mirror of https://github.com/python/cpython.git
2364 lines
90 KiB
ReStructuredText
2364 lines
90 KiB
ReStructuredText
****************************
|
||
What's New In Python 3.10
|
||
****************************
|
||
|
||
:Editor: Pablo Galindo Salgado
|
||
|
||
.. Rules for maintenance:
|
||
|
||
* Anyone can add text to this document. Do not spend very much time
|
||
on the wording of your changes, because your text will probably
|
||
get rewritten to some degree.
|
||
|
||
* The maintainer will go through Misc/NEWS periodically and add
|
||
changes; it's therefore more important to add your changes to
|
||
Misc/NEWS than to this file.
|
||
|
||
* This is not a complete list of every single change; completeness
|
||
is the purpose of Misc/NEWS. Some changes I consider too small
|
||
or esoteric to include. If such a change is added to the text,
|
||
I'll just remove it. (This is another reason you shouldn't spend
|
||
too much time on writing your addition.)
|
||
|
||
* If you want to draw your new text to the attention of the
|
||
maintainer, add 'XXX' to the beginning of the paragraph or
|
||
section.
|
||
|
||
* It's OK to just add a fragmentary note about a change. For
|
||
example: "XXX Describe the transmogrify() function added to the
|
||
socket module." The maintainer will research the change and
|
||
write the necessary text.
|
||
|
||
* You can comment out your additions if you like, but it's not
|
||
necessary (especially when a final release is some months away).
|
||
|
||
* Credit the author of a patch or bugfix. Just the name is
|
||
sufficient; the e-mail address isn't necessary.
|
||
|
||
* It's helpful to add the bug/patch number as a comment:
|
||
|
||
XXX Describe the transmogrify() function added to the socket
|
||
module.
|
||
(Contributed by P.Y. Developer in :issue:`12345`.)
|
||
|
||
This saves the maintainer the effort of going through the git log
|
||
when researching a change.
|
||
|
||
This article explains the new features in Python 3.10, compared to 3.9.
|
||
Python 3.10 was released on October 4, 2021.
|
||
For full details, see the :ref:`changelog <changelog>`.
|
||
|
||
Summary -- Release highlights
|
||
=============================
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||
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||
.. This section singles out the most important changes in Python 3.10.
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||
Brevity is key.
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||
|
||
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||
.. PEP-sized items next.
|
||
|
||
New syntax features:
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||
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||
* :pep:`634`, Structural Pattern Matching: Specification
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||
* :pep:`635`, Structural Pattern Matching: Motivation and Rationale
|
||
* :pep:`636`, Structural Pattern Matching: Tutorial
|
||
* :issue:`12782`, Parenthesized context managers are now officially allowed.
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||
|
||
New features in the standard library:
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||
|
||
* :pep:`618`, Add Optional Length-Checking To zip.
|
||
|
||
Interpreter improvements:
|
||
|
||
* :pep:`626`, Precise line numbers for debugging and other tools.
|
||
|
||
New typing features:
|
||
|
||
* :pep:`604`, Allow writing union types as X | Y
|
||
* :pep:`612`, Parameter Specification Variables
|
||
* :pep:`613`, Explicit Type Aliases
|
||
* :pep:`647`, User-Defined Type Guards
|
||
|
||
Important deprecations, removals or restrictions:
|
||
|
||
* :pep:`644`, Require OpenSSL 1.1.1 or newer
|
||
* :pep:`632`, Deprecate distutils module.
|
||
* :pep:`623`, Deprecate and prepare for the removal of the wstr member in PyUnicodeObject.
|
||
* :pep:`624`, Remove Py_UNICODE encoder APIs
|
||
* :pep:`597`, Add optional EncodingWarning
|
||
|
||
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||
New Features
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||
============
|
||
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||
.. _whatsnew310-pep563:
|
||
|
||
Parenthesized context managers
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||
------------------------------
|
||
|
||
Using enclosing parentheses for continuation across multiple lines
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||
in context managers is now supported. This allows formatting a long
|
||
collection of context managers in multiple lines in a similar way
|
||
as it was previously possible with import statements. For instance,
|
||
all these examples are now valid:
|
||
|
||
.. code-block:: python
|
||
|
||
with (CtxManager() as example):
|
||
...
|
||
|
||
with (
|
||
CtxManager1(),
|
||
CtxManager2()
|
||
):
|
||
...
|
||
|
||
with (CtxManager1() as example,
|
||
CtxManager2()):
|
||
...
|
||
|
||
with (CtxManager1(),
|
||
CtxManager2() as example):
|
||
...
|
||
|
||
with (
|
||
CtxManager1() as example1,
|
||
CtxManager2() as example2
|
||
):
|
||
...
|
||
|
||
it is also possible to use a trailing comma at the end of the
|
||
enclosed group:
|
||
|
||
.. code-block:: python
|
||
|
||
with (
|
||
CtxManager1() as example1,
|
||
CtxManager2() as example2,
|
||
CtxManager3() as example3,
|
||
):
|
||
...
|
||
|
||
This new syntax uses the non LL(1) capacities of the new parser.
|
||
Check :pep:`617` for more details.
|
||
|
||
(Contributed by Guido van Rossum, Pablo Galindo and Lysandros Nikolaou
|
||
in :issue:`12782` and :issue:`40334`.)
|
||
|
||
|
||
Better error messages
|
||
---------------------
|
||
|
||
SyntaxErrors
|
||
~~~~~~~~~~~~
|
||
|
||
When parsing code that contains unclosed parentheses or brackets the interpreter
|
||
now includes the location of the unclosed bracket of parentheses instead of displaying
|
||
*SyntaxError: unexpected EOF while parsing* or pointing to some incorrect location.
|
||
For instance, consider the following code (notice the unclosed '{'):
|
||
|
||
.. code-block:: python
|
||
|
||
expected = {9: 1, 18: 2, 19: 2, 27: 3, 28: 3, 29: 3, 36: 4, 37: 4,
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||
38: 4, 39: 4, 45: 5, 46: 5, 47: 5, 48: 5, 49: 5, 54: 6,
|
||
some_other_code = foo()
|
||
|
||
Previous versions of the interpreter reported confusing places as the location of
|
||
the syntax error:
|
||
|
||
.. code-block:: python
|
||
|
||
File "example.py", line 3
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||
some_other_code = foo()
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||
^
|
||
SyntaxError: invalid syntax
|
||
|
||
but in Python 3.10 a more informative error is emitted:
|
||
|
||
.. code-block:: python
|
||
|
||
File "example.py", line 1
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||
expected = {9: 1, 18: 2, 19: 2, 27: 3, 28: 3, 29: 3, 36: 4, 37: 4,
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||
^
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||
SyntaxError: '{' was never closed
|
||
|
||
|
||
In a similar way, errors involving unclosed string literals (single and triple
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||
quoted) now point to the start of the string instead of reporting EOF/EOL.
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||
|
||
These improvements are inspired by previous work in the PyPy interpreter.
|
||
|
||
(Contributed by Pablo Galindo in :issue:`42864` and Batuhan Taskaya in
|
||
:issue:`40176`.)
|
||
|
||
:exc:`SyntaxError` exceptions raised by the interpreter will now highlight the
|
||
full error range of the expression that constitutes the syntax error itself,
|
||
instead of just where the problem is detected. In this way, instead of displaying
|
||
(before Python 3.10):
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||
|
||
.. code-block:: python
|
||
|
||
>>> foo(x, z for z in range(10), t, w)
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||
File "<stdin>", line 1
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||
foo(x, z for z in range(10), t, w)
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||
^
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||
SyntaxError: Generator expression must be parenthesized
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||
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||
now Python 3.10 will display the exception as:
|
||
|
||
.. code-block:: python
|
||
|
||
>>> foo(x, z for z in range(10), t, w)
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||
File "<stdin>", line 1
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||
foo(x, z for z in range(10), t, w)
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||
^^^^^^^^^^^^^^^^^^^^
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||
SyntaxError: Generator expression must be parenthesized
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||
|
||
This improvement was contributed by Pablo Galindo in :issue:`43914`.
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||
|
||
A considerable amount of new specialized messages for :exc:`SyntaxError` exceptions
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||
have been incorporated. Some of the most notable ones are as follows:
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||
|
||
* Missing ``:`` before blocks:
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||
|
||
.. code-block:: python
|
||
|
||
>>> if rocket.position > event_horizon
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||
File "<stdin>", line 1
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||
if rocket.position > event_horizon
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||
^
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||
SyntaxError: expected ':'
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||
|
||
(Contributed by Pablo Galindo in :issue:`42997`.)
|
||
|
||
* Unparenthesised tuples in comprehensions targets:
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||
|
||
.. code-block:: python
|
||
|
||
>>> {x,y for x,y in zip('abcd', '1234')}
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||
File "<stdin>", line 1
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||
{x,y for x,y in zip('abcd', '1234')}
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||
^
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||
SyntaxError: did you forget parentheses around the comprehension target?
|
||
|
||
(Contributed by Pablo Galindo in :issue:`43017`.)
|
||
|
||
* Missing commas in collection literals and between expressions:
|
||
|
||
.. code-block:: python
|
||
|
||
>>> items = {
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||
... x: 1,
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||
... y: 2
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||
... z: 3,
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File "<stdin>", line 3
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y: 2
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||
^
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||
SyntaxError: invalid syntax. Perhaps you forgot a comma?
|
||
|
||
(Contributed by Pablo Galindo in :issue:`43822`.)
|
||
|
||
* Multiple Exception types without parentheses:
|
||
|
||
.. code-block:: python
|
||
|
||
>>> try:
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||
... build_dyson_sphere()
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||
... except NotEnoughScienceError, NotEnoughResourcesError:
|
||
File "<stdin>", line 3
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||
except NotEnoughScienceError, NotEnoughResourcesError:
|
||
^
|
||
SyntaxError: multiple exception types must be parenthesized
|
||
|
||
(Contributed by Pablo Galindo in :issue:`43149`.)
|
||
|
||
* Missing ``:`` and values in dictionary literals:
|
||
|
||
.. code-block:: python
|
||
|
||
>>> values = {
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||
... x: 1,
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||
... y: 2,
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||
... z:
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||
... }
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||
File "<stdin>", line 4
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||
z:
|
||
^
|
||
SyntaxError: expression expected after dictionary key and ':'
|
||
|
||
>>> values = {x:1, y:2, z w:3}
|
||
File "<stdin>", line 1
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||
values = {x:1, y:2, z w:3}
|
||
^
|
||
SyntaxError: ':' expected after dictionary key
|
||
|
||
(Contributed by Pablo Galindo in :issue:`43823`.)
|
||
|
||
* ``try`` blocks without ``except`` or ``finally`` blocks:
|
||
|
||
.. code-block:: python
|
||
|
||
>>> try:
|
||
... x = 2
|
||
... something = 3
|
||
File "<stdin>", line 3
|
||
something = 3
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||
^^^^^^^^^
|
||
SyntaxError: expected 'except' or 'finally' block
|
||
|
||
(Contributed by Pablo Galindo in :issue:`44305`.)
|
||
|
||
* Usage of ``=`` instead of ``==`` in comparisons:
|
||
|
||
.. code-block:: python
|
||
|
||
>>> if rocket.position = event_horizon:
|
||
File "<stdin>", line 1
|
||
if rocket.position = event_horizon:
|
||
^
|
||
SyntaxError: cannot assign to attribute here. Maybe you meant '==' instead of '='?
|
||
|
||
(Contributed by Pablo Galindo in :issue:`43797`.)
|
||
|
||
* Usage of ``*`` in f-strings:
|
||
|
||
.. code-block:: python
|
||
|
||
>>> f"Black holes {*all_black_holes} and revelations"
|
||
File "<stdin>", line 1
|
||
(*all_black_holes)
|
||
^
|
||
SyntaxError: f-string: cannot use starred expression here
|
||
|
||
(Contributed by Pablo Galindo in :issue:`41064`.)
|
||
|
||
IndentationErrors
|
||
~~~~~~~~~~~~~~~~~
|
||
|
||
Many :exc:`IndentationError` exceptions now have more context regarding what kind of block
|
||
was expecting an indentation, including the location of the statement:
|
||
|
||
.. code-block:: python
|
||
|
||
>>> def foo():
|
||
... if lel:
|
||
... x = 2
|
||
File "<stdin>", line 3
|
||
x = 2
|
||
^
|
||
IndentationError: expected an indented block after 'if' statement in line 2
|
||
|
||
|
||
AttributeErrors
|
||
~~~~~~~~~~~~~~~
|
||
|
||
When printing :exc:`AttributeError`, :c:func:`!PyErr_Display` will offer
|
||
suggestions of similar attribute names in the object that the exception was
|
||
raised from:
|
||
|
||
.. code-block:: python
|
||
|
||
>>> collections.namedtoplo
|
||
Traceback (most recent call last):
|
||
File "<stdin>", line 1, in <module>
|
||
AttributeError: module 'collections' has no attribute 'namedtoplo'. Did you mean: namedtuple?
|
||
|
||
(Contributed by Pablo Galindo in :issue:`38530`.)
|
||
|
||
.. warning::
|
||
Notice this won't work if :c:func:`!PyErr_Display` is not called to display the error
|
||
which can happen if some other custom error display function is used. This is a common
|
||
scenario in some REPLs like IPython.
|
||
|
||
NameErrors
|
||
~~~~~~~~~~
|
||
|
||
When printing :exc:`NameError` raised by the interpreter, :c:func:`!PyErr_Display`
|
||
will offer suggestions of similar variable names in the function that the exception
|
||
was raised from:
|
||
|
||
.. code-block:: python
|
||
|
||
>>> schwarzschild_black_hole = None
|
||
>>> schwarschild_black_hole
|
||
Traceback (most recent call last):
|
||
File "<stdin>", line 1, in <module>
|
||
NameError: name 'schwarschild_black_hole' is not defined. Did you mean: schwarzschild_black_hole?
|
||
|
||
(Contributed by Pablo Galindo in :issue:`38530`.)
|
||
|
||
.. warning::
|
||
Notice this won't work if :c:func:`!PyErr_Display` is not called to display the error,
|
||
which can happen if some other custom error display function is used. This is a common
|
||
scenario in some REPLs like IPython.
