changeset: 89547:2d5544afb510 user: R David Murray date: Sun Mar 09 20:33:35 2014 -0400 files: Doc/whatsnew/3.4.rst description: whatsnew: 'U' mode deprecation (#15204). diff -r 11bc9f669015 -r 2d5544afb510 Doc/whatsnew/3.4.rst --- a/Doc/whatsnew/3.4.rst Sun Mar 09 20:13:16 2014 -0400 +++ b/Doc/whatsnew/3.4.rst Sun Mar 09 20:33:35 2014 -0400 @@ -1948,6 +1948,11 @@ * The :mod:`sysconfig` key ``SO`` is deprecated, it has been replaced by ``EXT_SUFFIX``. +* The ``U`` mode accepted by various ``open`` functions is deprecated. + In Python3 it does not do anything useful, and should be replaced by + appropriate uses of :class:`io.TextIOWrapper` (if needed) and its *newline* + argument. + Deprecations in the C API ------------------------- @@ -2242,7 +2247,14 @@ * Since the *digestmod* argument to the :func:`hmac.new` function will in the future have no default, all calls to :func:`hmac.new` should be changed to - explicitly specify a *digestmod*. (:issue:`17276`). + explicitly specify a *digestmod* (:issue:`17276`). + +* Any calls to ``open`` functions that specify ``U`` should be modified. + ``U`` is ineffective in Python3 and will eventually raise an error if used. + Depending on the function, the equivalent of its old Python2 behavior can be + achieved using either a *newline* argument, or if necessary by wrapping the + stream in :mod:`~io.TextIOWrapper` to use its *newline* argument + (:issue:`15204`). Changes in the C API