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whatsnew: Inital pass on "What's New in Python 3.6"

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Patch by Elvis Pranskevichus.
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@ -4,6 +4,7 @@
:Release: |release| :Release: |release|
:Date: |today| :Date: |today|
:Editors: Elvis Pranskevichus <elvis@magic.io>, Yury Selivanov <yury@magic.io>
.. Rules for maintenance: .. Rules for maintenance:
@ -45,15 +46,17 @@
This saves the maintainer the effort of going through the Mercurial log This saves the maintainer the effort of going through the Mercurial log
when researching a change. when researching a change.
This article explains the new features in Python 3.6, compared to 3.5.
For full details, see the :ref:`changelog <changelog>`.
.. note:: .. note::
Prerelease users should be aware that this document is currently in draft Prerelease users should be aware that this document is currently in draft
form. It will be updated substantially as Python 3.6 moves towards release, form. It will be updated substantially as Python 3.6 moves towards release,
so it's worth checking back even after reading earlier versions. so it's worth checking back even after reading earlier versions.
This article explains the new features in Python 3.6, compared to 3.5.
.. seealso::
:pep:`494` - Python 3.6 Release Schedule
Summary -- Release highlights Summary -- Release highlights
@ -64,40 +67,73 @@ Summary -- Release highlights
New syntax features: New syntax features:
* A ``global`` or ``nonlocal`` statement must now textually appear * :ref:`PEP 498 <whatsnew36-pep498>`, formatted string literals.
before the first use of the affected name in the same scope.
Previously this was a SyntaxWarning.
* PEP 498: :ref:`Formatted string literals <whatsnew-fstrings>` * :ref:`PEP 515 <whatsnew36-pep515>`, underscores in numeric literals.
* PEP 515: Underscores in Numeric Literals * :ref:`PEP 526 <whatsnew36-pep526>`, syntax for variable annotations.
* PEP 526: :ref:`Syntax for Variable Annotations <variable-annotations>` * :ref:`PEP 525 <whatsnew36-pep525>`, asynchronous generators.
* PEP 525: Asynchronous Generators * :ref:`PEP 530 <whatsnew36-pep530>`: asynchronous comprehensions.
* PEP 530: Asynchronous Comprehensions
Standard library improvements: New library modules:
* :mod:`secrets`: :ref:`PEP 506 -- Adding A Secrets Module To The Standard Library <whatsnew36-pep506>`.
CPython implementation improvements:
* The :ref:`dict <typesmapping>` type has been reimplemented to use
a :ref:`faster, more compact representation <whatsnew36-compactdict>`
similar to the `PyPy dict implementation`_. This resulted in dictionaries
using 20% to 25% less memory when compared to Python 3.5.
* Customization of class creation has been simplified with the
:ref:`new protocol <whatsnew36-pep487>`.
* The class attibute definition order is
:ref:`now preserved <whatsnew36-pep520>`.
* The order of elements in ``**kwargs`` now corresponds to the order in
the function signature:
:ref:`Preserving Keyword Argument Order <whatsnew36-pep468>`.
* DTrace and SystemTap :ref:`probing support <whatsnew36-tracing>`.
Significant improvements in the standard library:
* A new :ref:`file system path protocol <whatsnew36-pep519>` has been
implemented to support :term:`path-like objects <path-like object>`.
All standard library functions operating on paths have been updated to
work with the new protocol.
* The overhead of :mod:`asyncio` implementation has been reduced by
up to 50% thanks to the new C implementation of the :class:`asyncio.Future`
and :class:`asyncio.Task` classes and other optimizations.
Security improvements: Security improvements:
* On Linux, :func:`os.urandom` now blocks until the system urandom entropy pool * On Linux, :func:`os.urandom` now blocks until the system urandom entropy
is initialized to increase the security. See the :pep:`524` for the pool is initialized to increase the security. See the :pep:`524` for the
rationale. rationale.
