mirror of https://github.com/python/cpython
bpo-37759: More updates to Whatsnew 3.8 (GH-16854)
* math.perm() and math.comb() * math.isqrt() * Add singledispatchmethod() * itertools.accumulate() * Optional headers for xmlrpc.client.ServerProxy * IDLE non-BMP characters * import collections.abc directly * @coroutine is deprecated * pprint.pp() * New options for object.__reduce__() * DictReader no longer returns OrderedDicts * "force" option for logging.basicConfig() * Fix spelling * cProfile context manager * Various markup/grammar fixes from Kyle Stanley. Other minor fixes as well. Also, dedup the __reduce__ entry. * Fix markup * Fix grammar nits found by MS Word
This commit is contained in:
Raymond Hettinger
GitHub
parent
58ccd201fa
commit
c93883c6af
|
|
@ -355,8 +355,8 @@ It is meant to formalize existing optimizations which were already done
|
|||
for various classes.
|
||||
Any extension type implementing a callable can use this protocol.
|
||||
|
||||
This is currently provisional,
|
||||
the aim is to make it fully public in Python 3.9.
|
||||
This is currently provisional.
|
||||
The aim is to make it fully public in Python 3.9.
|
||||
|
||||
See :pep:`590` for a full description.
|
||||
|
||||
|
|
@ -445,7 +445,7 @@ Other Language Changes
|
|||
an instance of the subclass, rather than the base class. This also affects
|
||||
the return type of operations whose implementation (directly or indirectly)
|
||||
uses :class:`datetime.timedelta` arithmetic, such as
|
||||
:meth:`datetime.datetime.astimezone`.
|
||||
:meth:`~datetime.datetime.astimezone`.
|
||||
(Contributed by Paul Ganssle in :issue:`32417`.)
|
||||
|
||||
* When the Python interpreter is interrupted by Ctrl-C (SIGINT) and the
|
||||
|
|
@ -529,6 +529,13 @@ Other Language Changes
|
|||
|
||||
(Contributed by Jörn Heissler in :issue:`35224`.)
|
||||
|
||||
* The :meth:`object.__reduce__` method can now return a tuple from two to
|
||||
six elements long. Formerly, five was the limit. The new, optional sixth
|
||||
element is a callable with a ``(obj, state)`` signature. This allows the
|
||||
direct control over the state-updating behavior of a specific object. If
|
||||
not *None*, this callable will have priority over the object's
|
||||
:meth:`~__setstate__` method.
|
||||
(Contributed by Pierre Glaser and Olivier Grisel in :issue:`35900`.)
|
||||
|
||||
New Modules
|
||||
===========
|
||||
|
|
@ -579,8 +586,8 @@ The :func:`ast.parse` function has some new flags:
|
|||
comments" (returned for function definition AST nodes);
|
||||
|
||||
* ``feature_version=(3, N)`` allows specifying an earlier Python 3
|
||||
version. (For example, ``feature_version=(3, 4)`` will treat
|
||||
``async`` and ``await`` as non-reserved words.)
|
||||
version. For example, ``feature_version=(3, 4)`` will treat
|
||||
:keyword:`async` and :keyword:`await` as non-reserved words.
|
||||
|
||||
(Contributed by Guido van Rossum in :issue:`35766`.)
|
||||
|
||||
|
|
@ -630,14 +637,39 @@ marked with the ``CO_COROUTINE`` flag may then be returned.
|
|||
collections
|
||||
-----------
|
||||
|
||||
The :meth:`_asdict()` method for :func:`collections.namedtuple` now returns
|
||||
a :class:`dict` instead of a :class:`collections.OrderedDict`. This works because
|
||||
regular dicts have guaranteed ordering since Python 3.7. If the extra
|
||||
features of :class:`OrderedDict` are required, the suggested remediation is
|
||||
to cast the result to the desired type: ``OrderedDict(nt._asdict())``.
|
||||
The :meth:`~collections.somenamedtuple._asdict` method for
|
||||
:func:`collections.namedtuple` now returns a :class:`dict` instead of a
|
||||
:class:`collections.OrderedDict`. This works because regular dicts have
|
||||
guaranteed ordering since Python 3.7. If the extra features of
|
||||
:class:`OrderedDict` are required, the suggested remediation is to cast the
|
||||
result to the desired type: ``OrderedDict(nt._asdict())``.
|
||||
(Contributed by Raymond Hettinger in :issue:`35864`.)
|
||||
|
||||
|
||||
cProfile
|
||||
--------
|
||||
|
||||
The :class:`cProfile.Profile <profile.Profile>` class can now be used as a context manager.
|
||||
Profile a block of code by running::
|
||||
|
||||
import cProfile
|
||||
|
||||
with cProfile.Profile() as profiler:
|
||||
# code to be profiled
|
||||
...