|
||
|
||
|
||
PEP 626: Precise line numbers for debugging and other tools
|
||
-----------------------------------------------------------
|
||
|
||
PEP 626 brings more precise and reliable line numbers for debugging, profiling and coverage tools.
|
||
Tracing events, with the correct line number, are generated for all lines of code executed and only for lines of code that are executed.
|
||
|
||
The :attr:`~frame.f_lineno` attribute of frame objects will always contain the
|
||
expected line number.
|
||
|
||
The :attr:`~codeobject.co_lnotab` attribute of
|
||
:ref:`code objects <code-objects>` is deprecated and
|
||
will be removed in 3.12.
|
||
Code that needs to convert from offset to line number should use the new
|
||
:meth:`~codeobject.co_lines` method instead.
|
||
|
||
PEP 634: Structural Pattern Matching
|
||
------------------------------------
|
||
|
||
Structural pattern matching has been added in the form of a *match statement*
|
||
and *case statements* of patterns with associated actions. Patterns
|
||
consist of sequences, mappings, primitive data types as well as class instances.
|
||
Pattern matching enables programs to extract information from complex data types,
|
||
branch on the structure of data, and apply specific actions based on different
|
||
forms of data.
|
||
|
||
Syntax and operations
|
||
~~~~~~~~~~~~~~~~~~~~~
|
||
|
||
The generic syntax of pattern matching is::
|
||
|
||
match subject:
|
||
case <pattern_1>:
|
||
<action_1>
|
||
case <pattern_2>:
|
||
<action_2>
|
||
case <pattern_3>:
|
||
<action_3>
|
||
case _:
|
||
<action_wildcard>
|
||
|
||
A match statement takes an expression and compares its value to successive
|
||
patterns given as one or more case blocks. Specifically, pattern matching
|
||
operates by:
|
||
|
||
1. using data with type and shape (the ``subject``)
|
||
2. evaluating the ``subject`` in the ``match`` statement
|
||
3. comparing the subject with each pattern in a ``case`` statement
|
||
from top to bottom until a match is confirmed.
|
||
4. executing the action associated with the pattern of the confirmed
|
||
match
|
||
5. If an exact match is not confirmed, the last case, a wildcard ``_``,
|
||
if provided, will be used as the matching case. If an exact match is
|
||
not confirmed and a wildcard case does not exist, the entire match
|
||
block is a no-op.
|
||
|
||
Declarative approach
|
||
~~~~~~~~~~~~~~~~~~~~
|
||
|
||
Readers may be aware of pattern matching through the simple example of matching
|
||
a subject (data object) to a literal (pattern) with the switch statement found
|
||
in C, Java or JavaScript (and many other languages). Often the switch statement
|
||
is used for comparison of an object/expression with case statements containing
|
||
literals.
|
||
|
||
More powerful examples of pattern matching can be found in languages such as
|
||
Scala and Elixir. With structural pattern matching, the approach is "declarative" and
|
||
explicitly states the conditions (the patterns) for data to match.
|
||
|
||
While an "imperative" series of instructions using nested "if" statements
|
||
could be used to accomplish something similar to structural pattern matching,
|
||
it is less clear than the "declarative" approach. Instead the "declarative"
|
||
approach states the conditions to meet for a match and is more readable through
|
||
its explicit patterns. While structural pattern matching can be used in its
|
||
simplest form comparing a variable to a literal in a case statement, its
|
||
true value for Python lies in its handling of the subject's type and shape.
|
||
|
||
Simple pattern: match to a literal
|
||
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
||
|
||
Let's look at this example as pattern matching in its simplest form: a value,
|
||
the subject, being matched to several literals, the patterns. In the example
|
||
below, ``status`` is the subject of the match statement. The patterns are
|
||
each of the case statements, where literals represent request status codes.
|
||
The associated action to the case is executed after a match::
|
||
|
||
def http_error(status):
|
||
match status:
|
||
case 400:
|
||
return "Bad request"
|
||
case 404:
|
||
return "Not found"
|
||
case 418:
|
||
return "I'm a teapot"
|
||
case _:
|
||
return "Something's wrong with the internet"
|
||
|
||
If the above function is passed a ``status`` of 418, "I'm a teapot" is returned.
|
||
If the above function is passed a ``status`` of 500, the case statement with
|
||
``_`` will match as a wildcard, and "Something's wrong with the internet" is
|
||
returned.
|
||
Note the last block: the variable name, ``_``, acts as a *wildcard* and insures
|
||
the subject will always match. The use of ``_`` is optional.
|
||
|
||
You can combine several literals in a single pattern using ``|`` ("or")::
|
||
|
||
case 401 | 403 | 404:
|
||
return "Not allowed"
|
||
|
||
Behavior without the wildcard
|
||
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||
|
||
If we modify the above example by removing the last case block, the example
|
||
becomes::
|
||
|
||
def http_error(status):
|
||
match status:
|
||
case 400:
|
||
return "Bad request"
|
||
case 404:
|
||
return "Not found"
|
||
case 418:
|
||
return "I'm a teapot"
|
||
|
||
Without the use of ``_`` in a case statement, a match may not exist. If no
|
||
match exists, the behavior is a no-op. For example, if ``status`` of 500 is
|
||
passed, a no-op occurs.
|
||
|
||
Patterns with a literal and variable
|
||
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
||
|
||
Patterns can look like unpacking assignments, and a pattern may be used to bind
|
||
variables. In this example, a data point can be unpacked to its x-coordinate
|
||
and y-coordinate::
|
||
|
||
# point is an (x, y) tuple
|
||
match point:
|
||
case (0, 0):
|
||
print("Origin")
|
||
case (0, y):
|
||
print(f"Y={y}")
|
||
case (x, 0):
|
||
print(f"X={x}")
|
||
case (x, y):
|
||
print(f"X={x}, Y={y}")
|
||
case _:
|
||
raise ValueError("Not a point")
|
||
|
||
The first pattern has two literals, ``(0, 0)``, and may be thought of as an
|
||
extension of the literal pattern shown above. The next two patterns combine a
|
||
literal and a variable, and the variable *binds* a value from the subject
|
||
(``point``). The fourth pattern captures two values, which makes it
|
||
conceptually similar to the unpacking assignment ``(x, y) = point``.
|
||
|
||
Patterns and classes
|
||
~~~~~~~~~~~~~~~~~~~~
|
||
|
||
If you are using classes to structure your data, you can use as a pattern
|
||
the class name followed by an argument list resembling a constructor. This
|
||
pattern has the ability to capture class attributes into variables::
|
||
|
||
class Point:
|
||
x: int
|
||
y: int
|
||
|
||
def location(point):
|
||
match point:
|
||
case Point(x=0, y=0):
|
||
print("Origin is the point's location.")
|
||
case Point(x=0, y=y):
|
||
print(f"Y={y} and the point is on the y-axis.")
|
||
case Point(x=x, y=0):
|
||
print(f"X={x} and the point is on the x-axis.")
|
||
case Point():
|
||
print("The point is located somewhere else on the plane.")
|
||
case _:
|
||
print("Not a point")
|
||
|
||
Patterns with positional parameters
|
||
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||
|
||
You can use positional parameters with some builtin classes that provide an
|
||
ordering for their attributes (e.g. dataclasses). You can also define a specific
|
||
position for attributes in patterns by setting the ``__match_args__`` special
|
||
attribute in your classes. If it's set to ("x", "y"), the following patterns
|
||
are all equivalent (and all bind the ``y`` attribute to the ``var`` variable)::
|
||
|
||
Point(1, var)
|
||
Point(1, y=var)
|
||
Point(x=1, y=var)
|
||
Point(y=var, x=1)
|
||
|
||
Nested patterns
|
||
~~~~~~~~~~~~~~~
|
||
|
||
Patterns can be arbitrarily nested. For example, if our data is a short
|
||
list of points, it could be matched like this::
|
||
|
||
match points:
|
||
case []:
|
||
print("No points in the list.")
|
||
case [Point(0, 0)]:
|
||
print("The origin is the only point in the list.")
|
||
case [Point(x, y)]:
|
||
print(f"A single point {x}, {y} is in the list.")
|
||
case [Point(0, y1), Point(0, y2)]:
|
||
print(f"Two points on the Y axis at {y1}, {y2} are in the list.")
|
||
case _:
|
||
print("Something else is found in the list.")
|
||
|
||
Complex patterns and the wildcard
|
||
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
||
|
||
To this point, the examples have used ``_`` alone in the last case statement.
|
||
A wildcard can be used in more complex patterns, such as ``('error', code, _)``.
|
||
For example::
|
||
|
||
match test_variable:
|
||
case ('warning', code, 40):
|
||
print("A warning has been received.")
|
||
case ('error', code, _):
|
||
print(f"An error {code} occurred.")
|
||
|
||
In the above case, ``test_variable`` will match for ('error', code, 100) and
|
||
('error', code, 800).
|
||
|
||
Guard
|
||
~~~~~
|
||
|
||
We can add an ``if`` clause to a pattern, known as a "guard". If the
|
||
guard is false, ``match`` goes on to try the next case block. Note
|
||
that value capture happens before the guard is evaluated::
|
||
|
||
match point:
|
||
case Point(x, y) if x == y:
|
||
print(f"The point is located on the diagonal Y=X at {x}.")
|
||
case Point(x, y):
|
||
print(f"Point is not on the diagonal.")
|
||
|
||
Other Key Features
|
||
~~~~~~~~~~~~~~~~~~
|
||
|
||
Several other key features:
|
||
|
||
- Like unpacking assignments, tuple and list patterns have exactly the
|
||
same meaning and actually match arbitrary sequences. Technically,
|
||
the subject must be a sequence.
|
||
Therefore, an important exception is that patterns don't match iterators.
|
||
Also, to prevent a common mistake, sequence patterns don't match strings.
|
||
|
||
- Sequence patterns support wildcards: ``[x, y, *rest]`` and ``(x, y,
|
||
*rest)`` work similar to wildcards in unpacking assignments. The
|
||
name after ``*`` may also be ``_``, so ``(x, y, *_)`` matches a sequence
|
||
of at least two items without binding the remaining items.
|
||
|
||
- Mapping patterns: ``{"bandwidth": b, "latency": l}`` captures the
|
||
``"bandwidth"`` and ``"latency"`` values from a dict. Unlike sequence
|
||
patterns, extra keys are ignored. A wildcard ``**rest`` is also
|
||
supported. (But ``**_`` would be redundant, so is not allowed.)
|
||
|
||
- Subpatterns may be captured using the ``as`` keyword::
|
||
|
||
case (Point(x1, y1), Point(x2, y2) as p2): ...
|
||
|
||
This binds x1, y1, x2, y2 like you would expect without the ``as`` clause,
|
||
and p2 to the entire second item of the subject.
|
||
|
||
- Most literals are compared by equality. However, the singletons ``True``,
|
||
``False`` and ``None`` are compared by identity.
|
||
|
||
- Named constants may be used in patterns. These named constants must be
|
||
dotted names to prevent the constant from being interpreted as a capture
|
||
variable::
|
||
|
||
from enum import Enum
|
||
class Color(Enum):
|
||
RED = 0
|
||
GREEN = 1
|
||
BLUE = 2
|
||
|
||
color = Color.GREEN
|
||
match color:
|
||
case Color.RED:
|
||
print("I see red!")
|
||
case Color.GREEN:
|
||
print("Grass is green")
|
||
case Color.BLUE:
|
||
print("I'm feeling the blues :(")
|
||
|
||
For the full specification see :pep:`634`. Motivation and rationale
|
||
are in :pep:`635`, and a longer tutorial is in :pep:`636`.
|
||
|
||
|
||
.. _whatsnew310-pep597:
|
||
|
||
Optional ``EncodingWarning`` and ``encoding="locale"`` option
|
||
-------------------------------------------------------------
|
||
|
||
The default encoding of :class:`~io.TextIOWrapper` and :func:`open` is
|
||
platform and locale dependent. Since UTF-8 is used on most Unix
|
||
platforms, omitting ``encoding`` option when opening UTF-8 files
|
||
(e.g. JSON, YAML, TOML, Markdown) is a very common bug. For example::
|
||
|
||
# BUG: "rb" mode or encoding="utf-8" should be used.
|
||
with open("data.json") as f:
|
||
data = json.load(f)
|
||
|
||
To find this type of bug, an optional ``EncodingWarning`` is added.
|
||
It is emitted when :data:`sys.flags.warn_default_encoding <sys.flags>`
|
||
is true and locale-specific default encoding is used.
|
||
|
||
``-X warn_default_encoding`` option and :envvar:`PYTHONWARNDEFAULTENCODING`
|
||
are added to enable the warning.
|
||
|
||
See :ref:`io-text-encoding` for more information.
|
||
|
||
.. _new-feat-related-type-hints:
|
||
|
||
New Features Related to Type Hints
|
||
==================================
|
||
|
||
This section covers major changes affecting :pep:`484` type hints and
|
||
the :mod:`typing` module.
|
||
|
||
|
||
PEP 604: New Type Union Operator
|
||
--------------------------------
|
||
|
||
A new type union operator was introduced which enables the syntax ``X | Y``.
|
||
This provides a cleaner way of expressing 'either type X or type Y' instead of
|
||
using :data:`typing.Union`, especially in type hints.
|
||
|
||
In previous versions of Python, to apply a type hint for functions accepting
|
||
arguments of multiple types, :data:`typing.Union` was used::
|
||
|
||
def square(number: Union[int, float]) -> Union[int, float]:
|
||
return number ** 2
|
||
|
||
|
||
Type hints can now be written in a more succinct manner::
|
||
|
||
def square(number: int | float) -> int | float:
|
||
return number ** 2
|
||
|
||
|
||
This new syntax is also accepted as the second argument to :func:`isinstance`
|
||
and :func:`issubclass`::
|
||
|
||
>>> isinstance(1, int | str)
|
||
True
|
||
|
||
See :ref:`types-union` and :pep:`604` for more details.
|
||
|
||
(Contributed by Maggie Moss and Philippe Prados in :issue:`41428`,
|
||
with additions by Yurii Karabas and Serhiy Storchaka in :issue:`44490`.)