* :mod:`hashlib` and :mod:`ssl` now support OpenSSL 1.1.0. * The :mod:`hashlib` and :mod:`ssl` modules now support OpenSSL 1.1.0.
* The default settings and feature set of the :mod:`ssl` have been improved. * The default settings and feature set of the :mod:`ssl` module have been
improved.
* The :mod:`hashlib` module received support for the BLAKE2, SHA-3 and SHAKE
hash algorithms and the :func:`~hashlib.scrypt` key derivation function.
* The :mod:`hashlib` module has got support for BLAKE2, SHA-3 and SHAKE hash
algorithms and :func:`~hashlib.scrypt` key derivation function.
Windows improvements: Windows improvements:
* PEP 529: :ref:`Change Windows filesystem encoding to UTF-8 <pep-529>` * :ref:`PEP 528 <whatsnew36-pep529>` and :ref:`PEP 529 <whatsnew36-pep529>`,
Windows filesystem and console encoding changed to UTF-8.
* PEP 528: :ref:`Change Windows console encoding to UTF-8 <pep-528>`
* The ``py.exe`` launcher, when used interactively, no longer prefers * The ``py.exe`` launcher, when used interactively, no longer prefers
Python 2 over Python 3 when the user doesn't specify a version (via Python 2 over Python 3 when the user doesn't specify a version (via
@ -116,66 +152,111 @@ Windows improvements:
:envvar:`PYTHONHOME`. See :ref:`the documentation <finding_modules>` for :envvar:`PYTHONHOME`. See :ref:`the documentation <finding_modules>` for
more information. more information.
.. PEP-sized items next.
.. _pep-4XX:
.. PEP 4XX: Virtual Environments
.. =============================
.. (Implemented by Foo Bar.)
.. .. seealso::
:pep:`4XX` - Python Virtual Environments
PEP written by Carl Meyer
New built-in features:
* PEP 520: :ref:`Preserving Class Attribute Definition Order<whatsnew-deforder>`
* PEP 468: :ref:`Preserving Keyword Argument Order<whatsnew-kwargs>`
A complete list of PEP's implemented in Python 3.6: A complete list of PEP's implemented in Python 3.6:
* :pep:`468`, :ref:`Preserving Keyword Argument Order<whatsnew-kwargs>` * :pep:`468`, :ref:`Preserving Keyword Argument Order <whatsnew36-pep468>`
* :pep:`487`, :ref:`Simpler customization of class creation<whatsnew-pep487>` * :pep:`487`, :ref:`Simpler customization of class creation <whatsnew36-pep487>`
* :pep:`495`, Local Time Disambiguation * :pep:`495`, Local Time Disambiguation
* :pep:`498`, :ref:`Formatted string literals <whatsnew-fstrings>` * :pep:`498`, :ref:`Formatted string literals <whatsnew36-pep498>`
* :pep:`506`, Adding A Secrets Module To The Standard Library * :pep:`506`, Adding A Secrets Module To The Standard Library
* :pep:`509`, :ref:`Add a private version to dict<whatsnew-pep509>` * :pep:`509`, :ref:`Add a private version to dict <whatsnew36-pep509>`
* :pep:`515`, :ref:`Underscores in Numeric Literals<pep-515>` * :pep:`515`, :ref:`Underscores in Numeric Literals <whatsnew36-pep515>`
* :pep:`519`, :ref:`Adding a file system path protocol<pep-519>` * :pep:`519`, :ref:`Adding a file system path protocol <whatsnew36-pep519>`
* :pep:`520`, :ref:`Preserving Class Attribute Definition Order<whatsnew-deforder>` * :pep:`520`, :ref:`Preserving Class Attribute Definition Order <whatsnew36-pep520>`
* :pep:`523`, :ref:`Adding a frame evaluation API to CPython<pep-523>` * :pep:`523`, :ref:`Adding a frame evaluation API to CPython <whatsnew36-pep523>`
* :pep:`524`, Make os.urandom() blocking on Linux (during system startup) * :pep:`524`, Make os.urandom() blocking on Linux (during system startup)
* :pep:`525`, Asynchronous Generators (provisional) * :pep:`525`, Asynchronous Generators (provisional)
* :pep:`526`, :ref:`Syntax for Variable Annotations (provisional)<variable-annotations>` * :pep:`526`, :ref:`Syntax for Variable Annotations (provisional) <whatsnew36-pep526>`
* :pep:`528`, :ref:`Change Windows console encoding to UTF-8 (provisional)<pep-528>` * :pep:`528`, :ref:`Change Windows console encoding to UTF-8 (provisional) <whatsnew36-pep528>`
* :pep:`529`, :ref:`Change Windows filesystem encoding to UTF-8 (provisional)<pep-529>` * :pep:`529`, :ref:`Change Windows filesystem encoding to UTF-8 (provisional) <whatsnew36-pep529>`
* :pep:`530`, Asynchronous Comprehensions * :pep:`530`, Asynchronous Comprehensions
.. _PyPy dict implementation: https://morepypy.blogspot.com/2015/01/faster-more-memory-efficient-and-more.html
New Features New Features
============ ============
.. _pep-515: .. _whatsnew36-pep498:
PEP 498: Formatted string literals
----------------------------------
:pep:`498` introduces a new kind of string literals: *f-strings*, or
*formatted string literals*.
Formatted string literals are prefixed with ``'f'`` and are similar to
the format strings accepted by :meth:`str.format`. They contain replacement
fields surrounded by curly braces. The replacement fields are expressions,
which are evaluated at run time, and then formatted using the
:func:`format` protocol::
>>> name = "Fred"
>>> f"He said his name is {name}."
'He said his name is Fred.'
.. seealso::
:pep:`498` -- Literal String Interpolation.
PEP written and implemented by Eric V. Smith.
:ref:`Feature documentation <f-strings>`.
.. _whatsnew36-pep526:
PEP 526: Syntax for variable annotations
----------------------------------------
:pep:`484` introduced the standard for type annotations of function
parameters, a.k.a. type hints. This PEP adds syntax to Python for annotating
the types of variables including class variables and instance variables::
primes: List[int] = []
captain: str # Note: no initial value!
class Starship:
stats: Dict[str, int] = {}
Just as for function annotations, the Python interpreter does not attach any
particular meaning to variable annotations and only stores them in the
``__annotations__`` attribute of a class or module.
In contrast to variable declarations in statically typed languages,
the goal of annotation syntax is to provide an easy way to specify structured
type metadata for third party tools and libraries via the abstract syntax tree
and the ``__annotations__`` attribute.
.. seealso::
:pep:`526` -- Syntax for variable annotations.
PEP written by Ryan Gonzalez, Philip House, Ivan Levkivskyi, Lisa Roach,
and Guido van Rossum. Implemented by Ivan Levkivskyi.
Tools that use or will use the new syntax:
`mypy <http://github.com/python/mypy>`_,
`pytype <http://github.com/google/pytype>`_, PyCharm, etc.
.. _whatsnew36-pep515:
PEP 515: Underscores in Numeric Literals PEP 515: Underscores in Numeric Literals
---------------------------------------- ----------------------------------------
Prior to PEP 515, there was no support for writing long numeric :pep:`515` adds the ability to use underscores in numeric literals for
literals with some form of separator to improve readability. For improved readability. For example::
instance, how big is ``1000000000000000``? With :pep:`515`, though,
you can use underscores to separate digits as desired to make numeric >>> 1_000_000_000_000_000
literals easier to read: ``1_000_000_000_000_000``. Underscores can be 1000000000000000
used with other numeric literals beyond integers, e.g. >>> 0x_FF_FF_FF_FF
``0x_FF_FF_FF_FF``. 4294967295
Single underscores are allowed between digits and after any base Single underscores are allowed between digits and after any base
specifier. More than a single underscore in a row, leading, or specifier. Leading, trailing, or multiple underscores in a row are not
trailing underscores are not allowed. allowed.
