Python 3.8¶
Python 3.8.0 (final) was released on the 14 October 2019. The Features for 3.8 are defined in PEP 569 and a detailed description of the changes can be found in What’s New in Python 3.8.
Features:
Status
Positional-only arguments
Assignment Expressions
Pickle protocol 5 with out-of-band data
Runtime audit hooks
Python Initialization Configuration
Vectorcall: a fast calling protocol for CPython
Miscellaneous
f-strings support = for self-documenting expressions and debugging
Completed
Other Language Changes:
A continue statement was illegal in the finally clause due to a problem with the implementation. In Python 3.8 this restriction was lifted
Completed
The bool, int , and fractions.Fraction types now have an as_integer_ratio() method like that found in float and decimal.Decimal
Constructors of int, float and complex will now use the __index__() special method, if available and the corresponding method __int__(), __float__() or __complex__() is not available
Added support of N{name} escapes in regular expressions
Dict and dictviews are now iterable in reversed insertion order using reversed()
The syntax allowed for keyword names in function calls was further restricted. In particular, f((keyword)=arg) is no longer allowed
Generalized iterable unpacking in yield and return statements no longer requires enclosing parentheses
When a comma is missed in code such as [(10, 20) (30, 40)], the compiler displays a SyntaxWarning with a helpful suggestion
Arithmetic operations between subclasses of datetime.date or datetime.datetime and datetime.timedelta objects now return an instance of the subclass, rather than the base class
When the Python interpreter is interrupted by Ctrl-C (SIGINT) and the resulting KeyboardInterrupt exception is not caught, the Python process now exits via a SIGINT signal or with the correct exit code such that the calling process can detect that it died due to a Ctrl-C
Some advanced styles of programming require updating the types.CodeType object for an existing function
For integers, the three-argument form of the pow() function now permits the exponent to be negative in the case where the base is relatively prime to the modulus
Dict comprehensions have been synced-up with dict literals so that the key is computed first and the value second
The object.__reduce__() method can now return a tuple from two to six elements long
Changes to built-in modules:
asyncio.run() has graduated from the provisional to stable API
Completed
Running python -m asyncio launches a natively async REPL
The exception asyncio.CancelledError now inherits from BaseException rather than Exception and no longer inherits from concurrent.futures.CancelledError
Completed
Added asyncio.Task.get_coro() for getting the wrapped coroutine within an asyncio.Task
Asyncio tasks can now be named, either by passing the name keyword argument to asyncio.create_task() or the create_task() event loop method, or by calling the set_name() method on the task object
Added support for Happy Eyeballs to asyncio.loop.create_connection(). To specify the behavior, two new parameters have been added: happy_eyeballs_delay and interleave.
get_objects() can now receive an optional generation parameter indicating a generation to get objects from. (Note, though, that while gc is a built-in, get_objects() is not implemented for MicroPython)
Added new function math.dist() for computing Euclidean distance between two points
Expanded the math.hypot() function to handle multiple dimensions
Added new function, math.prod(), as analogous function to sum() that returns the product of a “start” value (default: 1) times an iterable of numbers
Added two new combinatoric functions math.perm() and math.comb()
Added a new function math.isqrt() for computing accurate integer square roots without conversion to floating point
The function math.factorial() no longer accepts arguments that are not int-like
Completed
Add new sys.unraisablehook() function which can be overridden to control how “unraisable exceptions” are handled