Assorted 3.4 What's New updates
- cross-references and attributions for inspect changes - note improvements to inspect and pydoc handling of metaclasses and dynamic attributes (courtesy of the enum PEP) - group all CPython implementation specific changes into a common section - add see also links for most of the PEPs - fix the see also link for the release PEP - add suitable caveats on Argument Clinic inclusion - clarify the change to __wrapped__ handling
This commit is contained in:
Nick Coghlan
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862542e500
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@ -1009,6 +1009,8 @@ updated as expected:
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.. versionadded:: 3.3
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.. _inspect-module-cli:
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Command Line Interface
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----------------------
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@ -75,7 +75,7 @@ For full details, see the
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.. seealso::
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.. :pep:`4XX` - Python 3.4 Release Schedule
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:pep:`429` - Python 3.4 Release Schedule
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Summary -- Release highlights
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@ -96,32 +96,30 @@ New library modules:
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:mod:`select` module primitives.
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* :mod:`statistics`: A basic numerically stable statistics library (:pep:`450`).
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New built-in features:
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New expected features for Python implementations:
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* :ref:`PEP 442: Safe object finalization <pep-442>`.
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* :ref:`PEP 445: Configurable memory allocators <pep-445>`.
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* :ref:`PEP 446: Make newly created file descriptors non-inheritable <pep-446>`.
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Implementation improvements:
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* A more efficient :mod:`marshal` format (:issue:`16475`).
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* Improve finalization of Python modules to avoid setting their globals
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to None, in most cases (:issue:`18214`).
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* "Argument Clinic", providing improved introspection support for builtin
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and standard library extension types implemented in C (:pep:`436`)
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* command line option for :ref:`isolated mode <using-on-misc-options>`,
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(:issue:`16499`).
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Significantly Improved Library Modules:
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* Single-dispatch generic functions (:pep:`443`)
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* Single-dispatch generic functions in :mod:`functoools` (:pep:`443`)
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* SHA-3 (Keccak) support for :mod:`hashlib`.
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* TLSv1.1 and TLSv1.2 support for :mod:`ssl`.
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* :mod:`multiprocessing` now has option to avoid using :func:`os.fork`
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on Unix (:issue:`8713`).
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Security improvements:
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CPython implementation improvements:
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* command line option for :ref:`isolated mode <using-on-misc-options>`,
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:issue:`16499`.
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* :ref:`PEP 442: Safe object finalization <pep-442>`
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* :ref:`PEP 445: Configurable memory allocators <pep-445>`
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* Improve finalization of Python modules to avoid setting their globals
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to None, in most cases (:issue:`18214`).
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* A more efficient :mod:`marshal` format (:issue:`16475`).
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* "Argument Clinic", an initial step towards providing improved introspection
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support for builtin and standard library extension types implemented in C
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(:pep:`436`)
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Please read on for a comprehensive list of user-facing changes.
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@ -130,41 +128,17 @@ Please read on for a comprehensive list of user-facing changes.
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PEP 446: Make newly created file descriptors non-inheritable
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============================================================
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The :pep:`446` makes newly created file descriptors :ref:`non-inheritable
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:pep:`446` makes newly created file descriptors :ref:`non-inheritable
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<fd_inheritance>`. New functions and methods:
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* :func:`os.get_inheritable`, :func:`os.set_inheritable`
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* :func:`os.get_handle_inheritable`, :func:`os.set_handle_inheritable`
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* :meth:`socket.socket.get_inheritable`, :meth:`socket.socket.set_inheritable`
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.. _pep-445:
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PEP 445: Add new APIs to customize Python memory allocators
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===========================================================
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The :pep:`445` adds new Application Programming Interfaces (API) to customize
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Python memory allocators.
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.. _pep-442:
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PEP 442: Safe object finalization
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=================================
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This PEP removes the current limitations and quirks of object finalization.
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With it, objects with :meth:`__del__` methods, as well as generators
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with :keyword:`finally` clauses, can be finalized when they are part of a
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reference cycle.
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As part of this change, module globals are no longer forcibly set to
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:const:`None` during interpreter shutdown, instead relying on the normal
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operation of the cyclic garbage collector.
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.. seealso::
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:pep:`442` - Safe object finalization
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PEP written and implemented by Antoine Pitrou
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:pep:`446` - Make newly created file descriptors non-inheritable
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PEP written and implemented by Victor Stinner.
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Other Language Changes
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@ -200,13 +174,25 @@ implementations to interoperate with the standard library and each other.
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For Python 3.4, this module is considered a :term:`provisional API`.
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.. seealso::
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:pep:`3156` - Asynchronous IO Support Rebooted: the "asyncio" Module
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PEP written and implementation led by Guido van Rossum.
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enum
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----
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The new :mod:`enum` module provides a standard implementation of enumeration
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types, allowing other modules (such as :mod:`socket`) to provide more
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informative error messages and better debugging support by replacing opaque
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integer constants with backwards compatible enumeration values.