.. seealso:: .. seealso::
@ -183,36 +264,115 @@ trailing underscores are not allowed.
PEP written by Georg Brandl and Serhiy Storchaka. PEP written by Georg Brandl and Serhiy Storchaka.
.. _pep-523: .. _whatsnew36-pep525:
PEP 523: Adding a frame evaluation API to CPython PEP 525: Asynchronous Generators
------------------------------------------------- --------------------------------
While Python provides extensive support to customize how code :pep:`492` introduced support for native coroutines and ``async`` / ``await``
executes, one place it has not done so is in the evaluation of frame syntax to Python 3.5. A notable limitation of the Python 3.5 implementation
objects. If you wanted some way to intercept frame evaluation in is that it was not possible to use ``await`` and ``yield`` in the same
Python there really wasn't any way without directly manipulating function body. In Python 3.6 this restriction has been lifted, making it
function pointers for defined functions. possible to define *asynchronous generators*::
:pep:`523` changes this by providing an API to make frame async def ticker(delay, to):
evaluation pluggable at the C level. This will allow for tools such """Yield numbers from 0 to `to` every `delay` seconds."""
as debuggers and JITs to intercept frame evaluation before the for i in range(to):
execution of Python code begins. This enables the use of alternative yield i
evaluation implementations for Python code, tracking frame await asyncio.sleep(delay)
evaluation, etc.
This API is not part of the limited C API and is marked as private to The new syntax allows for faster and more concise code.
signal that usage of this API is expected to be limited and only
applicable to very select, low-level use-cases. Semantics of the
API will change with Python as necessary.
.. seealso:: .. seealso::
:pep:`523` -- Adding a frame evaluation API to CPython :pep:`525` -- Asynchronous Generators
PEP written by Brett Cannon and Dino Viehland. PEP written and implemented by Yury Selivanov.
.. _pep-519: .. _whatsnew36-pep530:
PEP 530: Asynchronous Comprehensions
------------------------------------
:pep:`530` adds support for using ``async for`` in list, set, dict
comprehensions and generator expressions::
result = [i async for i in aiter() if i % 2]
Additionally, ``await`` expressions are supported in all kinds
of comprehensions::
result = [await fun() for fun in funcs]
.. seealso::
:pep:`530` -- Asynchronous Comprehensions
PEP written and implemented by Yury Selivanov.
.. _whatsnew36-pep487:
PEP 487: Simpler customization of class creation
------------------------------------------------
It is now possible to customize subclass creation without using a metaclass.
The new ``__init_subclass__`` classmethod will be called on the base class
whenever a new subclass is created::
>>> class QuestBase:
... # this is implicitly a @classmethod
... def __init_subclass__(cls, swallow, **kwargs):
... cls.swallow = swallow
... super().__init_subclass__(**kwargs)
>>> class Quest(QuestBase, swallow="african"):
... pass
>>> Quest.swallow
'african'
.. seealso::
:pep:`487` -- Simpler customization of class creation
PEP written and implemented by Martin Teichmann.
:ref:`Feature documentation <class-customization>`
.. _whatsnew36-pep487-descriptors:
PEP 487: Descriptor Protocol Enhancements
-----------------------------------------
:pep:`487` extends the descriptor protocol has to include the new optional
``__set_name__`` method. Whenever a new class is defined, the new method
will be called on all descriptors included in the definition, providing
them with a reference to the class being defined and the name given to the
descriptor within the class namespace.
.. seealso::
:pep:`487` -- Simpler customization of class creation
PEP written and implemented by Martin Teichmann.
:ref:`Feature documentation <descriptors>`
.. _whatsnew36-pep506:
PEP 506: Adding A Secrets Module To The Standard Library
--------------------------------------------------------
.. seealso::
:pep:`506` -- Adding A Secrets Module To The Standard Library
PEP written and implemented by Steven D'Aprano.
