diff options
Diffstat (limited to 'Lib')
| -rw-r--r-- | Lib/struct.py | 12 | ||||
| -rw-r--r-- | Lib/test/test_struct.py | 22 |
2 files changed, 34 insertions, 0 deletions
diff --git a/Lib/struct.py b/Lib/struct.py index b4f56bb..51ee29a 100644 --- a/Lib/struct.py +++ b/Lib/struct.py @@ -62,6 +62,18 @@ def pack(fmt, *args): o = _compile(fmt) return o.pack(*args) +def pack_to(fmt, buf, offset, *args): + """ + Pack the values v2, v2, ... according to fmt, write + the packed bytes into the writable buffer buf starting at offset. + See struct.__doc__ for more on format strings. + """ + try: + o = _cache[fmt] + except KeyError: + o = _compile(fmt) + return o.pack_to(buf, offset, *args) + def unpack(fmt, s): """ Unpack the string, containing packed C structure data, according diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py index 6bc1f86..7981a52 100644 --- a/Lib/test/test_struct.py +++ b/Lib/test/test_struct.py @@ -509,6 +509,28 @@ class PackBufferTestCase(unittest.TestCase): self.assertRaises(struct.error, s.pack_to, small_buf, 0, test_string) self.assertRaises(struct.error, s.pack_to, small_buf, 2, test_string) + def test_pack_to_fn( self ): + test_string = 'Reykjavik rocks, eow!' + writable_buf = array.array('c', ' '*100) + fmt = '21s' + pack_to = lambda *args: struct.pack_to(fmt, *args) + + # Test without offset + pack_to(writable_buf, 0, test_string) + from_buf = writable_buf.tostring()[:len(test_string)] + self.assertEquals(from_buf, test_string) + + # Test with offset. + pack_to(writable_buf, 10, test_string) + from_buf = writable_buf.tostring()[:len(test_string)+10] + self.assertEquals(from_buf, (test_string[:10] + test_string)) + + # Go beyond boundaries. + small_buf = array.array('c', ' '*10) + self.assertRaises(struct.error, pack_to, small_buf, 0, test_string) + self.assertRaises(struct.error, pack_to, small_buf, 2, test_string) + + def test_main(): test.test_support.run_unittest(PackBufferTestCase) |