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The new :mod:`enum` module (defined in :pep:`435`) provides a standard
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implementation of enumeration types, allowing other modules (such as
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:mod:`socket`) to provide more informative error messages and better
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debugging support by replacing opaque integer constants with backwards
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compatible enumeration values.
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.. seealso::
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:pep:`435` - Adding an Enum type to the Python standard library
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PEP written by Barry Warsaw, Eli Bendersky and Ethan Furman,
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implemented by Ethan Furman.
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selectors
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@ -225,6 +211,11 @@ statistics functionality directly in the standard library. This module
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supports calculation of the mean, median, mode, variance and standard
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deviation of a data series.
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.. seealso::
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:pep:`450` - Adding A Statistics Module To The Standard Library
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PEP written and implemented by Steven D'Aprano
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Improved Modules
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================
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@ -366,13 +357,22 @@ inspect
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-------
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The inspect module now offers a basic command line interface to quickly
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display source code and other information for modules, classes and
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functions.
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The inspect module now offers a basic :ref:`command line interface
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<inspect-module-cli>` to quickly display source code and other
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information for modules, classes and functions. (Contributed by Claudiu Popa
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and Nick Coghlan in :issue:`18626`)
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:func:`~inspect.unwrap` makes it easy to unravel wrapper function chains
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created by :func:`functools.wraps` (and any other API that sets the
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``__wrapped__`` attribute on a wrapper function).
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``__wrapped__`` attribute on a wrapper function). (Contributed by
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Daniel Urban, Aaron Iles and Nick Coghlan in :issue:`13266`)
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As part of the implementation of the new :mod:`enum` module, the
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:mod:`inspect` module now has substantially better support for custom
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``__dir__`` methods and dynamic class attributes provided through
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metaclasses (Contributed by Ethan Furman in :issue:`18929` and
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:issue:`19030`)
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mmap
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----
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@ -438,6 +438,15 @@ The :mod:`pprint` module now supports *compact* mode for formatting long
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sequences (:issue:`19132`).
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pydoc
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-----
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While significant changes have not been made to :mod:`pydoc` directly,
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its handling of custom ``__dir__`` methods and various descriptor
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behaviours has been improved substantially by the underlying changes in
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the :mod:`inspect` module.
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resource
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--------
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@ -626,8 +635,46 @@ Major performance enhancements have been added:
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:issue:`9548`)
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Build and C API Changes
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=======================
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CPython Implementation Changes
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==============================
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.. _pep-445:
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PEP 445: Customization of CPython memory allocators
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---------------------------------------------------
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:pep:`445` adds new C level interfaces to customize memory allocation in
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the CPython interpreter.
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.. seealso::
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:pep:`445` - Add new APIs to customize Python memory allocators
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PEP written and implemented by Victor Stinner.
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.. _pep-442:
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PEP 442: Safe object finalization
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---------------------------------
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:pep:`442` removes the current limitations and quirks of object finalization
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in CPython. With it, objects with :meth:`__del__` methods, as well as
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generators with :keyword:`finally` clauses, can be finalized when they are
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part of a reference cycle.
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As part of this change, module globals are no longer forcibly set to
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:const:`None` during interpreter shutdown in most cases, instead relying
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on the normal operation of the cyclic garbage collector.
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.. seealso::
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:pep:`442` - Safe object finalization
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PEP written and implemented by Antoine Pitrou.
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Other build and C API changes
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-----------------------------
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Changes to Python's build process and to the C API include:
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@ -645,6 +692,12 @@ Changes to Python's build process and to the C API include:
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accurate signatures for builtins and standard library extension modules
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implemented in C.
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.. note::
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The Argument Clinic PEP is not fully up to date with the state of the
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implementation. This has been deemed acceptable by the release manager
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and core development team in this case, as Argument Clinic will not
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be made available as a public API for third party use in Python 3.4.
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Deprecated
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==========
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@ -737,12 +790,14 @@ that may require changes to your code.
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exceptions now.
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* :func:`functools.update_wrapper` and :func:`functools.wraps` now correctly
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set the ``__wrapped__`` attribute even if the wrapped function had a
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wrapped attribute set. This means ``__wrapped__`` attributes now correctly
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link a stack of decorated functions rather than every ``__wrapped__``
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attribute in the chain referring to the innermost function. Introspection
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libraries that assumed the previous behaviour was intentional can use
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:func:`inspect.unwrap` to gain equivalent behaviour.
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set the ``__wrapped__`` attribute to the function being wrapper, even if
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that function also had its ``__wrapped__`` attribute set. This means
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``__wrapped__`` attributes now correctly link a stack of decorated
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functions rather than every ``__wrapped__`` attribute in the chain
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referring to the innermost function. Introspection libraries that
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assumed the previous behaviour was intentional can use
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:func:`inspect.unwrap` to access the first function in the chain that has
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no ``__wrapped__`` attribute.
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* (C API) The result of the :c:data:`PyOS_ReadlineFunctionPointer` callback must
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now be a string allocated by :c:func:`PyMem_RawMalloc` or
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