.. _whatsnew36-pep519:
PEP 519: Adding a file system path protocol PEP 519: Adding a file system path protocol
------------------------------------------- -------------------------------------------
@ -279,60 +439,7 @@ pre-existing code::
PEP written by Brett Cannon and Koos Zevenhoven. PEP written by Brett Cannon and Koos Zevenhoven.
.. _whatsnew-fstrings: .. _whatsnew36-pep529:
PEP 498: Formatted string literals
----------------------------------
Formatted string literals are a new kind of string literal, prefixed
with ``'f'``. They are similar to the format strings accepted by
:meth:`str.format`. They contain replacement fields surrounded by
curly braces. The replacement fields are expressions, which are
evaluated at run time, and then formatted using the :func:`format` protocol::
>>> name = "Fred"
>>> f"He said his name is {name}."
'He said his name is Fred.'
See :pep:`498` and the main documentation at :ref:`f-strings`.
.. _variable-annotations:
PEP 526: Syntax for variable annotations
----------------------------------------
:pep:`484` introduced standard for type annotations of function parameters,
a.k.a. type hints. This PEP adds syntax to Python for annotating the
types of variables including class variables and instance variables::
primes: List[int] = []
captain: str # Note: no initial value!
class Starship:
stats: Dict[str, int] = {}
Just as for function annotations, the Python interpreter does not attach any
particular meaning to variable annotations and only stores them in a special
attribute ``__annotations__`` of a class or module.
In contrast to variable declarations in statically typed languages,
the goal of annotation syntax is to provide an easy way to specify structured
type metadata for third party tools and libraries via the abstract syntax tree
and the ``__annotations__`` attribute.
.. seealso::
:pep:`526` -- Syntax for variable annotations.
PEP written by Ryan Gonzalez, Philip House, Ivan Levkivskyi, Lisa Roach,
and Guido van Rossum. Implemented by Ivan Levkivskyi.
Tools that use or will use the new syntax:
`mypy <http://github.com/python/mypy>`_,
`pytype <http://github.com/google/pytype>`_, PyCharm, etc.
.. _pep-529:
PEP 529: Change Windows filesystem encoding to UTF-8 PEP 529: Change Windows filesystem encoding to UTF-8
---------------------------------------------------- ----------------------------------------------------
@ -355,28 +462,8 @@ correctly encoded. To revert to the previous behaviour, set
See :pep:`529` for more information and discussion of code modifications that See :pep:`529` for more information and discussion of code modifications that
may be required. may be required.
.. _whatsnew-pep487:
PEP 487: Simpler customization of class creation .. _whatsnew36-pep528:
------------------------------------------------
Upon subclassing a class, the ``__init_subclass__`` classmethod (if defined) is
called on the base class. This makes it straightforward to write classes that
customize initialization of future subclasses without introducing the
complexity of a full custom metaclass.
The descriptor protocol has also been expanded to include a new optional method,
``__set_name__``. Whenever a new class is defined, the new method will be called
on all descriptors included in the definition, providing them with a reference
to the class being defined and the name given to the descriptor within the
class namespace.
Also see :pep:`487` and the updated class customization documentation at
:ref:`class-customization` and :ref:`descriptors`.
(Contributed by Martin Teichmann in :issue:`27366`)
.. _pep-528:
PEP 528: Change Windows console encoding to UTF-8 PEP 528: Change Windows console encoding to UTF-8
------------------------------------------------- -------------------------------------------------
@ -394,6 +481,104 @@ console use, set :envvar:`PYTHONLEGACYWINDOWSIOENCODING`.
:pep:`528` -- Change Windows console encoding to UTF-8 :pep:`528` -- Change Windows console encoding to UTF-8
PEP written and implemented by Steve Dower. PEP written and implemented by Steve Dower.
.. _whatsnew36-pep520:
PEP 520: Preserving Class Attribute Definition Order
----------------------------------------------------
Attributes in a class definition body have a natural ordering: the same
order in which the names appear in the source. This order is now
preserved in the new class's ``__dict__`` attribute.
Also, the effective default class *execution* namespace (returned from
``type.__prepare__()``) is now an insertion-order-preserving mapping.
