# HG changeset patch
# Parent  4a55b98314cd690ee7526cc5fd5d9cc1fec40972
Issue #23231: Document codecs.iterencode(), iterdecode() shortcomings

diff -r 4a55b98314cd Doc/library/codecs.rst
--- a/Doc/library/codecs.rst	Mon Jan 12 21:03:41 2015 +0100
+++ b/Doc/library/codecs.rst	Sat Aug 20 09:21:11 2016 +0000
@@ -221,6 +221,10 @@
    The *errors* argument (as well as any
    other keyword argument) is passed through to the incremental encoder.
 
+   This function requires that the codec accept text :class:`str` objects
+   to encode. Therefore it does not support bytes-to-bytes encoders such as
+   ``base64_codec``.
+
 
 .. function:: iterdecode(iterator, encoding, errors='strict', **kwargs)
 
@@ -229,6 +233,11 @@
    The *errors* argument (as well as any
    other keyword argument) is passed through to the incremental decoder.
 
+   This function requires that the codec accept :class:`bytes` objects
+   to decode. Therefore it does not support text-to-text encoders such as
+   ``rot_13``, although ``rot_13`` may be used equivalently with
+   :func:`iterencode`.
+
 
 The module also provides the following constants which are useful for reading
 and writing to platform dependent files: