izip() requires at least one sequence");
- return NULL;
- }
-
/* args must be a tuple */
assert(PyTuple_Check(args));
@@ -1598,6 +1592,8 @@
PyObject *it;
PyObject *item;
+ if (tuplesize == 0)
+ return NULL;
if (result->ob_refcnt == 1) {
for (i=0 ; i < tuplesize ; i++) {
it = PyTuple_GET_ITEM(lz->ittuple, i);