.. seealso::
:pep:`520` -- Preserving Class Attribute Definition Order
PEP written and implemented by Eric Snow.
.. _whatsnew36-pep468:
PEP 468: Preserving Keyword Argument Order
------------------------------------------
``**kwargs`` in a function signature is now guaranteed to be an
insertion-order-preserving mapping.
.. seealso::
:pep:`468` -- Preserving Keyword Argument Order
PEP written and implemented by Eric Snow.
.. _whatsnew36-compactdict:
New :ref:`dict <typesmapping>` implementation
---------------------------------------------
The :ref:`dict <typesmapping>` type now uses a "compact" representation
`pioneered by PyPy <https://morepypy.blogspot.com/2015/01/faster-more-memory-efficient-and-more.html>`_.
The memory usage of the new :func:`dict` is between 20% and 25% smaller
compared to Python 3.5.
:pep:`468` (Preserving the order of ``**kwargs`` in a function.) is
implemented by this. The order-preserving aspect of this new
implementation is considered an implementation detail and should
not be relied upon (this may change in the future, but it is desired
to have this new dict implementation in the language for a few
releases before changing the language spec to mandate
order-preserving semantics for all current and future Python
implementations; this also helps preserve backwards-compatibility
with older versions of the language where random iteration order is
still in effect, e.g. Python 3.5).
(Contributed by INADA Naoki in :issue:`27350`. Idea
`originally suggested by Raymond Hettinger
<https://mail.python.org/pipermail/python-dev/2012-December/123028.html>`_.)
.. _whatsnew36-pep523:
PEP 523: Adding a frame evaluation API to CPython
-------------------------------------------------
While Python provides extensive support to customize how code
executes, one place it has not done so is in the evaluation of frame
objects. If you wanted some way to intercept frame evaluation in
Python there really wasn't any way without directly manipulating
function pointers for defined functions.
:pep:`523` changes this by providing an API to make frame
evaluation pluggable at the C level. This will allow for tools such
as debuggers and JITs to intercept frame evaluation before the
execution of Python code begins. This enables the use of alternative
evaluation implementations for Python code, tracking frame
evaluation, etc.
This API is not part of the limited C API and is marked as private to
signal that usage of this API is expected to be limited and only
applicable to very select, low-level use-cases. Semantics of the
API will change with Python as necessary.
.. seealso::
:pep:`523` -- Adding a frame evaluation API to CPython
PEP written by Brett Cannon and Dino Viehland.
.. _whatsnew36-pep509:
PEP 509: Add a private version to dict
--------------------------------------
Add a new private version to the builtin ``dict`` type, incremented at
each dictionary creation and at each dictionary change, to implement
fast guards on namespaces.
(Contributed by Victor Stinner in :issue:`26058`.)
PYTHONMALLOC environment variable PYTHONMALLOC environment variable
--------------------------------- ---------------------------------
@ -468,6 +653,8 @@ Example of fatal error on buffer overflow using
(Contributed by Victor Stinner in :issue:`26516` and :issue:`26564`.) (Contributed by Victor Stinner in :issue:`26516` and :issue:`26564`.)
.. _whatsnew36-tracing:
DTrace and SystemTap probing support DTrace and SystemTap probing support
------------------------------------ ------------------------------------
@ -493,71 +680,14 @@ markers may be added in the future.
Jesús Cea Avión, David Malcolm, and Nikhil Benesch.) Jesús Cea Avión, David Malcolm, and Nikhil Benesch.)
.. _whatsnew-deforder:
PEP 520: Preserving Class Attribute Definition Order
----------------------------------------------------
Attributes in a class definition body have a natural ordering: the same
order in which the names appear in the source. This order is now
preserved in the new class's ``__dict__`` attribute.
Also, the effective default class *execution* namespace (returned from
``type.__prepare__()``) is now an insertion-order-preserving mapping.
.. seealso::
:pep:`520` -- Preserving Class Attribute Definition Order
PEP written and implemented by Eric Snow.
