Add alternate constructor for itertools.chain().
diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py
index 41e9362..500afef 100644
--- a/Lib/test/test_itertools.py
+++ b/Lib/test/test_itertools.py
@@ -52,6 +52,13 @@
self.assertEqual(take(4, chain('abc', 'def')), list('abcd'))
self.assertRaises(TypeError, list,chain(2, 3))
+ def test_chain_from_iterable(self):
+ self.assertEqual(list(chain.from_iterable(['abc', 'def'])), list('abcdef'))
+ self.assertEqual(list(chain.from_iterable(['abc'])), list('abc'))
+ self.assertEqual(list(chain.from_iterable([''])), [])
+ self.assertEqual(take(4, chain.from_iterable(['abc', 'def'])), list('abcd'))
+ self.assertRaises(TypeError, list, chain.from_iterable([2, 3]))
+
def test_combinations(self):
self.assertRaises(TypeError, combinations, 'abc') # missing r argument
self.assertRaises(TypeError, combinations, 'abc', 2, 1) # too many arguments
diff --git a/Misc/NEWS b/Misc/NEWS
index c28fd85..6df4ebc 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -1247,6 +1247,8 @@
- itertools.starmap() now accepts any iterable input. Previously, it required
the function inputs to be tuples.
+- itertools.chain() now has an alterate constructor, chain.from_iterable().
+
- 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 3b8339c..f29077a 100644
--- a/Modules/itertoolsmodule.c
+++ b/Modules/itertoolsmodule.c
@@ -1638,6 +1638,18 @@
return chain_new_internal(type, source);
}
+static PyObject *
+chain_new_from_iterable(PyTypeObject *type, PyObject *arg)
+{
+ PyObject *source;
+
+ source = PyObject_GetIter(arg);
+ if (source == NULL)
+ return NULL;
+
+ return chain_new_internal(type, source);
+}
+
static void
chain_dealloc(chainobject *lz)
{
@@ -1696,6 +1708,18 @@
first iterable until it is exhausted, then elements from the next\n\
iterable, until all of the iterables are exhausted.");
+PyDoc_STRVAR(chain_from_iterable_doc,
+"chain.from_iterable(iterable) --> chain object\n\
+\n\
+Alternate chain() contructor taking a single iterable argument\n\
+that evaluates lazily.");
+
+static PyMethodDef chain_methods[] = {
+ {"from_iterable", (PyCFunction) chain_new_from_iterable, METH_O | METH_CLASS,
+ chain_from_iterable_doc},
+ {NULL, NULL} /* sentinel */
+};
+
static PyTypeObject chain_type = {
PyVarObject_HEAD_INIT(NULL, 0)
"itertools.chain", /* tp_name */
@@ -1726,7 +1750,7 @@
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)chain_next, /* tp_iternext */
- 0, /* tp_methods */
+ chain_methods, /* tp_methods */
0, /* tp_members */
0, /* tp_getset */
0, /* tp_base */