|
||
|
||
|
||
PEP 612: Parameter Specification Variables
|
||
------------------------------------------
|
||
|
||
Two new options to improve the information provided to static type checkers for
|
||
:pep:`484`\ 's ``Callable`` have been added to the :mod:`typing` module.
|
||
|
||
The first is the parameter specification variable. They are used to forward the
|
||
parameter types of one callable to another callable -- a pattern commonly
|
||
found in higher order functions and decorators. Examples of usage can be found
|
||
in :class:`typing.ParamSpec`. Previously, there was no easy way to type annotate
|
||
dependency of parameter types in such a precise manner.
|
||
|
||
The second option is the new ``Concatenate`` operator. It's used in conjunction
|
||
with parameter specification variables to type annotate a higher order callable
|
||
which adds or removes parameters of another callable. Examples of usage can
|
||
be found in :class:`typing.Concatenate`.
|
||
|
||
See :class:`typing.Callable`, :class:`typing.ParamSpec`,
|
||
:class:`typing.Concatenate`, :class:`typing.ParamSpecArgs`,
|
||
:class:`typing.ParamSpecKwargs`, and :pep:`612` for more details.
|
||
|
||
(Contributed by Ken Jin in :issue:`41559`, with minor enhancements by Jelle
|
||
Zijlstra in :issue:`43783`. PEP written by Mark Mendoza.)
|
||
|
||
|
||
PEP 613: TypeAlias
|
||
------------------
|
||
|
||
:pep:`484` introduced the concept of type aliases, only requiring them to be
|
||
top-level unannotated assignments. This simplicity sometimes made it difficult
|
||
for type checkers to distinguish between type aliases and ordinary assignments,
|
||
especially when forward references or invalid types were involved. Compare::
|
||
|
||
StrCache = 'Cache[str]' # a type alias
|
||
LOG_PREFIX = 'LOG[DEBUG]' # a module constant
|
||
|
||
Now the :mod:`typing` module has a special value :data:`~typing.TypeAlias`
|
||
which lets you declare type aliases more explicitly::
|
||
|
||
StrCache: TypeAlias = 'Cache[str]' # a type alias
|
||
LOG_PREFIX = 'LOG[DEBUG]' # a module constant
|
||
|
||
See :pep:`613` for more details.
|
||
|
||
(Contributed by Mikhail Golubev in :issue:`41923`.)
|
||
|
||
PEP 647: User-Defined Type Guards
|
||
---------------------------------
|
||
|
||
:data:`~typing.TypeGuard` has been added to the :mod:`typing` module to annotate
|
||
type guard functions and improve information provided to static type checkers
|
||
during type narrowing. For more information, please see
|
||
:data:`~typing.TypeGuard`\ 's documentation, and :pep:`647`.
|
||
|
||
(Contributed by Ken Jin and Guido van Rossum in :issue:`43766`.
|
||
PEP written by Eric Traut.)
|
||
|
||
Other Language Changes
|
||
======================
|
||
|
||
* The :class:`int` type has a new method :meth:`int.bit_count`, returning the
|
||
number of ones in the binary expansion of a given integer, also known
|
||
as the population count. (Contributed by Niklas Fiekas in :issue:`29882`.)
|
||
|
||
* The views returned by :meth:`dict.keys`, :meth:`dict.values` and
|
||
:meth:`dict.items` now all have a ``mapping`` attribute that gives a
|
||
:class:`types.MappingProxyType` object wrapping the original
|
||
dictionary. (Contributed by Dennis Sweeney in :issue:`40890`.)
|
||
|
||
* :pep:`618`: The :func:`zip` function now has an optional ``strict`` flag, used
|
||
to require that all the iterables have an equal length.
|
||
|
||
* Builtin and extension functions that take integer arguments no longer accept
|
||
:class:`~decimal.Decimal`\ s, :class:`~fractions.Fraction`\ s and other
|
||
objects that can be converted to integers only with a loss (e.g. that have
|
||
the :meth:`~object.__int__` method but do not have the
|
||
:meth:`~object.__index__` method).
|
||
(Contributed by Serhiy Storchaka in :issue:`37999`.)
|
||
|
||
* If :func:`object.__ipow__` returns :data:`NotImplemented`, the operator will
|
||
correctly fall back to :func:`object.__pow__` and :func:`object.__rpow__` as expected.
|
||
(Contributed by Alex Shkop in :issue:`38302`.)
|
||
|
||
* Assignment expressions can now be used unparenthesized within set literals
|
||
and set comprehensions, as well as in sequence indexes (but not slices).
|
||
|
||
* Functions have a new ``__builtins__`` attribute which is used to look for
|
||
builtin symbols when a function is executed, instead of looking into
|
||
``__globals__['__builtins__']``. The attribute is initialized from
|
||
``__globals__["__builtins__"]`` if it exists, else from the current builtins.
|
||
(Contributed by Mark Shannon in :issue:`42990`.)
|
||
|
||
* Two new builtin functions -- :func:`aiter` and :func:`anext` have been added
|
||
to provide asynchronous counterparts to :func:`iter` and :func:`next`,
|
||
respectively.
|
||
(Contributed by Joshua Bronson, Daniel Pope, and Justin Wang in :issue:`31861`.)
|
||
|
||
* Static methods (:func:`@staticmethod <staticmethod>`) and class methods
|
||
(:func:`@classmethod <classmethod>`) now inherit the method attributes
|
||
(``__module__``, ``__name__``, ``__qualname__``, ``__doc__``,
|
||
``__annotations__``) and have a new ``__wrapped__`` attribute.
|
||
Moreover, static methods are now callable as regular functions.
|
||
(Contributed by Victor Stinner in :issue:`43682`.)
|
||
|
||
* Annotations for complex targets (everything beside ``simple name`` targets
|
||
defined by :pep:`526`) no longer cause any runtime effects with ``from __future__ import annotations``.
|
||
(Contributed by Batuhan Taskaya in :issue:`42737`.)
|
||
|
||
* Class and module objects now lazy-create empty annotations dicts on demand.
|
||
The annotations dicts are stored in the object’s ``__dict__`` for
|
||
backwards compatibility. This improves the best practices for working
|
||
with ``__annotations__``; for more information, please see
|
||
:ref:`annotations-howto`.
|
||
(Contributed by Larry Hastings in :issue:`43901`.)
|
||
|
||
* Annotations consist of ``yield``, ``yield from``, ``await`` or named expressions
|
||
are now forbidden under ``from __future__ import annotations`` due to their side
|
||
effects.
|
||
(Contributed by Batuhan Taskaya in :issue:`42725`.)
|
||
|
||
* Usage of unbound variables, ``super()`` and other expressions that might
|
||
alter the processing of symbol table as annotations are now rendered
|
||
effectless under ``from __future__ import annotations``.
|
||
(Contributed by Batuhan Taskaya in :issue:`42725`.)
|
||
|
||
* Hashes of NaN values of both :class:`float` type and
|
||
:class:`decimal.Decimal` type now depend on object identity. Formerly, they
|
||
always hashed to ``0`` even though NaN values are not equal to one another.
|
||
This caused potentially quadratic runtime behavior due to excessive hash
|
||
collisions when creating dictionaries and sets containing multiple NaNs.
|
||
(Contributed by Raymond Hettinger in :issue:`43475`.)
|
||
|
||
* A :exc:`SyntaxError` (instead of a :exc:`NameError`) will be raised when deleting
|
||
the :const:`__debug__` constant. (Contributed by Donghee Na in :issue:`45000`.)
|
||
|
||
* :exc:`SyntaxError` exceptions now have ``end_lineno`` and
|
||
``end_offset`` attributes. They will be ``None`` if not determined.
|
||
(Contributed by Pablo Galindo in :issue:`43914`.)
|
||
|
||
New Modules
|
||
===========
|
||
|
||
* None.
|
||
|
||
|
||
Improved Modules
|
||
================
|
||
|
||
asyncio
|
||
-------
|
||
|
||
Add missing :meth:`~asyncio.events.AbstractEventLoop.connect_accepted_socket`
|
||
method.
|
||
(Contributed by Alex Grönholm in :issue:`41332`.)
|
||
|
||
argparse
|
||
--------
|
||
|
||
Misleading phrase "optional arguments" was replaced with "options" in argparse help. Some tests might require adaptation if they rely on exact output match.
|
||
(Contributed by Raymond Hettinger in :issue:`9694`.)
|
||
|
||
array
|
||
-----
|
||
|
||
The :meth:`~array.array.index` method of :class:`array.array` now has
|
||
optional *start* and *stop* parameters.
|
||
(Contributed by Anders Lorentsen and Zackery Spytz in :issue:`31956`.)
|
||
|
||
asynchat, asyncore, smtpd
|
||
-------------------------
|
||
These modules have been marked as deprecated in their module documentation
|
||
since Python 3.6. An import-time :class:`DeprecationWarning` has now been
|
||
added to all three of these modules.
|
||
|
||
base64
|
||
------
|
||
|
||
Add :func:`base64.b32hexencode` and :func:`base64.b32hexdecode` to support the
|
||
Base32 Encoding with Extended Hex Alphabet.
|
||
|
||
bdb
|
||
---
|
||
|
||
Add :meth:`~bdb.Breakpoint.clearBreakpoints` to reset all set breakpoints.
|
||
(Contributed by Irit Katriel in :issue:`24160`.)
|
||
|
||
bisect
|
||
------
|
||
|
||
Added the possibility of providing a *key* function to the APIs in the :mod:`bisect`
|
||
module. (Contributed by Raymond Hettinger in :issue:`4356`.)
|
||
|
||
codecs
|
||
------
|
||
|
||
Add a :func:`codecs.unregister` function to unregister a codec search function.
|
||
(Contributed by Hai Shi in :issue:`41842`.)
|
||
|
||
collections.abc
|
||
---------------
|
||
|
||
The ``__args__`` of the :ref:`parameterized generic <types-genericalias>` for
|
||
:class:`collections.abc.Callable` are now consistent with :data:`typing.Callable`.
|
||
:class:`collections.abc.Callable` generic now flattens type parameters, similar
|
||
to what :data:`typing.Callable` currently does. This means that
|
||
``collections.abc.Callable[[int, str], str]`` will have ``__args__`` of
|
||
``(int, str, str)``; previously this was ``([int, str], str)``. To allow this
|
||
change, :class:`types.GenericAlias` can now be subclassed, and a subclass will
|
||
be returned when subscripting the :class:`collections.abc.Callable` type. Note
|
||
that a :exc:`TypeError` may be raised for invalid forms of parameterizing
|
||
:class:`collections.abc.Callable` which may have passed silently in Python 3.9.
|
||
(Contributed by Ken Jin in :issue:`42195`.)
|
||
|
||
contextlib
|
||
----------
|
||
|
||
Add a :func:`contextlib.aclosing` context manager to safely close async generators
|
||
and objects representing asynchronously released resources.
|
||
(Contributed by Joongi Kim and John Belmonte in :issue:`41229`.)
|
||
|
||
Add asynchronous context manager support to :func:`contextlib.nullcontext`.
|
||
(Contributed by Tom Gringauz in :issue:`41543`.)
|
||
|
||
Add :class:`~contextlib.AsyncContextDecorator`, for supporting usage of async
|
||
context managers as decorators.
|
||
|
||
curses
|
||
------
|
||
|
||
The extended color functions added in ncurses 6.1 will be used transparently
|
||
by :func:`curses.color_content`, :func:`curses.init_color`,
|
||
:func:`curses.init_pair`, and :func:`curses.pair_content`. A new function,
|
||
:func:`curses.has_extended_color_support`, indicates whether extended color
|
||
support is provided by the underlying ncurses library.
|
||
(Contributed by Jeffrey Kintscher and Hans Petter Jansson in :issue:`36982`.)
|
||
|
||
The ``BUTTON5_*`` constants are now exposed in the :mod:`curses` module if
|
||
they are provided by the underlying curses library.
|
||
(Contributed by Zackery Spytz in :issue:`39273`.)
|
||
|
||
dataclasses
|
||
-----------
|
||
|
||
__slots__
|
||
~~~~~~~~~
|
||
|
||
Added ``slots`` parameter in :func:`dataclasses.dataclass` decorator.
|
||
(Contributed by Yurii Karabas in :issue:`42269`)
|
||
|
||
Keyword-only fields
|
||
~~~~~~~~~~~~~~~~~~~
|
||
|
||
dataclasses now supports fields that are keyword-only in the
|
||
generated __init__ method. There are a number of ways of specifying
|
||
keyword-only fields.
|
||
|
||
You can say that every field is keyword-only:
|
||
|
||
.. code-block:: python
|
||
|
||
from dataclasses import dataclass
|
||
|
||
@dataclass(kw_only=True)
|
||
class Birthday:
|
||
name: str
|
||
birthday: datetime.date
|
||
|
||
Both ``name`` and ``birthday`` are keyword-only parameters to the
|
||
generated __init__ method.
|
||
|
||
You can specify keyword-only on a per-field basis:
|
||
|
||
.. code-block:: python
|
||
|
||
from dataclasses import dataclass, field
|
||
|
||
@dataclass
|
||
class Birthday:
|
||
name: str
|
||
birthday: datetime.date = field(kw_only=True)
|
||
|
||
Here only ``birthday`` is keyword-only. If you set ``kw_only`` on
|
||
individual fields, be aware that there are rules about re-ordering
|
||
fields due to keyword-only fields needing to follow non-keyword-only
|
||
fields. See the full dataclasses documentation for details.
|
||
|
||
You can also specify that all fields following a KW_ONLY marker are
|
||
keyword-only. This will probably be the most common usage:
|
||
|
||
.. code-block:: python
|
||
|
||
from dataclasses import dataclass, KW_ONLY
|
||
|
||
@dataclass
|
||
class Point:
|
||
x: float
|
||
y: float
|
||
_: KW_ONLY
|
||
z: float = 0.0
|
||
t: float = 0.0
|
||
|
||
Here, ``z`` and ``t`` are keyword-only parameters, while ``x`` and
|
||
``y`` are not.
|
||
(Contributed by Eric V. Smith in :issue:`43532`.)
