Python 3.8.2 final
Core and Builtins
bpo-39382: Fix a use-after-free in the single inheritance path of issubclass(), when the __bases__ of an object has a single reference, and so does its first item. Patch by Yonatan Goldschmidt.
bpo-39427: Document all possibilities for the -X options in the command line help section. Patch by Pablo Galindo.
Library
bpo-39649: Remove obsolete check for __args__ in bdb.Bdb.format_stack_entry.
bpo-39681: Fix a regression where the C pickle module wouldn’t allow unpickling from a file-like object that doesn’t expose a readinto() method.
bpo-39546: Fix a regression in ArgumentParser where allow_abbrev=False was ignored for long options that used a prefix character other than “-“.
bpo-39432: Implement PEP-489 algorithm for non-ascii “PyInit_…” symbol names in distutils to make it export the correct init symbol also on Windows.
Documentation
bpo-17422: The language reference now specifies restrictions on class namespaces. Adapted from a patch by Ethan Furman.
bpo-39572: Updated documentation of total flag of TypeDict.
bpo-39654: In pyclbr doc, update ‘class’ to ‘module’ where appropriate and add readmodule comment. Patch by Hakan Çelik.
IDLE
bpo-39663: Add tests for pyparse find_good_parse_start().
Python 3.8.1 is the first maintenance release of Python 3.8. The Python 3.8 series is the newest feature release of the Python language, and it contains many new features and optimizations.
Major new features of the 3.8 series, compared to 3.7
PEP 572, Assignment expressions
PEP 570, Positional-only arguments
PEP 587, Python Initialization Configuration (improved embedding)
PEP 590, Vectorcall: a fast calling protocol for CPython
PEP 578, Runtime audit hooks
PEP 574, Pickle protocol 5 with out-of-band data
Typing-related: PEP 591 (Final qualifier), PEP 586 (Literal types), and PEP 589 (TypedDict)
Parallel filesystem cache for compiled bytecode
Debug builds share ABI as release builds
f-strings support a handy = specifier for debugging
continue is now legal in finally: blocks
on Windows, the default asyncio event loop is now ProactorEventLoop
on macOS, the spawn start method is now used by default in multiprocessing
multiprocessing can now use shared memory segments to avoid pickling costs between processes
typed_ast is merged back to CPython
LOAD_GLOBAL is now 40% faster
pickle now uses Protocol 4 by default, improving performance