.. _whatsnew-kwargs:
PEP 468: Preserving Keyword Argument Order
------------------------------------------
``**kwargs`` in a function signature is now guaranteed to be an
insertion-order-preserving mapping.
.. seealso::
:pep:`468` -- Preserving Keyword Argument Order
PEP written and implemented by Eric Snow.
.. _whatsnew-pep509:
PEP 509: Add a private version to dict
--------------------------------------
Add a new private version to the builtin ``dict`` type, incremented at
each dictionary creation and at each dictionary change, to implement
fast guards on namespaces.
(Contributed by Victor Stinner in :issue:`26058`.)
Other Language Changes Other Language Changes
====================== ======================
Some smaller changes made to the core Python language are: Some smaller changes made to the core Python language are:
* :func:`dict` now uses a "compact" representation `pioneered by PyPy * A ``global`` or ``nonlocal`` statement must now textually appear
<https://morepypy.blogspot.com/2015/01/faster-more-memory-efficient-and-more.html>`_. before the first use of the affected name in the same scope.
The memory usage of the new :func:`dict` is between 20% and 25% smaller Previously this was a ``SyntaxWarning``.
compared to Python 3.5.
:pep:`468` (Preserving the order of ``**kwargs`` in a function.) is
implemented by this. The order-preserving aspect of this new
implementation is considered an implementation detail and should
not be relied upon (this may change in the future, but it is desired
to have this new dict implementation in the language for a few
releases before changing the language spec to mandate
order-preserving semantics for all current and future Python
implementations; this also helps preserve backwards-compatibility
with older versions of the language where random iteration order is
still in effect, e.g. Python 3.5).
(Contributed by INADA Naoki in :issue:`27350`. Idea
`originally suggested by Raymond Hettinger
<https://mail.python.org/pipermail/python-dev/2012-December/123028.html>`_.)
* Long sequences of repeated traceback lines are now abbreviated as * Long sequences of repeated traceback lines are now abbreviated as
``"[Previous line repeated {count} more times]"`` (see ``"[Previous line repeated {count} more times]"`` (see
@ -572,16 +702,15 @@ Some smaller changes made to the core Python language are:
New Modules New Modules
=========== ===========
* None yet. secrets
-------
The new :mod:`secrets` module.
Improved Modules Improved Modules
================ ================
On Linux, :func:`os.urandom` now blocks until the system urandom entropy pool
is initialized to increase the security. See the :pep:`524` for the rationale.
asyncio asyncio
------- -------
@ -783,11 +912,14 @@ iterator is neither exhausted nor explicitly closed a :exc:`ResourceWarning`
will be emitted in its destructor. will be emitted in its destructor.
(Contributed by Serhiy Storchaka in :issue:`25994`.) (Contributed by Serhiy Storchaka in :issue:`25994`.)
On Linux, :func:`os.urandom` now blocks until the system urandom entropy pool
is initialized to increase the security. See the :pep:`524` for the rationale.
The Linux ``getrandom()`` syscall (get random bytes) is now exposed as the new The Linux ``getrandom()`` syscall (get random bytes) is now exposed as the new
:func:`os.getrandom` function. :func:`os.getrandom` function.
(Contributed by Victor Stinner, part of the :pep:`524`) (Contributed by Victor Stinner, part of the :pep:`524`)
See the summary for :ref:`PEP 519 <pep-519>` for details on how the See the summary for :ref:`PEP 519 <whatsnew36-pep519>` for details on how the
:mod:`os` and :mod:`os.path` modules now support :mod:`os` and :mod:`os.path` modules now support
:term:`path-like objects <path-like object>`. :term:`path-like objects <path-like object>`.
@ -1159,6 +1291,7 @@ Optimizations
it is now about 1.5--4 times faster. it is now about 1.5--4 times faster.
(Contributed by Serhiy Storchaka in :issue:`26032`). (Contributed by Serhiy Storchaka in :issue:`26032`).
Build and C API Changes Build and C API Changes
======================= =======================