|
||
|
||
.. _distutils-deprecated:
|
||
|
||
distutils
|
||
---------
|
||
|
||
The entire ``distutils`` package is deprecated, to be removed in Python
|
||
3.12. Its functionality for specifying package builds has already been
|
||
completely replaced by third-party packages ``setuptools`` and
|
||
``packaging``, and most other commonly used APIs are available elsewhere
|
||
in the standard library (such as :mod:`platform`, :mod:`shutil`,
|
||
:mod:`subprocess` or :mod:`sysconfig`). There are no plans to migrate
|
||
any other functionality from ``distutils``, and applications that are
|
||
using other functions should plan to make private copies of the code.
|
||
Refer to :pep:`632` for discussion.
|
||
|
||
The ``bdist_wininst`` command deprecated in Python 3.8 has been removed.
|
||
The ``bdist_wheel`` command is now recommended to distribute binary packages
|
||
on Windows.
|
||
(Contributed by Victor Stinner in :issue:`42802`.)
|
||
|
||
doctest
|
||
-------
|
||
|
||
When a module does not define ``__loader__``, fall back to ``__spec__.loader``.
|
||
(Contributed by Brett Cannon in :issue:`42133`.)
|
||
|
||
encodings
|
||
---------
|
||
|
||
:func:`encodings.normalize_encoding` now ignores non-ASCII characters.
|
||
(Contributed by Hai Shi in :issue:`39337`.)
|
||
|
||
enum
|
||
----
|
||
|
||
:class:`~enum.Enum` :func:`~object.__repr__` now returns ``enum_name.member_name`` and
|
||
:func:`~object.__str__` now returns ``member_name``. Stdlib enums available as
|
||
module constants have a :func:`repr` of ``module_name.member_name``.
|
||
(Contributed by Ethan Furman in :issue:`40066`.)
|
||
|
||
Add :class:`enum.StrEnum` for enums where all members are strings.
|
||
(Contributed by Ethan Furman in :issue:`41816`.)
|
||
|
||
fileinput
|
||
---------
|
||
|
||
Add *encoding* and *errors* parameters in :func:`fileinput.input` and
|
||
:class:`fileinput.FileInput`.
|
||
(Contributed by Inada Naoki in :issue:`43712`.)
|
||
|
||
:func:`fileinput.hook_compressed` now returns :class:`~io.TextIOWrapper` object
|
||
when *mode* is "r" and file is compressed, like uncompressed files.
|
||
(Contributed by Inada Naoki in :issue:`5758`.)
|
||
|
||
faulthandler
|
||
------------
|
||
|
||
The :mod:`faulthandler` module now detects if a fatal error occurs during a
|
||
garbage collector collection.
|
||
(Contributed by Victor Stinner in :issue:`44466`.)
|
||
|
||
gc
|
||
--
|
||
|
||
Add audit hooks for :func:`gc.get_objects`, :func:`gc.get_referrers` and
|
||
:func:`gc.get_referents`. (Contributed by Pablo Galindo in :issue:`43439`.)
|
||
|
||
glob
|
||
----
|
||
|
||
Add the *root_dir* and *dir_fd* parameters in :func:`~glob.glob` and
|
||
:func:`~glob.iglob` which allow to specify the root directory for searching.
|
||
(Contributed by Serhiy Storchaka in :issue:`38144`.)
|
||
|
||
hashlib
|
||
-------
|
||
|
||
The hashlib module requires OpenSSL 1.1.1 or newer.
|
||
(Contributed by Christian Heimes in :pep:`644` and :issue:`43669`.)
|
||
|
||
The hashlib module has preliminary support for OpenSSL 3.0.0.
|
||
(Contributed by Christian Heimes in :issue:`38820` and other issues.)
|
||
|
||
The pure-Python fallback of :func:`~hashlib.pbkdf2_hmac` is deprecated. In
|
||
the future PBKDF2-HMAC will only be available when Python has been built with
|
||
OpenSSL support.
|
||
(Contributed by Christian Heimes in :issue:`43880`.)
|
||
|
||
hmac
|
||
----
|
||
|
||
The hmac module now uses OpenSSL's HMAC implementation internally.
|
||
(Contributed by Christian Heimes in :issue:`40645`.)
|
||
|
||
IDLE and idlelib
|
||
----------------
|
||
|
||
Make IDLE invoke :func:`sys.excepthook` (when started without '-n').
|
||
User hooks were previously ignored. (Contributed by Ken Hilton in
|
||
:issue:`43008`.)
|
||
|
||
Rearrange the settings dialog. Split the General tab into Windows
|
||
and Shell/Ed tabs. Move help sources, which extend the Help menu, to the
|
||
Extensions tab. Make space for new options and shorten the dialog. The
|
||
latter makes the dialog better fit small screens. (Contributed by Terry Jan
|
||
Reedy in :issue:`40468`.) Move the indent space setting from the Font tab to
|
||
the new Windows tab. (Contributed by Mark Roseman and Terry Jan Reedy in
|
||
:issue:`33962`.)
|
||
|
||
The changes above were backported to a 3.9 maintenance release.
|
||
|
||
Add a Shell sidebar. Move the primary prompt ('>>>') to the sidebar.
|
||
Add secondary prompts ('...') to the sidebar. Left click and optional
|
||
drag selects one or more lines of text, as with the editor
|
||
line number sidebar. Right click after selecting text lines displays
|
||
a context menu with 'copy with prompts'. This zips together prompts
|
||
from the sidebar with lines from the selected text. This option also
|
||
appears on the context menu for the text. (Contributed by Tal Einat
|
||
in :issue:`37903`.)
|
||
|
||
Use spaces instead of tabs to indent interactive code. This makes
|
||
interactive code entries 'look right'. Making this feasible was a
|
||
major motivation for adding the shell sidebar. (Contributed by
|
||
Terry Jan Reedy in :issue:`37892`.)
|
||
|
||
Highlight the new :ref:`soft keywords <soft-keywords>` :keyword:`match`,
|
||
:keyword:`case <match>`, and :keyword:`_ <wildcard-patterns>` in
|
||
pattern-matching statements. However, this highlighting is not perfect
|
||
and will be incorrect in some rare cases, including some ``_``-s in
|
||
``case`` patterns. (Contributed by Tal Einat in :issue:`44010`.)
|
||
|
||
New in 3.10 maintenance releases.
|
||
|
||
Apply syntax highlighting to ``.pyi`` files. (Contributed by Alex
|
||
Waygood and Terry Jan Reedy in :issue:`45447`.)
|
||
|
||
Include prompts when saving Shell with inputs and outputs.
|
||
(Contributed by Terry Jan Reedy in :gh:`95191`.)
|
||
|
||
importlib.metadata
|
||
------------------
|
||
|
||
Feature parity with ``importlib_metadata`` 4.6
|
||
(`history <https://importlib-metadata.readthedocs.io/en/latest/history.html>`_).
|
||
|
||
:ref:`importlib.metadata entry points <entry-points>`
|
||
now provide a nicer experience
|
||
for selecting entry points by group and name through a new
|
||
:ref:`importlib.metadata.EntryPoints <entry-points>` class. See the Compatibility
|
||
Note in the docs for more info on the deprecation and usage.
|
||
|
||
Added :ref:`importlib.metadata.packages_distributions() <package-distributions>`
|
||
for resolving top-level Python modules and packages to their
|
||
:ref:`importlib.metadata.Distribution <distributions>`.
|
||
|
||
inspect
|
||
-------
|
||
|
||
When a module does not define ``__loader__``, fall back to ``__spec__.loader``.
|
||
(Contributed by Brett Cannon in :issue:`42133`.)
|
||
|
||
Add :func:`inspect.get_annotations`, which safely computes the annotations
|
||
defined on an object. It works around the quirks of accessing the annotations
|
||
on various types of objects, and makes very few assumptions about the object
|
||
it examines. :func:`inspect.get_annotations` can also correctly un-stringize
|
||
stringized annotations. :func:`inspect.get_annotations` is now considered
|
||
best practice for accessing the annotations dict defined on any Python object;
|
||
for more information on best practices for working with annotations, please see
|
||
:ref:`annotations-howto`.
|
||
Relatedly, :func:`inspect.signature`,
|
||
:func:`inspect.Signature.from_callable`, and :func:`!inspect.Signature.from_function`
|
||
now call :func:`inspect.get_annotations` to retrieve annotations. This means
|
||
:func:`inspect.signature` and :func:`inspect.Signature.from_callable` can
|
||
also now un-stringize stringized annotations.
|
||
(Contributed by Larry Hastings in :issue:`43817`.)
|
||
|
||
itertools
|
||
---------
|
||
|
||
Add :func:`itertools.pairwise`.
|
||
(Contributed by Raymond Hettinger in :issue:`38200`.)
|
||
|
||
linecache
|
||
---------
|
||
|
||
When a module does not define ``__loader__``, fall back to ``__spec__.loader``.
|
||
(Contributed by Brett Cannon in :issue:`42133`.)
|
||
|
||
os
|
||
--
|
||
|
||
Add :func:`os.cpu_count` support for VxWorks RTOS.
|
||
(Contributed by Peixing Xin in :issue:`41440`.)
|
||
|
||
Add a new function :func:`os.eventfd` and related helpers to wrap the
|
||
``eventfd2`` syscall on Linux.
|
||
(Contributed by Christian Heimes in :issue:`41001`.)
|
||
|
||
Add :func:`os.splice` that allows to move data between two file
|
||
descriptors without copying between kernel address space and user
|
||
address space, where one of the file descriptors must refer to a
|
||
pipe. (Contributed by Pablo Galindo in :issue:`41625`.)
|
||
|
||
Add :const:`~os.O_EVTONLY`, :const:`~os.O_FSYNC`, :const:`~os.O_SYMLINK`
|
||
and :const:`~os.O_NOFOLLOW_ANY` for macOS.
|
||
(Contributed by Donghee Na in :issue:`43106`.)
|
||
|
||
os.path
|
||
-------
|
||
|
||
:func:`os.path.realpath` now accepts a *strict* keyword-only argument. When set
|
||
to ``True``, :exc:`OSError` is raised if a path doesn't exist or a symlink loop
|
||
is encountered.
|
||
(Contributed by Barney Gale in :issue:`43757`.)
|
||
|
||
pathlib
|
||
-------
|
||
|
||
Add slice support to :attr:`PurePath.parents <pathlib.PurePath.parents>`.
|
||
(Contributed by Joshua Cannon in :issue:`35498`.)
|
||
|
||
Add negative indexing support to :attr:`PurePath.parents
|
||
<pathlib.PurePath.parents>`.
|
||
(Contributed by Yaroslav Pankovych in :issue:`21041`.)
|
||
|
||
Add :meth:`Path.hardlink_to <pathlib.Path.hardlink_to>` method that
|
||
supersedes :meth:`!link_to`. The new method has the same argument
|
||
order as :meth:`~pathlib.Path.symlink_to`.
|
||
(Contributed by Barney Gale in :issue:`39950`.)
|
||
|
||
:meth:`pathlib.Path.stat` and :meth:`~pathlib.Path.chmod` now accept a
|
||
*follow_symlinks* keyword-only argument for consistency with corresponding
|
||
functions in the :mod:`os` module.
|
||
(Contributed by Barney Gale in :issue:`39906`.)
|
||
|
||
platform
|
||
--------
|
||
|
||
Add :func:`platform.freedesktop_os_release` to retrieve operation system
|
||
identification from `freedesktop.org os-release
|
||
<https://www.freedesktop.org/software/systemd/man/os-release.html>`_ standard file.
|
||
(Contributed by Christian Heimes in :issue:`28468`.)
|
||
|
||
pprint
|
||
------
|
||
|
||
:func:`pprint.pprint` now accepts a new ``underscore_numbers`` keyword argument.
|
||
(Contributed by sblondon in :issue:`42914`.)
|
||
|
||
:mod:`pprint` can now pretty-print :class:`dataclasses.dataclass` instances.
|
||
(Contributed by Lewis Gaul in :issue:`43080`.)
|
||
|
||
py_compile
|
||
----------
|
||
|
||
Add ``--quiet`` option to command-line interface of :mod:`py_compile`.
|
||
(Contributed by Gregory Schevchenko in :issue:`38731`.)
|
||
|
||
pyclbr
|
||
------
|
||
|
||
Add an ``end_lineno`` attribute to the ``Function`` and ``Class``
|
||
objects in the tree returned by :func:`pyclbr.readmodule` and
|
||
:func:`pyclbr.readmodule_ex`. It matches the existing (start) ``lineno``.
|
||
(Contributed by Aviral Srivastava in :issue:`38307`.)
|
||
|
||
shelve
|
||
------
|
||
|
||
The :mod:`shelve` module now uses :const:`pickle.DEFAULT_PROTOCOL` by default
|
||
instead of :mod:`pickle` protocol ``3`` when creating shelves.
|
||
(Contributed by Zackery Spytz in :issue:`34204`.)
|
||
|
||
statistics
|
||
----------
|
||
|
||
Add :func:`~statistics.covariance`, Pearson's
|
||
:func:`~statistics.correlation`, and simple
|
||
:func:`~statistics.linear_regression` functions.
|
||
(Contributed by Tymoteusz Wołodźko in :issue:`38490`.)
|
||
|
||
site
|
||
----
|
||
|
||
When a module does not define ``__loader__``, fall back to ``__spec__.loader``.
|
||
(Contributed by Brett Cannon in :issue:`42133`.)
|
||
|
||
socket
|
||
------
|
||
|
||
The exception :exc:`socket.timeout` is now an alias of :exc:`TimeoutError`.
|
||
(Contributed by Christian Heimes in :issue:`42413`.)
|
||
|
||
Add option to create MPTCP sockets with ``IPPROTO_MPTCP``
|
||
(Contributed by Rui Cunha in :issue:`43571`.)
|
||
|
||
Add ``IP_RECVTOS`` option to receive the type of service (ToS) or DSCP/ECN fields
|
||
(Contributed by Georg Sauthoff in :issue:`44077`.)
|
||
|
||
ssl
|
||
---
|
||
|
||
The ssl module requires OpenSSL 1.1.1 or newer.