|
||||
|
||||
(Contributed by Scott Sanderson in :issue:`29235`.)
|
||||
|
||||
|
||||
csv
|
||||
---
|
||||
|
||||
The :class:`csv.DictReader` now returns instances of :class:`dict` instead of
|
||||
a :class:`collections.OrderedDict`. The tool is now faster and uses less
|
||||
memory while still preserving the field order.
|
||||
(Contributed by Michael Seek in :issue:`34003`.)
|
||||
|
||||
|
||||
curses
|
||||
-------
|
||||
|
||||
|
|
@ -700,6 +732,30 @@ cached for the life of the instance. ::
|
|||
(Contributed by Carl Meyer in :issue:`21145`)
|
||||
|
||||
|
||||
Added a new :func:`functools.singledispatchmethod` decorator that converts
|
||||
methods into :term:`generic functions <generic function>` using
|
||||
:term:`single dispatch`::
|
||||
|
||||
from functools import singledispatchmethod
|
||||
from contextlib import suppress
|
||||
|
||||
class TaskManager:
|
||||
|
||||
def __init__(self, tasks):
|
||||
self.tasks = list(tasks)
|
||||
|
||||
@singledispatchmethod
|
||||
def discard(self, value):
|
||||
with suppress(ValueError):
|
||||
self.tasks.remove(value)
|
||||
|
||||
@discard.register(list)
|
||||
def _(self, tasks):
|
||||
targets = set(tasks)
|
||||
self.tasks = [x for x in self.tasks if x not in targets]
|
||||
|
||||
(Contributed by Ethan Smith in :issue:`32380`)
|
||||
|
||||
gc
|
||||
--
|
||||
|
||||
|
|
@ -727,7 +783,7 @@ for certain types of invalid or corrupt gzip files.
|
|||
:issue:`6584`.)
|
||||
|
||||
|
||||
idlelib and IDLE
|
||||
IDLE and idlelib
|
||||
----------------
|
||||
|
||||
Output over N lines (50 by default) is squeezed down to a button.
|
||||
|
|
@ -743,12 +799,19 @@ They also re-appear in the box for the next customized run. One can also
|
|||
suppress the normal Shell main module restart. (Contributed by Cheryl
|
||||
Sabella, Terry Jan Reedy, and others in :issue:`5680` and :issue:`37627`.)
|
||||
|
||||
Add optional line numbers for IDLE editor windows. Windows
|
||||
Added optional line numbers for IDLE editor windows. Windows
|
||||
open without line numbers unless set otherwise in the General
|
||||
tab of the configuration dialog. Line numbers for an existing
|
||||
window are shown and hidden in the Options menu.
|
||||
(Contributed by Tal Einat and Saimadhav Heblikar in :issue:`17535`.)
|
||||
|
||||
OS native encoding is now used for converting between Python strings and Tcl
|
||||
objects. This allows IDLE to work with emoji and other non-BMP characters.
|
||||
These characters can be displayed or copied and pasted to or from the
|
||||
clipboard. Converting strings from Tcl to Python and back now never fails.
|
||||
(Many people worked on this for eight years but the problem was finally
|
||||
solved by Serhiy Storchaka in :issue:`13153`.)
|
||||
|
||||
The changes above have been backported to 3.7 maintenance releases.
|
||||
|
||||
|
||||
|
|
@ -779,13 +842,44 @@ fails. The exception is ignored silently by default in release build.
|
|||
(Contributed by Victor Stinner in :issue:`18748`.)
|
||||
|
||||
|
||||
itertools
|
||||
---------
|
||||
|
||||
The :func:`itertools.accumulate` function added an option *initial* keyword
|
||||
argument to specify an initial value::
|
||||
|
||||
>>> from itertools import accumulate
|
||||
>>> list(accumulate([10, 5, 30, 15], initial=1000))
|
||||
[1000, 1010, 1015, 1045, 1060]
|
||||
|
||||
(Contributed by Lisa Roach in :issue:`34659`.)
|
||||
|
||||
|
||||
json.tool
|
||||
---------
|
||||
|
||||
Add option ``--json-lines`` to parse every input line as separate JSON object.
|
||||
Add option ``--json-lines`` to parse every input line as a separate JSON object.
|
||||
(Contributed by Weipeng Hong in :issue:`31553`.)
|
||||
|
||||
|
||||
logging
|
||||
-------
|
||||
|
||||
Added a *force* keyword argument to :func:`logging.basicConfig()`
|
||||
When set to *True*, any existing handlers attached
|
||||
to the root logger are removed and closed before carrying out the
|
||||
configuration specified by the other arguments.
|
||||
|
||||
This solves a long-standing problem. Once a logger or *basicConfig()* had
|
||||
been called, subsequent calls to *basicConfig()* were silently ignored.
