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diff --git a/docs/differences/python_39.rst b/docs/differences/python_39.rst new file mode 100644 index 000000000..6852dd635 --- /dev/null +++ b/docs/differences/python_39.rst @@ -0,0 +1,121 @@ +.. _python_39: + +Python 3.9 +========== + +Python 3.9.0 (final) was released on the 5th October 2020. The Features for 3.9 are +defined in `PEP 596 <https://www.python.org/dev/peps/pep-0596/#features-for-3-9>`_ +and a detailed description of the changes can be found in +`What's New in Python 3.9 <https://docs.python.org/3/whatsnew/3.9.html>`_ + + +--------------------------------------------------------+----------------------------------------------------+--------------+ + | **Features:** | | **Status** | + +--------------------------------------------------------+----------------------------------------------------+--------------+ + | `PEP 573 <https://www.python.org/dev/peps/pep-0573/>`_ | fast access to module state from methods of C | | + | | extension types | | + +--------------------------------------------------------+----------------------------------------------------+--------------+ + | `PEP 584 <https://www.python.org/dev/peps/pep-0584/>`_ | union operators added to dict | | + +--------------------------------------------------------+----------------------------------------------------+--------------+ + | `PEP 585 <https://www.python.org/dev/peps/pep-0584/>`_ | type hinting generics in standard collections | | + +--------------------------------------------------------+----------------------------------------------------+--------------+ + | `PEP 593 <https://www.python.org/dev/peps/pep-0593/>`_ | flexible function and variable annotations | | + +--------------------------------------------------------+----------------------------------------------------+--------------+ + | `PEP 602 <https://www.python.org/dev/peps/pep-0602/>`_ | CPython adopts an annual release cycle. Instead of | | + | | annual, aiming for two month release cycle | | + +--------------------------------------------------------+----------------------------------------------------+--------------+ + | `PEP 614 <https://www.python.org/dev/peps/pep-0614/>`_ | relaxed grammar restrictions on decorators | | + +--------------------------------------------------------+----------------------------------------------------+--------------+ + | `PEP 615 <https://www.python.org/dev/peps/pep-0615/>`_ | the IANA Time Zone Database is now present in the | | + | | standard library in the zoneinfo module | | + +--------------------------------------------------------+----------------------------------------------------+--------------+ + | `PEP 616 <https://www.python.org/dev/peps/pep-0616/>`_ | string methods to remove prefixes and suffixes | | + +--------------------------------------------------------+----------------------------------------------------+--------------+ + | `PEP 617 <https://www.python.org/dev/peps/pep-0617/>`_ | CPython now uses a new parser based on PEG | | + +--------------------------------------------------------+----------------------------------------------------+--------------+ + +Other Language Changes: + + +-------------------------------------------------------------------------------------------------------------+---------------+ + | *__import__()* now raises *ImportError* instead of *ValueError* | Completed | + +-------------------------------------------------------------------------------------------------------------+---------------+ + | Python now gets the absolute path of the script filename specified on the command line (ex: *python3* | | + | *script.py*): the *__file__* attribute of the *__main__* module became an absolute path, rather than a | | + | relative path | | + +-------------------------------------------------------------------------------------------------------------+---------------+ + | By default, for best performance, the errors argument is only checked at the first encoding/decoding error | | + | and the encoding argument is sometimes ignored for empty strings | | + +-------------------------------------------------------------------------------------------------------------+---------------+ + | *"".replace("", s, n)* now returns *s* instead of an empty string for all non-zero n. It is now consistent | | + | with *"".replace("", s)* | | + +-------------------------------------------------------------------------------------------------------------+---------------+ + | Any valid expression can now be used as a decorator. Previously, the grammar was much more restrictive | | + +-------------------------------------------------------------------------------------------------------------+---------------+ + | Parallel running of *aclose()* / *asend()* / *athrow()* is now prohibited, and *ag_running* now reflects | | + | the actual running status of the async generator | | + +-------------------------------------------------------------------------------------------------------------+---------------+ + | Unexpected errors in calling the *__iter__* method are no longer masked by TypeError in the in operator and | | + | functions contains(), indexOf() and countOf() of the operator module | | + +-------------------------------------------------------------------------------------------------------------+---------------+ + | Unparenthesized lambda expressions can no longer be the expression part in an if clause in comprehensions | | + | and generator expressions | | + +-------------------------------------------------------------------------------------------------------------+---------------+ + +Changes to built-in modules: + + +---------------------------------------------------------------------------------------------------------------+---------------+ + | `asyncio` | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | Due to significant security concerns, the reuse_address parameter of *asyncio.loop.create_datagram_endpoint()*| | + | is no longer supported | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | Added a new coroutine *shutdown_default_executor()* that schedules a shutdown for the default executor that | | + | waits on the *ThreadPoolExecutor* to finish closing. Also, *asyncio.run()* has been updated to use the new | | + | coroutine. | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | Added *asyncio.PidfdChildWatcher*, a Linux-specific child watcher implementation that polls process file | | + | descriptors | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | added a new *coroutine asyncio.to_thread()* | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | When cancelling the task due to a timeout, *asyncio.wait_for()* will now wait until the cancellation is | | + | complete also in the case when timeout is <= 0, like it does with positive timeouts | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | *asyncio* now raises *TyperError* when calling incompatible methods with an *ssl.SSLSocket* socket | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | `gc` | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | Garbage collection does not block on resurrected objects | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | Added a new function *gc.is_finalized()* to check if an object has been finalized by the garbage collector | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | `math` | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | Expanded the *math.gcd()* function to handle multiple arguments. Formerly, it only supported two arguments | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | Added *math.lcm()*: return the least common multiple of specified arguments | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | Added *math.nextafter()*: return the next floating-point value after x towards y | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | Added *math.ulp()*: return the value of the least significant bit of a float | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | `os` | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | Exposed the Linux-specific *os.pidfd_open()* and *os.P_PIDFD* | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | The *os.unsetenv()* function is now also available on Windows | Completed | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | The *os.putenv()* and *os.unsetenv()* functions are now always available | Completed | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | Added *os.waitstatus_to_exitcode()* function: convert a wait status to an exit code | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | `random` | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | Added a new *random.Random.randbytes* method: generate random bytes | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | `sys` | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | Added a new *sys.platlibdir* attribute: name of the platform-specific library directory | | + +---------------------------------------------------------------------------------------------------------------+---------------+ + | Previously, *sys.stderr* was block-buffered when non-interactive. Now stderr defaults to always being | | + | line-buffered | | + +---------------------------------------------------------------------------------------------------------------+---------------+ |