|
||
(Contributed by Christian Heimes in :pep:`644` and :issue:`43669`.)
|
||
|
||
The ssl module has preliminary support for OpenSSL 3.0.0 and new option
|
||
:const:`~ssl.OP_IGNORE_UNEXPECTED_EOF`.
|
||
(Contributed by Christian Heimes in :issue:`38820`, :issue:`43794`,
|
||
:issue:`43788`, :issue:`43791`, :issue:`43799`, :issue:`43920`,
|
||
:issue:`43789`, and :issue:`43811`.)
|
||
|
||
Deprecated function and use of deprecated constants now result in
|
||
a :exc:`DeprecationWarning`. :attr:`ssl.SSLContext.options` has
|
||
:data:`~ssl.OP_NO_SSLv2` and :data:`~ssl.OP_NO_SSLv3` set by default and
|
||
therefore cannot warn about setting the flag again. The
|
||
:ref:`deprecation section <whatsnew310-deprecated>` has a list of deprecated
|
||
features.
|
||
(Contributed by Christian Heimes in :issue:`43880`.)
|
||
|
||
The ssl module now has more secure default settings. Ciphers without forward
|
||
secrecy or SHA-1 MAC are disabled by default. Security level 2 prohibits
|
||
weak RSA, DH, and ECC keys with less than 112 bits of security.
|
||
:class:`~ssl.SSLContext` defaults to minimum protocol version TLS 1.2.
|
||
Settings are based on Hynek Schlawack's research.
|
||
(Contributed by Christian Heimes in :issue:`43998`.)
|
||
|
||
The deprecated protocols SSL 3.0, TLS 1.0, and TLS 1.1 are no longer
|
||
officially supported. Python does not block them actively. However
|
||
OpenSSL build options, distro configurations, vendor patches, and cipher
|
||
suites may prevent a successful handshake.
|
||
|
||
Add a *timeout* parameter to the :func:`ssl.get_server_certificate` function.
|
||
(Contributed by Zackery Spytz in :issue:`31870`.)
|
||
|
||
The ssl module uses heap-types and multi-phase initialization.
|
||
(Contributed by Christian Heimes in :issue:`42333`.)
|
||
|
||
A new verify flag :const:`~ssl.VERIFY_X509_PARTIAL_CHAIN` has been added.
|
||
(Contributed by l0x in :issue:`40849`.)
|
||
|
||
sqlite3
|
||
-------
|
||
|
||
Add audit events for :func:`~sqlite3.connect/handle`,
|
||
:meth:`~sqlite3.Connection.enable_load_extension`, and
|
||
:meth:`~sqlite3.Connection.load_extension`.
|
||
(Contributed by Erlend E. Aasland in :issue:`43762`.)
|
||
|
||
sys
|
||
---
|
||
|
||
Add :data:`sys.orig_argv` attribute: the list of the original command line
|
||
arguments passed to the Python executable.
|
||
(Contributed by Victor Stinner in :issue:`23427`.)
|
||
|
||
Add :data:`sys.stdlib_module_names`, containing the list of the standard library
|
||
module names.
|
||
(Contributed by Victor Stinner in :issue:`42955`.)
|
||
|
||
_thread
|
||
-------
|
||
|
||
:func:`_thread.interrupt_main` now takes an optional signal number to
|
||
simulate (the default is still :const:`signal.SIGINT`).
|
||
(Contributed by Antoine Pitrou in :issue:`43356`.)
|
||
|
||
threading
|
||
---------
|
||
|
||
Add :func:`threading.gettrace` and :func:`threading.getprofile` to
|
||
retrieve the functions set by :func:`threading.settrace` and
|
||
:func:`threading.setprofile` respectively.
|
||
(Contributed by Mario Corchero in :issue:`42251`.)
|
||
|
||
Add :data:`threading.__excepthook__` to allow retrieving the original value
|
||
of :func:`threading.excepthook` in case it is set to a broken or a different
|
||
value.
|
||
(Contributed by Mario Corchero in :issue:`42308`.)
|
||
|
||
traceback
|
||
---------
|
||
|
||
The :func:`~traceback.format_exception`,
|
||
:func:`~traceback.format_exception_only`, and
|
||
:func:`~traceback.print_exception` functions can now take an exception object
|
||
as a positional-only argument.
|
||
(Contributed by Zackery Spytz and Matthias Bussonnier in :issue:`26389`.)
|
||
|
||
types
|
||
-----
|
||
|
||
Reintroduce the :data:`types.EllipsisType`, :data:`types.NoneType`
|
||
and :data:`types.NotImplementedType` classes, providing a new set
|
||
of types readily interpretable by type checkers.
|
||
(Contributed by Bas van Beek in :issue:`41810`.)
|
||
|
||
typing
|
||
------
|
||
|
||
For major changes, see :ref:`new-feat-related-type-hints`.
|
||
|
||
The behavior of :class:`typing.Literal` was changed to conform with :pep:`586`
|
||
and to match the behavior of static type checkers specified in the PEP.
|
||
|
||
1. ``Literal`` now de-duplicates parameters.
|
||
2. Equality comparisons between ``Literal`` objects are now order independent.
|
||
3. ``Literal`` comparisons now respect types. For example,
|
||
``Literal[0] == Literal[False]`` previously evaluated to ``True``. It is
|
||
now ``False``. To support this change, the internally used type cache now
|
||
supports differentiating types.
|
||
4. ``Literal`` objects will now raise a :exc:`TypeError` exception during
|
||
equality comparisons if any of their parameters are not :term:`hashable`.
|
||
Note that declaring ``Literal`` with unhashable parameters will not throw
|
||
an error::
|
||
|
||
>>> from typing import Literal
|
||
>>> Literal[{0}]
|
||
>>> Literal[{0}] == Literal[{False}]
|
||
Traceback (most recent call last):
|
||
File "<stdin>", line 1, in <module>
|
||
TypeError: unhashable type: 'set'
|
||
|
||
(Contributed by Yurii Karabas in :issue:`42345`.)
|
||
|
||
Add new function :func:`typing.is_typeddict` to introspect if an annotation
|
||
is a :class:`typing.TypedDict`.
|
||
(Contributed by Patrick Reader in :issue:`41792`.)
|
||
|
||
Subclasses of ``typing.Protocol`` which only have data variables declared
|
||
will now raise a ``TypeError`` when checked with ``isinstance`` unless they
|
||
are decorated with :func:`~typing.runtime_checkable`. Previously, these checks
|
||
passed silently. Users should decorate their
|
||
subclasses with the :func:`!runtime_checkable` decorator
|
||
if they want runtime protocols.
|
||
(Contributed by Yurii Karabas in :issue:`38908`.)
|
||
|
||
Importing from the ``typing.io`` and ``typing.re`` submodules will now emit
|
||
:exc:`DeprecationWarning`. These submodules have been deprecated since
|
||
Python 3.8 and will be removed in a future version of Python. Anything
|
||
belonging to those submodules should be imported directly from
|
||
:mod:`typing` instead.
|
||
(Contributed by Sebastian Rittau in :issue:`38291`.)
|
||
|
||
unittest
|
||
--------
|
||
|
||
Add new method :meth:`~unittest.TestCase.assertNoLogs` to complement the
|
||
existing :meth:`~unittest.TestCase.assertLogs`. (Contributed by Kit Yan Choi
|
||
in :issue:`39385`.)
|
||
|
||
urllib.parse
|
||
------------
|
||
|
||
Python versions earlier than Python 3.10 allowed using both ``;`` and ``&`` as
|
||
query parameter separators in :func:`urllib.parse.parse_qs` and
|
||
:func:`urllib.parse.parse_qsl`. Due to security concerns, and to conform with
|
||
newer W3C recommendations, this has been changed to allow only a single
|
||
separator key, with ``&`` as the default. This change also affects
|
||
:func:`!cgi.parse` and :func:`!cgi.parse_multipart` as they use the affected
|
||
functions internally. For more details, please see their respective
|
||
documentation.
|
||
(Contributed by Adam Goldschmidt, Senthil Kumaran and Ken Jin in :issue:`42967`.)
|
||
|
||
The presence of newline or tab characters in parts of a URL allows for some
|
||
forms of attacks. Following the WHATWG specification that updates :rfc:`3986`,
|
||
ASCII newline ``\n``, ``\r`` and tab ``\t`` characters are stripped from the
|
||
URL by the parser in :mod:`urllib.parse` preventing such attacks. The removal
|
||
characters are controlled by a new module level variable
|
||
``urllib.parse._UNSAFE_URL_BYTES_TO_REMOVE``. (See :gh:`88048`)
|
||
|
||
xml
|
||
---
|
||
|
||
Add a :class:`~xml.sax.handler.LexicalHandler` class to the
|
||
:mod:`xml.sax.handler` module.
|
||
(Contributed by Jonathan Gossage and Zackery Spytz in :issue:`35018`.)
|
||
|
||
zipimport
|
||
---------
|
||
Add methods related to :pep:`451`: :meth:`~zipimport.zipimporter.find_spec`,
|
||
:meth:`zipimport.zipimporter.create_module`, and
|
||
:meth:`zipimport.zipimporter.exec_module`.
|
||
(Contributed by Brett Cannon in :issue:`42131`.)
|
||
|
||
Add :meth:`~zipimport.zipimporter.invalidate_caches` method.
|
||
(Contributed by Desmond Cheong in :issue:`14678`.)
|
||
|
||
|
||
Optimizations
|
||
=============
|
||
|
||
* Constructors :func:`str`, :func:`bytes` and :func:`bytearray` are now faster
|
||
(around 30--40% for small objects).
|
||
(Contributed by Serhiy Storchaka in :issue:`41334`.)
|
||
|
||
* The :mod:`runpy` module now imports fewer modules.
|
||
The ``python3 -m module-name`` command startup time is 1.4x faster in
|
||
average. On Linux, ``python3 -I -m module-name`` imports 69 modules on Python
|
||
3.9, whereas it only imports 51 modules (-18) on Python 3.10.
|
||
(Contributed by Victor Stinner in :issue:`41006` and :issue:`41718`.)
|
||
|
||
* The ``LOAD_ATTR`` instruction now uses new "per opcode cache" mechanism. It
|
||
is about 36% faster now for regular attributes and 44% faster for slots.
|
||
(Contributed by Pablo Galindo and Yury Selivanov in :issue:`42093` and Guido
|
||
van Rossum in :issue:`42927`, based on ideas implemented originally in PyPy
|
||
and MicroPython.)
|
||
|
||
* When building Python with :option:`--enable-optimizations` now
|
||
``-fno-semantic-interposition`` is added to both the compile and link line.
|
||
This speeds builds of the Python interpreter created with :option:`--enable-shared`
|
||
with ``gcc`` by up to 30%. See `this article
|
||
<https://developers.redhat.com/blog/2020/06/25/red-hat-enterprise-linux-8-2-brings-faster-python-3-8-run-speeds/>`_
|
||
for more details. (Contributed by Victor Stinner and Pablo Galindo in
|
||
:issue:`38980`.)
|
||
|
||
* Use a new output buffer management code for :mod:`bz2` / :mod:`lzma` /
|
||
:mod:`zlib` modules, and add ``.readall()`` function to
|
||
``_compression.DecompressReader`` class. bz2 decompression is now 1.09x ~ 1.17x
|
||
faster, lzma decompression 1.20x ~ 1.32x faster, ``GzipFile.read(-1)`` 1.11x
|
||
~ 1.18x faster. (Contributed by Ma Lin, reviewed by Gregory P. Smith, in :issue:`41486`)
|
||
|
||
* When using stringized annotations, annotations dicts for functions are no longer
|
||
created when the function is created. Instead, they are stored as a tuple of
|
||
strings, and the function object lazily converts this into the annotations dict
|
||
on demand. This optimization cuts the CPU time needed to define an annotated
|
||
function by half.
|
||
(Contributed by Yurii Karabas and Inada Naoki in :issue:`42202`.)
|
||
|
||
* Substring search functions such as ``str1 in str2`` and ``str2.find(str1)``
|
||
now sometimes use Crochemore & Perrin's "Two-Way" string searching
|
||
algorithm to avoid quadratic behavior on long strings. (Contributed
|
||
by Dennis Sweeney in :issue:`41972`)
|
||
|
||
* Add micro-optimizations to ``_PyType_Lookup()`` to improve type attribute cache lookup
|
||
performance in the common case of cache hits. This makes the interpreter 1.04 times faster
|
||
on average. (Contributed by Dino Viehland in :issue:`43452`.)
|
||
|
||
* The following built-in functions now support the faster :pep:`590` vectorcall calling convention:
|
||
:func:`map`, :func:`filter`, :func:`reversed`, :func:`bool` and :func:`float`.
|
||
(Contributed by Donghee Na and Jeroen Demeyer in :issue:`43575`, :issue:`43287`, :issue:`41922`, :issue:`41873` and :issue:`41870`.)
|
||
|
||
* :class:`~bz2.BZ2File` performance is improved by removing internal ``RLock``.
|
||
This makes :class:`!BZ2File` thread unsafe in the face of multiple simultaneous
|
||
readers or writers, just like its equivalent classes in :mod:`gzip` and
|
||
:mod:`lzma` have always been. (Contributed by Inada Naoki in :issue:`43785`.)
|
||
|
||
.. _whatsnew310-deprecated:
|
||
|
||
Deprecated
|
||
==========
|
||
|
||
* Currently Python accepts numeric literals immediately followed by keywords,
|
||
for example ``0in x``, ``1or x``, ``0if 1else 2``. It allows confusing
|
||
and ambiguous expressions like ``[0x1for x in y]`` (which can be
|
||
interpreted as ``[0x1 for x in y]`` or ``[0x1f or x in y]``). Starting in
|
||
this release, a deprecation warning is raised if the numeric literal is
|
||
immediately followed by one of keywords :keyword:`and`, :keyword:`else`,
|
||
:keyword:`for`, :keyword:`if`, :keyword:`in`, :keyword:`is` and :keyword:`or`.
|
||
In future releases it will be changed to syntax warning, and finally to
|
||
syntax error.
|
||
(Contributed by Serhiy Storchaka in :issue:`43833`.)
