From: Raymond Hettinger <python@rcn.com>
Date: Thu, 11 Mar 2004 07:34:19 +0000 (+0000)
Subject: list_inplace_concat() is now expressed in terms of list_extend() which
X-Git-Tag: v2.4a1~720
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=97bc6182297ab383d54dca4b85fe656a658e7f0d;p=python

list_inplace_concat() is now expressed in terms of list_extend() which
avoids creating an intermediate tuple for iterable arguments other than
lists or tuples.

In other words, a+=b no longer requires extra memory when b is not a
list or tuple.  The list and tuple cases are unchanged.
---

diff --git a/Objects/listobject.c b/Objects/listobject.c
index b61d7da0ad..6bb6d8c797 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -707,20 +707,6 @@ listextend_internal(PyListObject *self, PyObject *b)
 	return 0;
 }
 
-static PyObject *
-list_inplace_concat(PyListObject *self, PyObject *other)
-{
-	other = PySequence_Fast(other, "argument to += must be iterable");
-	if (!other)
-		return NULL;
-
-	if (listextend_internal(self, other) < 0)
-		return NULL;
-
-	Py_INCREF(self);
-	return (PyObject *)self;
-}
-
 static PyObject *
 listextend(PyListObject *self, PyObject *b)
 {
@@ -790,6 +776,19 @@ listextend(PyListObject *self, PyObject *b)
 	return NULL;
 }
 
+static PyObject *
+list_inplace_concat(PyListObject *self, PyObject *other)
+{
+	PyObject *result;
+
+	result = listextend(self, other);
+	if (result == NULL)
+		return result;
+	Py_DECREF(result);
+	Py_INCREF(self);
+	return (PyObject *)self;
+}
+
 static PyObject *
 listpop(PyListObject *self, PyObject *args)
 {