SF feature request #686323: Minor array module enhancements
array.extend() now accepts iterable arguments implements as a series
of appends. Besides being a user convenience and matching the behavior
for lists, this the saves memory and cycles that would be used to
create a temporary array object.
diff --git a/Doc/lib/libarray.tex b/Doc/lib/libarray.tex
index 6ec056f..6fd8b0c 100644
--- a/Doc/lib/libarray.tex
+++ b/Doc/lib/libarray.tex
@@ -104,10 +104,13 @@
Return the number of occurences of \var{x} in the array.
\end{methoddesc}
-\begin{methoddesc}[array]{extend}{a}
-Append array items from \var{a} to the end of the array. The two
-arrays must have \emph{exactly} the same type code; if not,
-\exception{TypeError} will be raised.
+\begin{methoddesc}[array]{extend}{iterable}
+Append items from \var{iterable} to the end of the array. If
+\var{iterable} is another array, it must have \emph{exactly} the same
+type code; if not, \exception{TypeError} will be raised. If
+\var{iterable} is not an array, it must be iterable and its
+elements must be the right type to be appended to the array.
+\versionchanged[Formerly, the argument could only be another array]{2.4}
\end{methoddesc}
\begin{methoddesc}[array]{fromfile}{f, n}
diff --git a/Lib/test/test_array.py b/Lib/test/test_array.py
index c9b05c2..0f3e07f 100755
--- a/Lib/test/test_array.py
+++ b/Lib/test/test_array.py
@@ -592,6 +592,13 @@
b = array.array(self.badtypecode())
self.assertRaises(TypeError, a.extend, b)
+ a = array.array(self.typecode, self.example)
+ a.extend(self.example[::-1])
+ self.assertEqual(
+ a,
+ array.array(self.typecode, self.example+self.example[::-1])
+ )
+
def test_coveritertraverse(self):
try:
import gc
diff --git a/Misc/NEWS b/Misc/NEWS
index dfe6e2f..d4aef1e 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -182,7 +182,9 @@
- array objects now support the copy module. Also, their resizing
scheme has been updated the same as for list objects. The improves
- performance for append() operations.
+ the performance (speed and memory usage) of append() operations.
+ Also, array.extend() now accepts any iterable argument for repeated
+ appends without needing to create another temporary array.
- cStringIO.writelines() now accepts any iterable argument and writes
the lines one at a time rather than joining them and writing once.
diff --git a/Modules/arraymodule.c b/Modules/arraymodule.c
index 4c3c726..ed2ea9d 100644
--- a/Modules/arraymodule.c
+++ b/Modules/arraymodule.c
@@ -775,16 +775,35 @@
}
static int
+array_iter_extend(arrayobject *self, PyObject *bb)
+{
+ PyObject *it, *v;
+
+ it = PyObject_GetIter(bb);
+ if (it == NULL)
+ return -1;
+
+ while ((v = PyIter_Next(it)) != NULL) {
+ if (ins1(self, (int) self->ob_size, v) != 0) {
+ Py_DECREF(v);
+ Py_DECREF(it);
+ return -1;
+ }
+ Py_DECREF(v);
+ }
+ Py_DECREF(it);
+ if (PyErr_Occurred())
+ return -1;
+ return 0;
+}
+
+static int
array_do_extend(arrayobject *self, PyObject *bb)
{
int size;
- if (!array_Check(bb)) {
- PyErr_Format(PyExc_TypeError,
- "can only extend array with array (not \"%.200s\")",
- bb->ob_type->tp_name);
- return -1;
- }
+ if (!array_Check(bb))
+ return array_iter_extend(self, bb);
#define b ((arrayobject *)bb)
if (self->ob_descr != b->ob_descr) {
PyErr_SetString(PyExc_TypeError,
@@ -810,6 +829,12 @@
static PyObject *
array_inplace_concat(arrayobject *self, PyObject *bb)
{
+ if (!array_Check(bb)) {
+ PyErr_Format(PyExc_TypeError,
+ "can only extend array with array (not \"%.200s\")",
+ bb->ob_type->tp_name);
+ return NULL;
+ }
if (array_do_extend(self, bb) == -1)
return NULL;
Py_INCREF(self);
@@ -990,9 +1015,9 @@
}
PyDoc_STRVAR(extend_doc,
-"extend(array)\n\
+"extend(array or iterable)\n\
\n\
- Append array items to the end of the array.");
+ Append items to the end of the array.");
static PyObject *
array_insert(arrayobject *self, PyObject *args)
@@ -1881,7 +1906,7 @@
buffer_info() -- return information giving the current memory info\n\
byteswap() -- byteswap all the items of the array\n\
count() -- return number of occurences of an object\n\
-extend() -- extend array by appending array elements\n\
+extend() -- extend array by appending multiple elements from an iterable\n\
fromfile() -- read items from a file object\n\
fromlist() -- append items from the list\n\
fromstring() -- append items from the string\n\