|
||
|
||
* Starting in this release, there will be a concerted effort to begin
|
||
cleaning up old import semantics that were kept for Python 2.7
|
||
compatibility. Specifically,
|
||
:meth:`!find_loader`/:meth:`!find_module`
|
||
(superseded by :meth:`~importlib.abc.MetaPathFinder.find_spec`),
|
||
:meth:`~importlib.abc.Loader.load_module`
|
||
(superseded by :meth:`~importlib.abc.Loader.exec_module`),
|
||
:meth:`!module_repr` (which the import system
|
||
takes care of for you), the ``__package__`` attribute
|
||
(superseded by ``__spec__.parent``), the ``__loader__`` attribute
|
||
(superseded by ``__spec__.loader``), and the ``__cached__`` attribute
|
||
(superseded by ``__spec__.cached``) will slowly be removed (as well
|
||
as other classes and methods in :mod:`importlib`).
|
||
:exc:`ImportWarning` and/or :exc:`DeprecationWarning` will be raised
|
||
as appropriate to help identify code which needs updating during
|
||
this transition.
|
||
|
||
* The entire ``distutils`` namespace is deprecated, to be removed in
|
||
Python 3.12. Refer to the :ref:`module changes <distutils-deprecated>`
|
||
section for more information.
|
||
|
||
* Non-integer arguments to :func:`random.randrange` are deprecated.
|
||
The :exc:`ValueError` is deprecated in favor of a :exc:`TypeError`.
|
||
(Contributed by Serhiy Storchaka and Raymond Hettinger in :issue:`37319`.)
|
||
|
||
* The various ``load_module()`` methods of :mod:`importlib` have been
|
||
documented as deprecated since Python 3.6, but will now also trigger
|
||
a :exc:`DeprecationWarning`. Use
|
||
:meth:`~importlib.abc.Loader.exec_module` instead.
|
||
(Contributed by Brett Cannon in :issue:`26131`.)
|
||
|
||
* :meth:`!zimport.zipimporter.load_module` has been deprecated in
|
||
preference for :meth:`~zipimport.zipimporter.exec_module`.
|
||
(Contributed by Brett Cannon in :issue:`26131`.)
|
||
|
||
* The use of :meth:`~importlib.abc.Loader.load_module` by the import
|
||
system now triggers an :exc:`ImportWarning` as
|
||
:meth:`~importlib.abc.Loader.exec_module` is preferred.
|
||
(Contributed by Brett Cannon in :issue:`26131`.)
|
||
|
||
* The use of :meth:`!importlib.abc.MetaPathFinder.find_module` and
|
||
:meth:`!importlib.abc.PathEntryFinder.find_module` by the import system now
|
||
trigger an :exc:`ImportWarning` as
|
||
:meth:`importlib.abc.MetaPathFinder.find_spec` and
|
||
:meth:`importlib.abc.PathEntryFinder.find_spec`
|
||
are preferred, respectively. You can use
|
||
:func:`importlib.util.spec_from_loader` to help in porting.
|
||
(Contributed by Brett Cannon in :issue:`42134`.)
|
||
|
||
* The use of :meth:`!importlib.abc.PathEntryFinder.find_loader` by the import
|
||
system now triggers an :exc:`ImportWarning` as
|
||
:meth:`importlib.abc.PathEntryFinder.find_spec` is preferred. You can use
|
||
:func:`importlib.util.spec_from_loader` to help in porting.
|
||
(Contributed by Brett Cannon in :issue:`43672`.)
|
||
|
||
* The various implementations of
|
||
:meth:`!importlib.abc.MetaPathFinder.find_module` (
|
||
:meth:`!importlib.machinery.BuiltinImporter.find_module`,
|
||
:meth:`!importlib.machinery.FrozenImporter.find_module`,
|
||
:meth:`!importlib.machinery.WindowsRegistryFinder.find_module`,
|
||
:meth:`!importlib.machinery.PathFinder.find_module`,
|
||
:meth:`!importlib.abc.MetaPathFinder.find_module` ),
|
||
:meth:`!importlib.abc.PathEntryFinder.find_module` (
|
||
:meth:`!importlib.machinery.FileFinder.find_module` ), and
|
||
:meth:`!importlib.abc.PathEntryFinder.find_loader` (
|
||
:meth:`!importlib.machinery.FileFinder.find_loader` )
|
||
now raise :exc:`DeprecationWarning` and are slated for removal in
|
||
Python 3.12 (previously they were documented as deprecated in Python 3.4).
|
||
(Contributed by Brett Cannon in :issue:`42135`.)
|
||
|
||
* :class:`!importlib.abc.Finder` is deprecated (including its sole method,
|
||
:meth:`!find_module`). Both
|
||
:class:`importlib.abc.MetaPathFinder` and :class:`importlib.abc.PathEntryFinder`
|
||
no longer inherit from the class. Users should inherit from one of these two
|
||
classes as appropriate instead.
|
||
(Contributed by Brett Cannon in :issue:`42135`.)
|
||
|
||
* The deprecations of :mod:`!imp`, :func:`!importlib.find_loader`,
|
||
:func:`!importlib.util.set_package_wrapper`,
|
||
:func:`!importlib.util.set_loader_wrapper`,
|
||
:func:`!importlib.util.module_for_loader`,
|
||
:class:`!pkgutil.ImpImporter`, and
|
||
:class:`!pkgutil.ImpLoader` have all been updated to list Python 3.12 as the
|
||
slated version of removal (they began raising :exc:`DeprecationWarning` in
|
||
previous versions of Python).
|
||
(Contributed by Brett Cannon in :issue:`43720`.)
|
||
|
||
* The import system now uses the ``__spec__`` attribute on modules before
|
||
falling back on :meth:`!module_repr` for a module's
|
||
``__repr__()`` method. Removal of the use of ``module_repr()`` is scheduled
|
||
for Python 3.12.
|
||
(Contributed by Brett Cannon in :issue:`42137`.)
|
||
|
||
* :meth:`!importlib.abc.Loader.module_repr`,
|
||
:meth:`!importlib.machinery.FrozenLoader.module_repr`, and
|
||
:meth:`!importlib.machinery.BuiltinLoader.module_repr` are deprecated and
|
||
slated for removal in Python 3.12.
|
||
(Contributed by Brett Cannon in :issue:`42136`.)
|
||
|
||
* ``sqlite3.OptimizedUnicode`` has been undocumented and obsolete since Python
|
||
3.3, when it was made an alias to :class:`str`. It is now deprecated,
|
||
scheduled for removal in Python 3.12.
|
||
(Contributed by Erlend E. Aasland in :issue:`42264`.)
|
||
|
||
* The undocumented built-in function ``sqlite3.enable_shared_cache`` is now
|
||
deprecated, scheduled for removal in Python 3.12. Its use is strongly
|
||
discouraged by the SQLite3 documentation. See `the SQLite3 docs
|
||
<https://sqlite.org/c3ref/enable_shared_cache.html>`_ for more details.
|
||
If a shared cache must be used, open the database in URI mode using the
|
||
``cache=shared`` query parameter.
|
||
(Contributed by Erlend E. Aasland in :issue:`24464`.)
|
||
|
||
* The following ``threading`` methods are now deprecated:
|
||
|
||
* ``threading.currentThread`` => :func:`threading.current_thread`
|
||
|
||
* ``threading.activeCount`` => :func:`threading.active_count`
|
||
|
||
* ``threading.Condition.notifyAll`` =>
|
||
:meth:`threading.Condition.notify_all`
|
||
|
||
* ``threading.Event.isSet`` => :meth:`threading.Event.is_set`
|
||
|
||
* ``threading.Thread.setName`` => :attr:`threading.Thread.name`
|
||
|
||
* ``threading.thread.getName`` => :attr:`threading.Thread.name`
|
||
|
||
* ``threading.Thread.isDaemon`` => :attr:`threading.Thread.daemon`
|
||
|
||
* ``threading.Thread.setDaemon`` => :attr:`threading.Thread.daemon`
|
||
|
||
(Contributed by Jelle Zijlstra in :gh:`87889`.)
|
||
|
||
* :meth:`!pathlib.Path.link_to` is deprecated and slated for removal in
|
||
Python 3.12. Use :meth:`pathlib.Path.hardlink_to` instead.
|
||
(Contributed by Barney Gale in :issue:`39950`.)
|
||
|
||
* ``cgi.log()`` is deprecated and slated for removal in Python 3.12.
|
||
(Contributed by Inada Naoki in :issue:`41139`.)
|
||
|
||
* The following :mod:`ssl` features have been deprecated since Python 3.6,
|
||
Python 3.7, or OpenSSL 1.1.0 and will be removed in 3.11:
|
||
|
||
* :data:`!OP_NO_SSLv2`, :data:`!OP_NO_SSLv3`, :data:`!OP_NO_TLSv1`,
|
||
:data:`!OP_NO_TLSv1_1`, :data:`!OP_NO_TLSv1_2`, and
|
||
:data:`!OP_NO_TLSv1_3` are replaced by
|
||
:attr:`~ssl.SSLContext.minimum_version` and
|
||
:attr:`~ssl.SSLContext.maximum_version`.
|
||
|
||
* :data:`!PROTOCOL_SSLv2`, :data:`!PROTOCOL_SSLv3`,
|
||
:data:`!PROTOCOL_SSLv23`, :data:`!PROTOCOL_TLSv1`,
|
||
:data:`!PROTOCOL_TLSv1_1`, :data:`!PROTOCOL_TLSv1_2`, and
|
||
:const:`!PROTOCOL_TLS` are deprecated in favor of
|
||
:const:`~ssl.PROTOCOL_TLS_CLIENT` and :const:`~ssl.PROTOCOL_TLS_SERVER`
|
||
|
||
* :func:`!wrap_socket` is replaced by :meth:`ssl.SSLContext.wrap_socket`
|
||
|
||
* :func:`!match_hostname`
|
||
|
||
* :func:`!RAND_pseudo_bytes`, :func:`!RAND_egd`
|
||
|
||
* NPN features like :meth:`ssl.SSLSocket.selected_npn_protocol` and
|
||
:meth:`ssl.SSLContext.set_npn_protocols` are replaced by ALPN.
|
||
|
||
* The threading debug (:envvar:`!PYTHONTHREADDEBUG` environment variable) is
|
||
deprecated in Python 3.10 and will be removed in Python 3.12. This feature
|
||
requires a :ref:`debug build of Python <debug-build>`.
|
||
(Contributed by Victor Stinner in :issue:`44584`.)
|
||
|
||
* Importing from the ``typing.io`` and ``typing.re`` submodules will now emit
|
||
:exc:`DeprecationWarning`. These submodules will be removed in a future version
|
||
of Python. Anything belonging to these submodules should be imported directly
|
||
from :mod:`typing` instead.
|
||
(Contributed by Sebastian Rittau in :issue:`38291`.)
|
||
|
||
.. _whatsnew310-removed:
|
||
|
||
Removed
|
||
=======
|
||
|
||
* Removed special methods ``__int__``, ``__float__``, ``__floordiv__``,
|
||
``__mod__``, ``__divmod__``, ``__rfloordiv__``, ``__rmod__`` and
|
||
``__rdivmod__`` of the :class:`complex` class. They always raised
|
||
a :exc:`TypeError`.
|
||
(Contributed by Serhiy Storchaka in :issue:`41974`.)
|
||
|
||
* The ``ParserBase.error()`` method from the private and undocumented ``_markupbase``
|
||
module has been removed. :class:`html.parser.HTMLParser` is the only subclass of
|
||
``ParserBase`` and its ``error()`` implementation was already removed in
|
||
Python 3.5.
|
||
(Contributed by Berker Peksag in :issue:`31844`.)
|
||
|
||
* Removed the ``unicodedata.ucnhash_CAPI`` attribute which was an internal
|
||
PyCapsule object. The related private ``_PyUnicode_Name_CAPI`` structure was
|
||
moved to the internal C API.
|
||
(Contributed by Victor Stinner in :issue:`42157`.)
|
||
|
||
* Removed the ``parser`` module, which was deprecated in 3.9 due to the
|
||
switch to the new PEG parser, as well as all the C source and header files
|
||
that were only being used by the old parser, including ``node.h``, ``parser.h``,
|
||
``graminit.h`` and ``grammar.h``.
|
||
|
||
* Removed the Public C API functions ``PyParser_SimpleParseStringFlags``,
|
||
``PyParser_SimpleParseStringFlagsFilename``,
|
||
``PyParser_SimpleParseFileFlags`` and ``PyNode_Compile``
|
||
that were deprecated in 3.9 due to the switch to the new PEG parser.
|
||
|
||
* Removed the ``formatter`` module, which was deprecated in Python 3.4.
|
||
It is somewhat obsolete, little used, and not tested. It was originally
|
||
scheduled to be removed in Python 3.6, but such removals were delayed until
|
||
after Python 2.7 EOL. Existing users should copy whatever classes they use
|
||
into their code.
|
||
(Contributed by Donghee Na and Terry J. Reedy in :issue:`42299`.)
|
||
|
||
* Removed the :c:func:`!PyModule_GetWarningsModule` function that was useless
|
||
now due to the :mod:`!_warnings` module was converted to a builtin module in 2.6.
|
||
(Contributed by Hai Shi in :issue:`42599`.)
|
||
|
||
* Remove deprecated aliases to :ref:`collections-abstract-base-classes` from
|
||
the :mod:`collections` module.
|
||
(Contributed by Victor Stinner in :issue:`37324`.)
|
||
|
||
* The ``loop`` parameter has been removed from most of :mod:`asyncio`\ 's
|
||
:doc:`high-level API <../library/asyncio-api-index>` following deprecation
|
||
in Python 3.8. The motivation behind this change is multifold:
|
||
|
||
1. This simplifies the high-level API.
|
||
2. The functions in the high-level API have been implicitly getting the
|
||
current thread's running event loop since Python 3.7. There isn't a need to
|
||
pass the event loop to the API in most normal use cases.
|
||
3. Event loop passing is error-prone especially when dealing with loops
|
||
running in different threads.
|
||
|
||
Note that the low-level API will still accept ``loop``.
|
||
See :ref:`changes-python-api` for examples of how to replace existing code.