|
||||
This made it difficult to update, experiment with, or teach the various
|
||||
logging configuration options using the interactive prompt or a Jupyter
|
||||
notebook.
|
||||
|
||||
(Suggested by Raymond Hettinger, implemented by Dong-hee Na, and
|
||||
reviewed by Vinay Sajip in :issue:`33897`.)
|
||||
|
||||
|
||||
math
|
||||
----
|
||||
|
||||
|
|
@ -807,7 +901,28 @@ numbers::
|
|||
|
||||
(Contributed by Pablo Galindo in :issue:`35606`.)
|
||||
|
||||
Added new function :func:`math.isqrt` for computing integer square roots.
|
||||
Added two new combinatoric functions :func:`math.perm` and :func:`math.comb`::
|
||||
|
||||
>>> math.perm(10, 3) # Permutations of 10 things taken 3 at a time
|
||||
720
|
||||
>>> math.comb(10, 3) # Combinations of 10 things taken 3 at a time
|
||||
120
|
||||
|
||||
(Contributed by Yash Aggarwal, Keller Fuchs, Serhiy Storchaka, and Raymond
|
||||
Hettinger in :issue:`37128`, :issue:`37178`, and :issue:`35431`.)
|
||||
|
||||
Added a new function :func:`math.isqrt` for computing accurate integer square
|
||||
roots without conversion to floating point. The new function supports
|
||||
arbitrarily large integers. It is faster than ``floor(sqrt(n))`` but slower
|
||||
than :func:`math.sqrt`::
|
||||
|
||||
>>> r = 650320427
|
||||
>>> s = r ** 2
|
||||
>>> isqrt(s - 1) # correct
|
||||
650320426
|
||||
>>> floor(sqrt(s - 1)) # incorrect
|
||||
650320427
|
||||
|
||||
(Contributed by Mark Dickinson in :issue:`36887`.)
|
||||
|
||||
The function :func:`math.factorial` no longer accepts arguments that are not
|
||||
|
|
@ -908,11 +1023,6 @@ to a path.
|
|||
pickle
|
||||
------
|
||||
|
||||
Reduction methods can now include a 6th item in the tuple they return. This
|
||||
item should specify a custom state-setting method that's called instead of the
|
||||
regular ``__setstate__`` method.
|
||||
(Contributed by Pierre Glaser and Olivier Grisel in :issue:`35900`.)
|
||||
|
||||
:mod:`pickle` extensions subclassing the C-optimized :class:`~pickle.Pickler`
|
||||
can now override the pickling logic of functions and classes by defining the
|
||||
special :meth:`~pickle.Pickler.reducer_override` method.
|
||||
|
|
@ -927,6 +1037,32 @@ NSKeyedArchiver-encoded binary plists.
|
|||
(Contributed by Jon Janzen in :issue:`26707`.)
|
||||
|
||||
|
||||
pprint
|
||||
------
|
||||
|
||||
The :mod:`pprint` module added a *sort_dicts* parameter to several functions.
|
||||
By default, those functions continue to sort dictionaries before rendering or
|
||||
printing. However, if *sort_dicts* is set to *False*, the dictionaries retain
|
||||
the order that keys were inserted. This can be useful for comparison to JSON
|
||||
inputs during debugging.
|
||||
|
||||
In addition, there is a convenience new function, :func:`pprint.pp` that is
|
||||
like :func:`pprint.pprint` but with *sort_dicts* defaulting to *False*::
|
||||
|
||||
>>> from pprint import pprint, pp
|
||||
>>> d = dict(source='input.txt', operation='filter', destination='output.txt')
|
||||
>>> pp(d, width=40) # Original order
|
||||
{'source': 'input.txt',
|
||||
'operation': 'filter',
|
||||
'destination': 'output.txt'}
|
||||
>>> pprint(d, width=40) # Keys sorted alphabetically
|
||||
{'destination': 'output.txt',
|
||||
'operation': 'filter',
|
||||
'source': 'input.txt'}
|
||||
|
||||
(Contributed by Rémi Lapeyre in :issue:`30670`.)
|
||||
|
||||
|
||||
py_compile
|
||||
----------
|
||||
|
||||
|
|
@ -973,8 +1109,8 @@ The :func:`socket.if_nameindex()`, :func:`socket.if_nametoindex()`, and
|
|||
ssl
|
||||
---
|
||||
|
||||
Added :attr:`ssl.SSLContext.post_handshake_auth` to enable and
|
||||
:meth:`ssl.SSLSocket.verify_client_post_handshake` to initiate TLS 1.3
|
||||
Added :attr:`~ssl.SSLContext.post_handshake_auth` to enable and
|
||||
:meth:`~ssl.SSLSocket.verify_client_post_handshake` to initiate TLS 1.3
|
||||
post-handshake authentication.
