01953f2964
And how they relate to MicroPython. As these features are implemented (or the decision is made to not implement them) the tables can be updated to document the differences between MicroPython and standard Python.
122 lines
14 KiB
ReStructuredText
122 lines
14 KiB
ReStructuredText
.. _python_39:
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Python 3.9
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==========
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Python 3.9.0 (final) was released on the 5th October 2020. The Features for 3.9 are
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defined in `PEP 596 <https://www.python.org/dev/peps/pep-0596/#features-for-3-9>`_
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and a detailed description of the changes can be found in
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`What's New in Python 3.9 <https://docs.python.org/3/whatsnew/3.9.html>`_
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+--------------------------------------------------------+----------------------------------------------------+--------------+
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| **Features:** | | **Status** |
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+--------------------------------------------------------+----------------------------------------------------+--------------+
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| `PEP 573 <https://www.python.org/dev/peps/pep-0573/>`_ | fast access to module state from methods of C | |
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| | extension types | |
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+--------------------------------------------------------+----------------------------------------------------+--------------+
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| `PEP 584 <https://www.python.org/dev/peps/pep-0584/>`_ | union operators added to dict | |
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+--------------------------------------------------------+----------------------------------------------------+--------------+
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| `PEP 585 <https://www.python.org/dev/peps/pep-0584/>`_ | type hinting generics in standard collections | |
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+--------------------------------------------------------+----------------------------------------------------+--------------+
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| `PEP 593 <https://www.python.org/dev/peps/pep-0593/>`_ | flexible function and variable annotations | |
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+--------------------------------------------------------+----------------------------------------------------+--------------+
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| `PEP 602 <https://www.python.org/dev/peps/pep-0602/>`_ | CPython adopts an annual release cycle. Instead of | |
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| | annual, aiming for two month release cycle | |
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+--------------------------------------------------------+----------------------------------------------------+--------------+
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| `PEP 614 <https://www.python.org/dev/peps/pep-0614/>`_ | relaxed grammar restrictions on decorators | |
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+--------------------------------------------------------+----------------------------------------------------+--------------+
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| `PEP 615 <https://www.python.org/dev/peps/pep-0615/>`_ | the IANA Time Zone Database is now present in the | |
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| | standard library in the zoneinfo module | |
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+--------------------------------------------------------+----------------------------------------------------+--------------+
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| `PEP 616 <https://www.python.org/dev/peps/pep-0616/>`_ | string methods to remove prefixes and suffixes | |
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+--------------------------------------------------------+----------------------------------------------------+--------------+
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| `PEP 617 <https://www.python.org/dev/peps/pep-0617/>`_ | CPython now uses a new parser based on PEG | |
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+--------------------------------------------------------+----------------------------------------------------+--------------+
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Other Language Changes:
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+-------------------------------------------------------------------------------------------------------------+---------------+
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| *__import__()* now raises *ImportError* instead of *ValueError* | Completed |
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+-------------------------------------------------------------------------------------------------------------+---------------+
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| Python now gets the absolute path of the script filename specified on the command line (ex: *python3* | |
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| *script.py*): the *__file__* attribute of the *__main__* module became an absolute path, rather than a | |
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| relative path | |
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+-------------------------------------------------------------------------------------------------------------+---------------+
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| By default, for best performance, the errors argument is only checked at the first encoding/decoding error | |
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| and the encoding argument is sometimes ignored for empty strings | |
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+-------------------------------------------------------------------------------------------------------------+---------------+
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| *"".replace("", s, n)* now returns *s* instead of an empty string for all non-zero n. It is now consistent | |
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| with *"".replace("", s)* | |
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+-------------------------------------------------------------------------------------------------------------+---------------+
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| Any valid expression can now be used as a decorator. Previously, the grammar was much more restrictive | |
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+-------------------------------------------------------------------------------------------------------------+---------------+
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| Parallel running of *aclose()* / *asend()* / *athrow()* is now prohibited, and *ag_running* now reflects | |
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| the actual running status of the async generator | |
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+-------------------------------------------------------------------------------------------------------------+---------------+
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| Unexpected errors in calling the *__iter__* method are no longer masked by TypeError in the in operator and | |
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| functions contains(), indexOf() and countOf() of the operator module | |
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+-------------------------------------------------------------------------------------------------------------+---------------+
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| Unparenthesized lambda expressions can no longer be the expression part in an if clause in comprehensions | |
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| and generator expressions | |
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+-------------------------------------------------------------------------------------------------------------+---------------+
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Changes to built-in modules:
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| `asyncio` |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| Due to significant security concerns, the reuse_address parameter of *asyncio.loop.create_datagram_endpoint()*| |
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| is no longer supported | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| Added a new coroutine *shutdown_default_executor()* that schedules a shutdown for the default executor that | |
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| waits on the *ThreadPoolExecutor* to finish closing. Also, *asyncio.run()* has been updated to use the new | |
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| coroutine. | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| Added *asyncio.PidfdChildWatcher*, a Linux-specific child watcher implementation that polls process file | |
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| descriptors | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| added a new *coroutine asyncio.to_thread()* | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| When cancelling the task due to a timeout, *asyncio.wait_for()* will now wait until the cancellation is | |
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| complete also in the case when timeout is <= 0, like it does with positive timeouts | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| *asyncio* now raises *TyperError* when calling incompatible methods with an *ssl.SSLSocket* socket | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| `gc` |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| Garbage collection does not block on resurrected objects | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| Added a new function *gc.is_finalized()* to check if an object has been finalized by the garbage collector | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| `math` |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| Expanded the *math.gcd()* function to handle multiple arguments. Formerly, it only supported two arguments | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| Added *math.lcm()*: return the least common multiple of specified arguments | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| Added *math.nextafter()*: return the next floating-point value after x towards y | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| Added *math.ulp()*: return the value of the least significant bit of a float | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| `os` |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| Exposed the Linux-specific *os.pidfd_open()* and *os.P_PIDFD* | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| The *os.unsetenv()* function is now also available on Windows | Completed |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| The *os.putenv()* and *os.unsetenv()* functions are now always available | Completed |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| Added *os.waitstatus_to_exitcode()* function: convert a wait status to an exit code | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| `random` |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| Added a new *random.Random.randbytes* method: generate random bytes | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| `sys` |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| Added a new *sys.platlibdir* attribute: name of the platform-specific library directory | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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| Previously, *sys.stderr* was block-buffered when non-interactive. Now stderr defaults to always being | |
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| line-buffered | |
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+---------------------------------------------------------------------------------------------------------------+---------------+
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