|
||
|
||
(Contributed by Yurii Karabas, Andrew Svetlov, Yury Selivanov and Kyle Stanley
|
||
in :issue:`42392`.)
|
||
|
||
|
||
Porting to Python 3.10
|
||
======================
|
||
|
||
This section lists previously described changes and other bugfixes
|
||
that may require changes to your code.
|
||
|
||
|
||
Changes in the Python syntax
|
||
----------------------------
|
||
|
||
* Deprecation warning is now emitted when compiling previously valid syntax
|
||
if the numeric literal is immediately followed by a keyword (like in ``0in x``).
|
||
In future releases it will be changed to syntax warning, and finally to a
|
||
syntax error. To get rid of the warning and make the code compatible with
|
||
future releases just add a space between the numeric literal and the
|
||
following keyword.
|
||
(Contributed by Serhiy Storchaka in :issue:`43833`.)
|
||
|
||
.. _changes-python-api:
|
||
|
||
Changes in the Python API
|
||
-------------------------
|
||
|
||
* The *etype* parameters of the :func:`~traceback.format_exception`,
|
||
:func:`~traceback.format_exception_only`, and
|
||
:func:`~traceback.print_exception` functions in the :mod:`traceback` module
|
||
have been renamed to *exc*.
|
||
(Contributed by Zackery Spytz and Matthias Bussonnier in :issue:`26389`.)
|
||
|
||
* :mod:`atexit`: At Python exit, if a callback registered with
|
||
:func:`atexit.register` fails, its exception is now logged. Previously, only
|
||
some exceptions were logged, and the last exception was always silently
|
||
ignored.
|
||
(Contributed by Victor Stinner in :issue:`42639`.)
|
||
|
||
* :class:`collections.abc.Callable` generic now flattens type parameters, similar
|
||
to what :data:`typing.Callable` currently does. This means that
|
||
``collections.abc.Callable[[int, str], str]`` will have ``__args__`` of
|
||
``(int, str, str)``; previously this was ``([int, str], str)``. Code which
|
||
accesses the arguments via :func:`typing.get_args` or ``__args__`` need to account
|
||
for this change. Furthermore, :exc:`TypeError` may be raised for invalid forms
|
||
of parameterizing :class:`collections.abc.Callable` which may have passed
|
||
silently in Python 3.9.
|
||
(Contributed by Ken Jin in :issue:`42195`.)
|
||
|
||
* :meth:`socket.htons` and :meth:`socket.ntohs` now raise :exc:`OverflowError`
|
||
instead of :exc:`DeprecationWarning` if the given parameter will not fit in
|
||
a 16-bit unsigned integer.
|
||
(Contributed by Erlend E. Aasland in :issue:`42393`.)
|
||
|
||
* The ``loop`` parameter has been removed from most of :mod:`asyncio`\ 's
|
||
:doc:`high-level API <../library/asyncio-api-index>` following deprecation
|
||
in Python 3.8.
|
||
|
||
A coroutine that currently looks like this::
|
||
|
||
async def foo(loop):
|
||
await asyncio.sleep(1, loop=loop)
|
||
|
||
Should be replaced with this::
|
||
|
||
async def foo():
|
||
await asyncio.sleep(1)
|
||
|
||
If ``foo()`` was specifically designed *not* to run in the current thread's
|
||
running event loop (e.g. running in another thread's event loop), consider
|
||
using :func:`asyncio.run_coroutine_threadsafe` instead.
|
||
|
||
(Contributed by Yurii Karabas, Andrew Svetlov, Yury Selivanov and Kyle Stanley
|
||
in :issue:`42392`.)
|
||
|
||
* The :data:`types.FunctionType` constructor now inherits the current builtins
|
||
if the *globals* dictionary has no ``"__builtins__"`` key, rather than using
|
||
``{"None": None}`` as builtins: same behavior as :func:`eval` and
|
||
:func:`exec` functions. Defining a function with ``def function(...): ...``
|
||
in Python is not affected, globals cannot be overridden with this syntax: it
|
||
also inherits the current builtins.
|
||
(Contributed by Victor Stinner in :issue:`42990`.)
|
||
|
||
Changes in the C API
|
||
--------------------
|
||
|
||
* The C API functions ``PyParser_SimpleParseStringFlags``,
|
||
``PyParser_SimpleParseStringFlagsFilename``,
|
||
``PyParser_SimpleParseFileFlags``, ``PyNode_Compile`` and the type
|
||
used by these functions, ``struct _node``, were removed due to the switch
|
||
to the new PEG parser.
|
||
|
||
Source should be now be compiled directly to a code object using, for
|
||
example, :c:func:`Py_CompileString`. The resulting code object can then be
|
||
evaluated using, for example, :c:func:`PyEval_EvalCode`.
|
||
|
||
Specifically:
|
||
|
||
* A call to ``PyParser_SimpleParseStringFlags`` followed by
|
||
``PyNode_Compile`` can be replaced by calling :c:func:`Py_CompileString`.
|
||
|
||
* There is no direct replacement for ``PyParser_SimpleParseFileFlags``.
|
||
To compile code from a ``FILE *`` argument, you will need to read
|
||
the file in C and pass the resulting buffer to :c:func:`Py_CompileString`.
|
||
|
||
* To compile a file given a ``char *`` filename, explicitly open the file, read
|
||
it and compile the result. One way to do this is using the :py:mod:`io`
|
||
module with :c:func:`PyImport_ImportModule`, :c:func:`PyObject_CallMethod`,
|
||
:c:func:`PyBytes_AsString` and :c:func:`Py_CompileString`,
|
||
as sketched below. (Declarations and error handling are omitted.) ::
|
||
|
||
io_module = Import_ImportModule("io");
|
||
fileobject = PyObject_CallMethod(io_module, "open", "ss", filename, "rb");
|
||
source_bytes_object = PyObject_CallMethod(fileobject, "read", "");
|
||
result = PyObject_CallMethod(fileobject, "close", "");
|
||
source_buf = PyBytes_AsString(source_bytes_object);
|
||
code = Py_CompileString(source_buf, filename, Py_file_input);
|
||
|
||
* For ``FrameObject`` objects, the :attr:`~frame.f_lasti` member now represents a wordcode
|
||
offset instead of a simple offset into the bytecode string. This means that this
|
||
number needs to be multiplied by 2 to be used with APIs that expect a byte offset
|
||
instead (like :c:func:`PyCode_Addr2Line` for example). Notice as well that the
|
||
:attr:`!f_lasti` member of ``FrameObject`` objects is not considered stable: please
|
||
use :c:func:`PyFrame_GetLineNumber` instead.
|
||
|
||
CPython bytecode changes
|
||
========================
|
||
|
||
* The ``MAKE_FUNCTION`` instruction now accepts either a dict or a tuple of
|
||
strings as the function's annotations.
|
||
(Contributed by Yurii Karabas and Inada Naoki in :issue:`42202`.)
|
||
|
||
Build Changes
|
||
=============
|
||
|
||
* :pep:`644`: Python now requires OpenSSL 1.1.1 or newer. OpenSSL 1.0.2 is no
|
||
longer supported.
|
||
(Contributed by Christian Heimes in :issue:`43669`.)
|
||
|
||
* The C99 functions :c:func:`snprintf` and :c:func:`vsnprintf` are now required
|
||
to build Python.
|
||
(Contributed by Victor Stinner in :issue:`36020`.)
|
||
|
||
* :mod:`sqlite3` requires SQLite 3.7.15 or higher. (Contributed by Sergey Fedoseev
|
||
and Erlend E. Aasland in :issue:`40744` and :issue:`40810`.)
|
||
|
||
* The :mod:`atexit` module must now always be built as a built-in module.
|
||
(Contributed by Victor Stinner in :issue:`42639`.)
|
||
|
||
* Add :option:`--disable-test-modules` option to the ``configure`` script:
|
||
don't build nor install test modules.
|
||
(Contributed by Xavier de Gaye, Thomas Petazzoni and Peixing Xin in :issue:`27640`.)
|
||
|
||
* Add :option:`--with-wheel-pkg-dir=PATH option <--with-wheel-pkg-dir>`
|
||
to the ``./configure`` script. If
|
||
specified, the :mod:`ensurepip` module looks for ``setuptools`` and ``pip``
|
||
wheel packages in this directory: if both are present, these wheel packages
|
||
are used instead of ensurepip bundled wheel packages.
|
||
|
||
Some Linux distribution packaging policies recommend against bundling
|
||
dependencies. For example, Fedora installs wheel packages in the
|
||
``/usr/share/python-wheels/`` directory and don't install the
|
||
``ensurepip._bundled`` package.
|
||
|
||
(Contributed by Victor Stinner in :issue:`42856`.)
|
||
|
||
* Add a new :option:`configure --without-static-libpython option
|
||
<--without-static-libpython>` to not build the ``libpythonMAJOR.MINOR.a``
|
||
static library and not install the ``python.o`` object file.
|
||
|
||
(Contributed by Victor Stinner in :issue:`43103`.)
|
||
|
||
* The ``configure`` script now uses the ``pkg-config`` utility, if available,
|
||
to detect the location of Tcl/Tk headers and libraries. As before, those
|
||
locations can be explicitly specified with the ``--with-tcltk-includes``
|
||
and ``--with-tcltk-libs`` configuration options.
|
||
(Contributed by Manolis Stamatogiannakis in :issue:`42603`.)
|
||
|
||
* Add :option:`--with-openssl-rpath` option to ``configure`` script. The option
|
||
simplifies building Python with a custom OpenSSL installation, e.g.
|
||
``./configure --with-openssl=/path/to/openssl --with-openssl-rpath=auto``.
|
||
(Contributed by Christian Heimes in :issue:`43466`.)
|
||
|
||
|
||
C API Changes
|
||
=============
|
||
|
||
PEP 652: Maintaining the Stable ABI
|
||
-----------------------------------
|
||
|
||
The Stable ABI (Application Binary Interface) for extension modules or
|
||
embedding Python is now explicitly defined.
|
||
:ref:`stable` describes C API and ABI stability guarantees along with best
|
||
practices for using the Stable ABI.
|
||
|
||
(Contributed by Petr Viktorin in :pep:`652` and :issue:`43795`.)
|
||
|
||
New Features
|
||
------------
|
||
|
||
* The result of :c:func:`PyNumber_Index` now always has exact type :class:`int`.
|
||
Previously, the result could have been an instance of a subclass of ``int``.
|
||
(Contributed by Serhiy Storchaka in :issue:`40792`.)
|
||
|
||
* Add a new :c:member:`~PyConfig.orig_argv` member to the :c:type:`PyConfig`
|
||
structure: the list of the original command line arguments passed to the
|
||
Python executable.
|
||
(Contributed by Victor Stinner in :issue:`23427`.)
|
||
|
||
* The :c:func:`PyDateTime_DATE_GET_TZINFO` and
|
||
:c:func:`PyDateTime_TIME_GET_TZINFO` macros have been added for accessing
|
||
the ``tzinfo`` attributes of :class:`datetime.datetime` and
|
||
:class:`datetime.time` objects.
|
||
(Contributed by Zackery Spytz in :issue:`30155`.)
|
||
|
||
* Add a :c:func:`PyCodec_Unregister` function to unregister a codec
|
||
search function.
|
||
(Contributed by Hai Shi in :issue:`41842`.)
|
||
|
||
* The :c:func:`PyIter_Send` function was added to allow
|
||
sending value into iterator without raising ``StopIteration`` exception.
|
||
(Contributed by Vladimir Matveev in :issue:`41756`.)
|
||
|
||
* Add :c:func:`PyUnicode_AsUTF8AndSize` to the limited C API.
|
||
(Contributed by Alex Gaynor in :issue:`41784`.)
|
||
|
||
* Add :c:func:`PyModule_AddObjectRef` function: similar to
|
||
:c:func:`PyModule_AddObject` but don't steal a reference to the value on
|
||
success.
|
||
(Contributed by Victor Stinner in :issue:`1635741`.)
|
||
|
||
* Add :c:func:`Py_NewRef` and :c:func:`Py_XNewRef` functions to increment the
|
||
reference count of an object and return the object.
|
||
(Contributed by Victor Stinner in :issue:`42262`.)
|
||
|
||
* The :c:func:`PyType_FromSpecWithBases` and :c:func:`PyType_FromModuleAndSpec`
|
||
functions now accept a single class as the *bases* argument.
|
||
(Contributed by Serhiy Storchaka in :issue:`42423`.)
|
||
|
||
* The :c:func:`PyType_FromModuleAndSpec` function now accepts NULL ``tp_doc``
|
||
slot.
|
||
(Contributed by Hai Shi in :issue:`41832`.)
|
||
|
||
* The :c:func:`PyType_GetSlot` function can accept
|
||
:ref:`static types <static-types>`.
|
||
(Contributed by Hai Shi and Petr Viktorin in :issue:`41073`.)
|
||
|
||
* Add a new :c:func:`PySet_CheckExact` function to the C-API to check if an
|
||
object is an instance of :class:`set` but not an instance of a subtype.
|
||
(Contributed by Pablo Galindo in :issue:`43277`.)
|
||
|
||
* Add :c:func:`PyErr_SetInterruptEx` which allows passing a signal number
|
||
to simulate.
|
||
(Contributed by Antoine Pitrou in :issue:`43356`.)
|
||
|
||
* The limited C API is now supported if :ref:`Python is built in debug mode
|
||
<debug-build>` (if the ``Py_DEBUG`` macro is defined). In the limited C API,
|
||
the :c:func:`Py_INCREF` and :c:func:`Py_DECREF` functions are now implemented
|
||
as opaque function
|
||
calls, rather than accessing directly the :c:member:`PyObject.ob_refcnt`
|
||
member, if Python is built in debug mode and the ``Py_LIMITED_API`` macro
|
||
targets Python 3.10 or newer. It became possible to support the limited C API
|
||
in debug mode because the :c:type:`PyObject` structure is the same in release
|
||
and debug mode since Python 3.8 (see :issue:`36465`).
|
||
|
||
The limited C API is still not supported in the :option:`--with-trace-refs`
|
||
special build (``Py_TRACE_REFS`` macro).
|
||
(Contributed by Victor Stinner in :issue:`43688`.)
