191 lines
6.0 KiB
ReStructuredText
191 lines
6.0 KiB
ReStructuredText
****************************
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What's New In Python 3.7
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****************************
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:Release: |release|
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:Date: |today|
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.. Rules for maintenance:
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* Anyone can add text to this document. Do not spend very much time
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on the wording of your changes, because your text will probably
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get rewritten to some degree.
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* The maintainer will go through Misc/NEWS periodically and add
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changes; it's therefore more important to add your changes to
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Misc/NEWS than to this file.
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* This is not a complete list of every single change; completeness
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is the purpose of Misc/NEWS. Some changes I consider too small
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or esoteric to include. If such a change is added to the text,
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I'll just remove it. (This is another reason you shouldn't spend
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too much time on writing your addition.)
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* If you want to draw your new text to the attention of the
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maintainer, add 'XXX' to the beginning of the paragraph or
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section.
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* It's OK to just add a fragmentary note about a change. For
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example: "XXX Describe the transmogrify() function added to the
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socket module." The maintainer will research the change and
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write the necessary text.
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* You can comment out your additions if you like, but it's not
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necessary (especially when a final release is some months away).
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* Credit the author of a patch or bugfix. Just the name is
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sufficient; the e-mail address isn't necessary.
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* It's helpful to add the bug/patch number as a comment:
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XXX Describe the transmogrify() function added to the socket
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module.
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(Contributed by P.Y. Developer in :issue:`12345`.)
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This saves the maintainer the effort of going through the Mercurial log
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when researching a change.
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This article explains the new features in Python 3.7, compared to 3.6.
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For full details, see the :ref:`changelog <changelog>`.
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.. note::
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Prerelease users should be aware that this document is currently in draft
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form. It will be updated substantially as Python 3.7 moves towards release,
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so it's worth checking back even after reading earlier versions.
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Summary -- Release highlights
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=============================
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.. This section singles out the most important changes in Python 3.7.
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Brevity is key.
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.. PEP-sized items next.
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New Features
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============
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Other Language Changes
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======================
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* More than 255 arguments can now be passed to a function, and a function can
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now have more than 255 parameters.
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(Contributed by Serhiy Storchaka in :issue:`12844` and :issue:`18896`.)
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* :meth:`bytes.fromhex` and :meth:`bytearray.fromhex` now ignore all ASCII
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whitespace, not only spaces.
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(Contributed by Robert Xiao in :issue:`28927`.)
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New Modules
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===========
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* None yet.
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Improved Modules
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================
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unittest.mock
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-------------
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The :const:`~unittest.mock.sentinel` attributes now preserve their identity
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when they are :mod:`copied <copy>` or :mod:`pickled <pickle>`.
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(Contributed by Serhiy Storchaka in :issue:`20804`.)
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Optimizations
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=============
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* Added two new opcodes: ``LOAD_METHOD`` and ``CALL_METHOD`` to avoid
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instantiation of bound method objects for method calls, which results
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in method calls being faster up to 20%.
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(Contributed by Yury Selivanov and INADA Naoki in :issue:`26110`.)
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Build and C API Changes
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=======================
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* A full copy of libffi is no longer bundled for use when building the
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:mod:`_ctypes <ctypes>` module on non-OSX UNIX platforms. An installed copy
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of libffi is now required when building ``_ctypes`` on such platforms.
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Contributed by Zachary Ware in :issue:`27979`.
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* The fields :c:member:`name` and :c:member:`doc` of structures
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:c:type:`PyMemberDef`, :c:type:`PyGetSetDef`,
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:c:type:`PyStructSequence_Field`, :c:type:`PyStructSequence_Desc`,
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and :c:type:`wrapperbase` are now of type ``const char *`` rather of
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``char *``. (Contributed by Serhiy Storchaka in :issue:`28761`.)
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* The result of :c:func:`PyUnicode_AsUTF8AndSize` and :c:func:`PyUnicode_AsUTF8`
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is now of type ``const char *`` rather of ``char *``.
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(Contributed by Serhiy Storchaka in :issue:`28769`.)
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* Added functions :c:func:`PySlice_Unpack` and :c:func:`PySlice_AdjustIndices`.
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(Contributed by Serhiy Storchaka in :issue:`27867`.)
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Deprecated
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==========
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- Function :c:func:`PySlice_GetIndicesEx` is deprecated and replaced with
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a macro if ``Py_LIMITED_API`` is not set or set to the value between
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``0x03050400`` and ``0x03060000`` (not including) or ``0x03060100`` or
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higher. (Contributed by Serhiy Storchaka in :issue:`27867`.)
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Removed
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=======
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API and Feature Removals
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------------------------
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* Unknown escapes consisting of ``'\'`` and an ASCII letter in replacement
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templates for :func:`re.sub` were deprecated in Python 3.5, and will now
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cause an error.
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* Removed support of the *exclude* argument in :meth:`tarfile.TarFile.add`.
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It was deprecated in Python 2.7 and 3.2. Use the *filter* argument instead.
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* The ``splitunc()`` function in the :mod:`ntpath` module was deprecated in
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Python 3.1, and has now been removed. Use the :func:`~os.path.splitdrive`
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function instead.
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Porting to Python 3.7
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=====================
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This section lists previously described changes and other bugfixes
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that may require changes to your code.
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Changes in the Python API
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-------------------------
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* A format string argument for :meth:`string.Formatter.format`
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is now :ref:`positional-only <positional-only_parameter>`.
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Passing it as a keyword argument was deprecated in Python 3.5.
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(Contributed by Serhiy Storchaka in :issue:`29193`.)
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* Attributes :attr:`~http.cookies.Morsel.key`,
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:attr:`~http.cookies.Morsel.value` and
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:attr:`~http.cookies.Morsel.coded_value` of class
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:class:`http.cookies.Morsel` are now read-only.
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Assigning to them was deprecated in Python 3.5.
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Use the :meth:`~http.cookies.Morsel.set` method for setting them.
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(Contributed by Serhiy Storchaka in :issue:`29192`.)
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CPython bytecode changes
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------------------------
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* Added two new opcodes: :opcode:`LOAD_METHOD` and :opcode:`CALL_METHOD`.
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(Contributed by Yury Selivanov and INADA Naoki in :issue:`26110`.)
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