|
||||
(Contributed by Christian Heimes in :issue:`34670`.)
|
||||
|
||||
|
|
@ -1152,8 +1288,9 @@ the string. (Contributed by Max Belanger, David Euresti, and Greg Price in
|
|||
unittest
|
||||
--------
|
||||
|
||||
Added :class:`AsyncMock` to support an asynchronous version of :class:`Mock`.
|
||||
Appropriate new assert functions for testing have been added as well.
|
||||
Added :class:`~unittest.mock.AsyncMock` to support an asynchronous version of
|
||||
:class:`~unittest.mock.Mock`. Appropriate new assert functions for testing
|
||||
have been added as well.
|
||||
(Contributed by Lisa Roach in :issue:`26467`).
|
||||
|
||||
Added :func:`~unittest.addModuleCleanup()` and
|
||||
|
|
@ -1233,6 +1370,16 @@ them in the generated tree.
|
|||
(Contributed by Stefan Behnel in :issue:`36676` and :issue:`36673`.)
|
||||
|
||||
|
||||
xmlrpc
|
||||
------
|
||||
|
||||
:class:`xmlrpc.client.ServerProxy` now supports an optional *headers* keyword
|
||||
argument for a sequence of HTTP headers to be sent with each request. Among
|
||||
other things, this makes it possible to upgrade from default basic
|
||||
authentication to faster session authentication.
|
||||
(Contributed by Cédric Krier in :issue:`35153`.)
|
||||
|
||||
|
||||
Optimizations
|
||||
=============
|
||||
|
||||
|
|
@ -1456,6 +1603,11 @@ Deprecated
|
|||
constant nodes.
|
||||
(Contributed by Serhiy Storchaka in :issue:`36917`.)
|
||||
|
||||
* The :func:`asyncio.coroutine` :term:`decorator` is deprecated and will be
|
||||
removed in version 3.10. Instead of ``@asyncio.coroutine``, use
|
||||
:keyword:`async def` instead.
|
||||
(Contributed by Andrew Svetlov in :issue:`36921`.)
|
||||
|
||||
* The following functions and methods are deprecated in the :mod:`gettext`
|
||||
module: :func:`~gettext.lgettext`, :func:`~gettext.ldgettext`,
|
||||
:func:`~gettext.lngettext` and :func:`~gettext.ldngettext`.
|
||||
|
|
@ -1502,7 +1654,7 @@ Deprecated
|
|||
:class:`multiprocessing.managers.SharedMemoryServer`.
|
||||
- *obj* in :func:`weakref.finalize`.
|
||||
|
||||
In future releases of Python they will be :ref:`positional-only
|
||||
In future releases of Python, they will be :ref:`positional-only
|
||||
<positional-only_parameter>`.
|
||||
(Contributed by Serhiy Storchaka in :issue:`36492`.)
|
||||
|
||||
|
|
@ -1512,6 +1664,11 @@ API and Feature Removals
|
|||
|
||||
The following features and APIs have been removed from Python 3.8:
|
||||
|
||||
* Starting with Python 3.3, importing ABCs from :mod:`collections` was
|
||||
deprecated, and importing should be done from :mod:`collections.abc`. Being
|
||||
able to import from collections was marked for removal in 3.8, but has been
|
||||
delayed to 3.9. (See :issue:`36952`.)
|
||||
|
||||
* The :mod:`macpath` module, deprecated in Python 3.7, has been removed.
|
||||
(Contributed by Victor Stinner in :issue:`35471`.)
|
||||
|
||||
|
|
@ -1630,7 +1787,7 @@ Changes in the Python API
|
|||
(Contributed by Eric Snow in :issue:`34651`, modified by Christian Heimes
|
||||
in :issue:`37951`.)
|
||||
|
||||
* The :meth:`imap.IMAP4.logout` method no longer ignores silently arbitrary
|
||||
* The :meth:`imap.IMAP4.logout` method no longer silently ignores arbitrary
|
||||
exceptions.
|
||||
(Contributed by Victor Stinner in :issue:`36348`.)
|
||||
|
||||
|
|
@ -1685,7 +1842,7 @@ Changes in the Python API
|
|||
* The ``PyGC_Head`` struct has changed completely. All code that touched the
|
||||
struct member should be rewritten. (See :issue:`33597`.)
|
||||
|
||||
* The ``PyInterpreterState`` struct has been moved into the "internal"
|
||||
* The :c:type:`PyInterpreterState` struct has been moved into the "internal"
|
||||
header files (specifically Include/internal/pycore_pystate.h). An
|
||||
opaque ``PyInterpreterState`` is still available as part of the public
|
||||
API (and stable ABI). The docs indicate that none of the struct's
|
||||
|
|
|
|||
Loading…
Reference in New Issue