|
||
|
||
* Add the :c:func:`Py_Is(x, y) <Py_Is>` function to test if the *x* object is
|
||
the *y* object, the same as ``x is y`` in Python. Add also the
|
||
:c:func:`Py_IsNone`, :c:func:`Py_IsTrue`, :c:func:`Py_IsFalse` functions to
|
||
test if an object is, respectively, the ``None`` singleton, the ``True``
|
||
singleton or the ``False`` singleton.
|
||
(Contributed by Victor Stinner in :issue:`43753`.)
|
||
|
||
* Add new functions to control the garbage collector from C code:
|
||
:c:func:`PyGC_Enable()`,
|
||
:c:func:`PyGC_Disable()`,
|
||
:c:func:`PyGC_IsEnabled()`.
|
||
These functions allow to activate, deactivate and query the state of the garbage collector from C code without
|
||
having to import the :mod:`gc` module.
|
||
|
||
* Add a new :c:macro:`Py_TPFLAGS_DISALLOW_INSTANTIATION` type flag to disallow
|
||
creating type instances.
|
||
(Contributed by Victor Stinner in :issue:`43916`.)
|
||
|
||
* Add a new :c:macro:`Py_TPFLAGS_IMMUTABLETYPE` type flag for creating immutable
|
||
type objects: type attributes cannot be set nor deleted.
|
||
(Contributed by Victor Stinner and Erlend E. Aasland in :issue:`43908`.)
|
||
|
||
Porting to Python 3.10
|
||
----------------------
|
||
|
||
* The ``PY_SSIZE_T_CLEAN`` macro must now be defined to use
|
||
:c:func:`PyArg_ParseTuple` and :c:func:`Py_BuildValue` formats which use
|
||
``#``: ``es#``, ``et#``, ``s#``, ``u#``, ``y#``, ``z#``, ``U#`` and ``Z#``.
|
||
See :ref:`arg-parsing` and :pep:`353`.
|
||
(Contributed by Victor Stinner in :issue:`40943`.)
|
||
|
||
* Since :c:func:`Py_REFCNT()` is changed to the inline static function,
|
||
``Py_REFCNT(obj) = new_refcnt`` must be replaced with ``Py_SET_REFCNT(obj, new_refcnt)``:
|
||
see :c:func:`Py_SET_REFCNT()` (available since Python 3.9). For backward
|
||
compatibility, this macro can be used::
|
||
|
||
#if PY_VERSION_HEX < 0x030900A4
|
||
# define Py_SET_REFCNT(obj, refcnt) ((Py_REFCNT(obj) = (refcnt)), (void)0)
|
||
#endif
|
||
|
||
(Contributed by Victor Stinner in :issue:`39573`.)
|
||
|
||
* Calling :c:func:`PyDict_GetItem` without :term:`GIL` held had been allowed
|
||
for historical reason. It is no longer allowed.
|
||
(Contributed by Victor Stinner in :issue:`40839`.)
|
||
|
||
* ``PyUnicode_FromUnicode(NULL, size)`` and ``PyUnicode_FromStringAndSize(NULL, size)``
|
||
raise ``DeprecationWarning`` now. Use :c:func:`PyUnicode_New` to allocate
|
||
Unicode object without initial data.
|
||
(Contributed by Inada Naoki in :issue:`36346`.)
|
||
|
||
* The private ``_PyUnicode_Name_CAPI`` structure of the PyCapsule API
|
||
``unicodedata.ucnhash_CAPI`` has been moved to the internal C API.
|
||
(Contributed by Victor Stinner in :issue:`42157`.)
|
||
|
||
* :c:func:`Py_GetPath`, :c:func:`Py_GetPrefix`, :c:func:`Py_GetExecPrefix`,
|
||
:c:func:`Py_GetProgramFullPath`, :c:func:`Py_GetPythonHome` and
|
||
:c:func:`Py_GetProgramName` functions now return ``NULL`` if called before
|
||
:c:func:`Py_Initialize` (before Python is initialized). Use the new
|
||
:ref:`init-config` API to get the :ref:`init-path-config`.
|
||
(Contributed by Victor Stinner in :issue:`42260`.)
|
||
|
||
* :c:func:`PyList_SET_ITEM`, :c:func:`PyTuple_SET_ITEM` and
|
||
:c:func:`PyCell_SET` macros can no longer be used as l-value or r-value.
|
||
For example, ``x = PyList_SET_ITEM(a, b, c)`` and
|
||
``PyList_SET_ITEM(a, b, c) = x`` now fail with a compiler error. It prevents
|
||
bugs like ``if (PyList_SET_ITEM (a, b, c) < 0) ...`` test.
|
||
(Contributed by Zackery Spytz and Victor Stinner in :issue:`30459`.)
|
||
|
||
* The non-limited API files ``odictobject.h``, ``parser_interface.h``,
|
||
``picklebufobject.h``, ``pyarena.h``, ``pyctype.h``, ``pydebug.h``,
|
||
``pyfpe.h``, and ``pytime.h`` have been moved to the ``Include/cpython``
|
||
directory. These files must not be included directly, as they are already
|
||
included in ``Python.h``; see :ref:`api-includes`. If they have
|
||
been included directly, consider including ``Python.h`` instead.
|
||
(Contributed by Nicholas Sim in :issue:`35134`.)
|
||
|
||
* Use the :c:macro:`Py_TPFLAGS_IMMUTABLETYPE` type flag to create immutable type
|
||
objects. Do not rely on :c:macro:`Py_TPFLAGS_HEAPTYPE` to decide if a type
|
||
object is mutable or not; check if :c:macro:`Py_TPFLAGS_IMMUTABLETYPE` is set
|
||
instead.
|
||
(Contributed by Victor Stinner and Erlend E. Aasland in :issue:`43908`.)
|
||
|
||
* The undocumented function ``Py_FrozenMain`` has been removed from the
|
||
limited API. The function is mainly useful for custom builds of Python.
|
||
(Contributed by Petr Viktorin in :issue:`26241`.)
|
||
|
||
Deprecated
|
||
----------
|
||
|
||
* The ``PyUnicode_InternImmortal()`` function is now deprecated
|
||
and will be removed in Python 3.12: use :c:func:`PyUnicode_InternInPlace`
|
||
instead.
|
||
(Contributed by Victor Stinner in :issue:`41692`.)
|
||
|
||
Removed
|
||
-------
|
||
|
||
* Removed ``Py_UNICODE_str*`` functions manipulating ``Py_UNICODE*`` strings.
|
||
(Contributed by Inada Naoki in :issue:`41123`.)
|
||
|
||
* ``Py_UNICODE_strlen``: use :c:func:`PyUnicode_GetLength` or
|
||
:c:macro:`PyUnicode_GET_LENGTH`
|
||
* ``Py_UNICODE_strcat``: use :c:func:`PyUnicode_CopyCharacters` or
|
||
:c:func:`PyUnicode_FromFormat`
|
||
* ``Py_UNICODE_strcpy``, ``Py_UNICODE_strncpy``: use
|
||
:c:func:`PyUnicode_CopyCharacters` or :c:func:`PyUnicode_Substring`
|
||
* ``Py_UNICODE_strcmp``: use :c:func:`PyUnicode_Compare`
|
||
* ``Py_UNICODE_strncmp``: use :c:func:`PyUnicode_Tailmatch`
|
||
* ``Py_UNICODE_strchr``, ``Py_UNICODE_strrchr``: use
|
||
:c:func:`PyUnicode_FindChar`
|
||
|
||
* Removed ``PyUnicode_GetMax()``. Please migrate to new (:pep:`393`) APIs.
|
||
(Contributed by Inada Naoki in :issue:`41103`.)
|
||
|
||
* Removed ``PyLong_FromUnicode()``. Please migrate to :c:func:`PyLong_FromUnicodeObject`.
|
||
(Contributed by Inada Naoki in :issue:`41103`.)
|
||
|
||
* Removed ``PyUnicode_AsUnicodeCopy()``. Please use :c:func:`PyUnicode_AsUCS4Copy` or
|
||
:c:func:`PyUnicode_AsWideCharString`
|
||
(Contributed by Inada Naoki in :issue:`41103`.)
|
||
|
||
* Removed ``_Py_CheckRecursionLimit`` variable: it has been replaced by
|
||
``ceval.recursion_limit`` of the :c:type:`PyInterpreterState` structure.
|
||
(Contributed by Victor Stinner in :issue:`41834`.)
|
||
|
||
* Removed undocumented macros ``Py_ALLOW_RECURSION`` and
|
||
``Py_END_ALLOW_RECURSION`` and the ``recursion_critical`` field of the
|
||
:c:type:`PyInterpreterState` structure.
|
||
(Contributed by Serhiy Storchaka in :issue:`41936`.)
|
||
|
||
* Removed the undocumented ``PyOS_InitInterrupts()`` function. Initializing
|
||
Python already implicitly installs signal handlers: see
|
||
:c:member:`PyConfig.install_signal_handlers`.
|
||
(Contributed by Victor Stinner in :issue:`41713`.)
|
||
|
||
* Remove the ``PyAST_Validate()`` function. It is no longer possible to build a
|
||
AST object (``mod_ty`` type) with the public C API. The function was already
|
||
excluded from the limited C API (:pep:`384`).
|
||
(Contributed by Victor Stinner in :issue:`43244`.)
|
||
|
||
* Remove the ``symtable.h`` header file and the undocumented functions:
|
||
|
||
* ``PyST_GetScope()``
|
||
* ``PySymtable_Build()``
|
||
* ``PySymtable_BuildObject()``
|
||
* ``PySymtable_Free()``
|
||
* ``Py_SymtableString()``
|
||
* ``Py_SymtableStringObject()``
|
||
|
||
The ``Py_SymtableString()`` function was part the stable ABI by mistake but
|
||
it could not be used, because the ``symtable.h`` header file was excluded
|
||
from the limited C API.
|
||
|
||
Use Python :mod:`symtable` module instead.
|
||
(Contributed by Victor Stinner in :issue:`43244`.)
|
||
|
||
* Remove :c:func:`PyOS_ReadlineFunctionPointer` from the limited C API headers
|
||
and from ``python3.dll``, the library that provides the stable ABI on
|
||
Windows. Since the function takes a ``FILE*`` argument, its ABI stability
|
||
cannot be guaranteed.
|
||
(Contributed by Petr Viktorin in :issue:`43868`.)
|
||
|
||
* Remove ``ast.h``, ``asdl.h``, and ``Python-ast.h`` header files.
|
||
These functions were undocumented and excluded from the limited C API.
|
||
Most names defined by these header files were not prefixed by ``Py`` and so
|
||
could create names conflicts. For example, ``Python-ast.h`` defined a
|
||
``Yield`` macro which was conflict with the ``Yield`` name used by the
|
||
Windows ``<winbase.h>`` header. Use the Python :mod:`ast` module instead.
|
||
(Contributed by Victor Stinner in :issue:`43244`.)
|
||
|
||
* Remove the compiler and parser functions using ``struct _mod`` type, because
|
||
the public AST C API was removed:
|
||
|
||
* ``PyAST_Compile()``
|
||
* ``PyAST_CompileEx()``
|
||
* ``PyAST_CompileObject()``
|
||
* ``PyFuture_FromAST()``
|
||
* ``PyFuture_FromASTObject()``
|
||
* ``PyParser_ASTFromFile()``
|
||
* ``PyParser_ASTFromFileObject()``
|
||
* ``PyParser_ASTFromFilename()``
|
||
* ``PyParser_ASTFromString()``
|
||
* ``PyParser_ASTFromStringObject()``
|
||
|
||
These functions were undocumented and excluded from the limited C API.
|
||
(Contributed by Victor Stinner in :issue:`43244`.)
|
||
|
||
* Remove the ``pyarena.h`` header file with functions:
|
||
|
||
* ``PyArena_New()``
|
||
* ``PyArena_Free()``
|
||
* ``PyArena_Malloc()``
|
||
* ``PyArena_AddPyObject()``
|
||
|
||
These functions were undocumented, excluded from the limited C API, and were
|
||
only used internally by the compiler.
|
||
(Contributed by Victor Stinner in :issue:`43244`.)
|
||
|
||
* The ``PyThreadState.use_tracing`` member has been removed to optimize Python.
|
||
(Contributed by Mark Shannon in :issue:`43760`.)
|
||
|
||
|
||
Notable security feature in 3.10.7
|
||
==================================
|
||
|
||
Converting between :class:`int` and :class:`str` in bases other than 2
|
||
(binary), 4, 8 (octal), 16 (hexadecimal), or 32 such as base 10 (decimal)
|
||
now raises a :exc:`ValueError` if the number of digits in string form is
|
||
above a limit to avoid potential denial of service attacks due to the
|
||
algorithmic complexity. This is a mitigation for :cve:`2020-10735`.
|
||
This limit can be configured or disabled by environment variable, command
|
||
line flag, or :mod:`sys` APIs. See the :ref:`integer string conversion
|
||
length limitation <int_max_str_digits>` documentation. The default limit
|
||
is 4300 digits in string form.
|
||
|
||
Notable security feature in 3.10.8
|
||
==================================
|
||
|
||
The deprecated :mod:`!mailcap` module now refuses to inject unsafe text
|
||
(filenames, MIME types, parameters) into shell commands. Instead of using such
|
||
text, it will warn and act as if a match was not found (or for test commands,
|
||
as if the test failed).
|
||
(Contributed by Petr Viktorin in :gh:`98966`.)
|
||
|
||
Notable changes in 3.10.12
|
||
==========================
|
||
|
||
tarfile
|
||
-------
|
||
|
||
* The extraction methods in :mod:`tarfile`, and :func:`shutil.unpack_archive`,
|
||
have a new a *filter* argument that allows limiting tar features than may be
|
||
surprising or dangerous, such as creating files outside the destination
|
||
directory.
|
||
See :ref:`tarfile-extraction-filter` for details.
|
||
In Python 3.12, use without the *filter* argument will show a
|
||
:exc:`DeprecationWarning`.
|
||
In Python 3.14, the default will switch to ``'data'``.
|
||
(Contributed by Petr Viktorin in :pep:`706`.)
|