Make starmap() match its pure python definition and accept any itertable input (not...

diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst
index 788d931c2841dd94f2b41fd10c1927dedd207a90..e797aab6ac8a03058c5739859562996f696762bc 100644 (file)
--- a/Doc/library/itertools.rst
+++ b/Doc/library/itertools.rst
@@ -330,17 +330,19 @@ loops that truncate the stream.
 
 .. function:: starmap(function, iterable)
 
-   Make an iterator that computes the function using arguments tuples obtained from
+   Make an iterator that computes the function using arguments obtained from
    the iterable.  Used instead of :func:`imap` when argument parameters are already
    grouped in tuples from a single iterable (the data has been "pre-zipped").  The
    difference between :func:`imap` and :func:`starmap` parallels the distinction
    between ``function(a,b)`` and ``function(*c)``. Equivalent to::
 
       def starmap(function, iterable):
-          iterable = iter(iterable)
-          while True:
-              yield function(*iterable.next())
+          for args in iterable:
+              yield function(*args)
 
+   .. versionchanged:: 2.6
+      Previously, :func:`starmap` required the function arguments to be tuples.
+      Now, any iterable is allowed.
 
 .. function:: takewhile(predicate, iterable)
 

diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py
index 1a3064c3051b259661cb30a6ae0c4cef75df2943..9d1922823d30744bb49932491cc4a45a9ce30ee1 100644 (file)
--- a/Lib/test/test_itertools.py
+++ b/Lib/test/test_itertools.py
@@ -292,7 +292,8 @@ class TestBasicOps(unittest.TestCase):
         self.assertEqual(take(3, starmap(operator.pow, izip(count(), count(1)))),
                          [0**1, 1**2, 2**3])
         self.assertEqual(list(starmap(operator.pow, [])), [])
-        self.assertRaises(TypeError, list, starmap(operator.pow, [[4,5]]))
+        self.assertEqual(list(starmap(operator.pow, [iter([4,5])])), [4**5])
+        self.assertRaises(TypeError, list, starmap(operator.pow, [None]))
         self.assertRaises(TypeError, starmap)
         self.assertRaises(TypeError, starmap, operator.pow, [(4,5)], 'extra')
         self.assertRaises(TypeError, starmap(10, [(4,5)]).next)

diff --git a/Misc/NEWS b/Misc/NEWS
index 9ec0f6ac9fd503150dd8b97559cfe9e11cc8296c..0085416963b5015a1d9245061a24016de950de66 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -993,6 +993,9 @@ Extension Modules
   the context manager protocol.  The _winreg module also gained a new function
   ``ExpandEnvironmentStrings`` to expand REG_EXPAND_SZ keys.
 
+- itertools.starmap() now accepts any iterable input. Previously, it required
+  the function inputs to be tuples.
+
 - Issue #1646: Make socket support TIPC. The socket module now has support
   for TIPC under Linux, see http://tipc.sf.net/ for more information.
 

diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c
index ebb4deb2680ea8d955a1f0625a1faa7c0d3407b1..430313eaa63fd41e6114eaf904d8aaeb88224a32 100644 (file)
--- a/Modules/itertoolsmodule.c
+++ b/Modules/itertoolsmodule.c
@@ -1356,10 +1356,11 @@ starmap_next(starmapobject *lz)
        if (args == NULL)
                return NULL;
        if (!PyTuple_CheckExact(args)) {
+               PyObject *newargs = PySequence_Tuple(args);
                Py_DECREF(args);
-               PyErr_SetString(PyExc_TypeError,
-                               "iterator must return a tuple");
-               return NULL;
+               if (newargs == NULL)
+                       return NULL;
+               args = newargs;
        }
        result = PyObject_Call(lz->func, args, NULL);
        Py_DECREF(args);