diff options
Diffstat (limited to 'Doc/whatsnew/3.7.rst')
| -rw-r--r-- | Doc/whatsnew/3.7.rst | 31 |
1 files changed, 25 insertions, 6 deletions
diff --git a/Doc/whatsnew/3.7.rst b/Doc/whatsnew/3.7.rst index 8a3afdf..762d84a 100644 --- a/Doc/whatsnew/3.7.rst +++ b/Doc/whatsnew/3.7.rst @@ -97,9 +97,10 @@ Significant improvements in the standard library: CPython implementation improvements: +* Avoiding the use of ASCII as a default text encoding: + * :ref:`PEP 538 <whatsnew37-pep538>`, legacy C locale coercion + * :ref:`PEP 540 <whatsnew37-pep540>`, forced UTF-8 runtime mode * :ref:`PEP 552 <whatsnew37-pep552>`, deterministic .pycs -* :ref:`PEP 538 <whatsnew37-pep538>`, legacy C locale coercion -* :ref:`PEP 540 <whatsnew37-pep540>`, forced UTF-8 runtime mode * :ref:`the new development runtime mode <whatsnew37-devmode>` * :ref:`PEP 565 <whatsnew37-pep565>`, improved :exc:`DeprecationWarning` handling @@ -184,7 +185,8 @@ PEP 538: Legacy C Locale Coercion An ongoing challenge within the Python 3 series has been determining a sensible default strategy for handling the "7-bit ASCII" text encoding assumption -currently implied by the use of the default C locale on non-Windows platforms. +currently implied by the use of the default C or POSIX locale on non-Windows +platforms. :pep:`538` updates the default interpreter command line interface to automatically coerce that locale to an available UTF-8 based locale as @@ -205,10 +207,18 @@ continues to be ``backslashreplace``, regardless of locale. Locale coercion is silent by default, but to assist in debugging potentially locale related integration problems, explicit warnings (emitted directly on -:data:`~sys.stderr` can be requested by setting ``PYTHONCOERCECLOCALE=warn``. +:data:`~sys.stderr`) can be requested by setting ``PYTHONCOERCECLOCALE=warn``. This setting will also cause the Python runtime to emit a warning if the legacy C locale remains active when the core interpreter is initialized. +While :pep:`538`'s locale coercion has the benefit of also affecting extension +modules (such as GNU ``readline``), as well as child processes (including those +running non-Python applications and older versions of Python), it has the +downside of requiring that a suitable target locale be present on the running +system. To better handle the case where no suitable target locale is available +(as occurs on RHEL/CentOS 7, for example), Python 3.7 also implements +:ref:`whatsnew37-pep540`. + .. seealso:: :pep:`538` -- Coercing the legacy C locale to a UTF-8 based locale @@ -231,8 +241,17 @@ The forced UTF-8 mode can be used to change the text handling behavior in an embedded Python interpreter without changing the locale settings of an embedding application. -The UTF-8 mode is enabled by default when the locale is "C". See -:ref:`whatsnew37-pep538` for details. +While :pep:`540`'s UTF-8 mode has the benefit of working regardless of which +locales are available on the running system, it has the downside of having no +effect on extension modules (such as GNU ``readline``), child processes running +non-Python applications, and child processes running older versions of Python. +To reduce the risk of corrupting text data when communicating with such +components, Python 3.7 also implements :ref:`whatsnew37-pep540`). + +The UTF-8 mode is enabled by default when the locale is ``C`` or ``POSIX``, and +the :pep:`538` locale coercion feature fails to change it to a UTF-8 based +alternative (whether that failure is due to ``PYTHONCOERCECLOCALE=0`` being set, +``LC_ALL`` being set, or the lack of a suitable target locale). .. seealso:: |