Good things in Python versions

This is a HIGHLY subjective list of new features that I personally find useful when porting programs and libraries to newer versions of Python.

Let me say that again: this list is HIGHLY subjective. Pinch of salt, YMMV, etc.

Python 3.7

• Base
  • deferred annotations
  • async and await are reserved keywords
  • dict is ordered (insertion order)
• asyncio
  • added asyncio.run() and asyncio.create_task(), as well as a slew of others
• dataclasses
  • it exists!
• datetime
  • added datetime.fromisoformat()
• functools
  • type-based functools.singledispatch()
• hmac
  • added hmac.digest()
• importlib.resources
  • it exists!
• io
  • added TextIOWrapper.reconfigure()
• socket
  • added socket.close()
• subprocess
  • added subprocess.run(capture_output=True)

Python 3.8

• Base
  • assignment expressions
  • positional-only parameters
  • {expr=...} in f-strings
  • pickle protocol 5
  • \N{name} in regular expressions
• asyncio
  • named tasks
• functools
  • functools.lru_cache without parentheses
  • added functools.cached_property()
  • added functools.singledispatchmethod()
• importlib.metadata
  • it exists!
• pathlib
  • added Path.link_to(), but see Path.hardlink_to() in 3.10
• shlex
  • added shlex.join()
• typing
  • added Final, Literal, Protocol, and TypedDict
  • added typing.get_origin() and typing.get_args()

Python 3.9

• Base
  • union operators for dict (dict_a | dict_b, dict_a |= dict_b)
  • dict, list, etc. can now be used as typing generics
  • added str.removeprefix() and str.removesuffix()
  • added typing annotations
  • __file__ is now an absolute path
• asyncio
  • added PidfdChildWatcher
• collections.abc
  • subscriptable Callable, Generator, Iterable, Iterator, etc.
• ipaddress
  • scoped IPv6 addresses
• os
  • added os.pidfd_open() for Linux 5.3+
  • added os.waitstatus_to_exitcode()
• pathlib
  • added Path.readlink()
• random
  • added random.randbytes()
• socket
  • added socket.send_fds() and socket.recv_fds()
• typing
  • added Annotated and typing.get_type_hints(include_extras=True)

Python 3.10

• Base
  • structural pattern matching
  • parenthesized contexts
  • write union types as X | Y
  • added TypeAlias and ParamSpec
  • added aiter() and anext()
• dataclasses
  • keyword-only fields (kw_only=True)
• os
  • added os.eventfd() and os.splice()
• pathlib
  • added Path.hardlink_to() and deprecate Path.link_to()
• socket
  • socket.timeout is now a TimeoutError

Python 3.11

• Base
  • exception groups
  • starred expressions in for statements
  • exc_type and exc_traceback dropped from exc_info
• asyncio
  • datagram functions
  • start_tls()
  • timeout()
• contextlib
  • chdir()
• datetime
  • UTC
• enum
  • StrEnum! ReprEnum!
• functools
  • type-based singledispatch() understands unions now
• operator
  • call()
• time
  • time.sleep() with nanosecond resolution
• tomllib
  • it exists!
• typing
  • assert_never(), assert_type(), reveal_type()
  • dataclass_transform?
  • LiteralString
  • Self! Self! Self!
  • TypeVarTuple?
  • TypedDict: Required/NotRequired
  • Any can now be subclassed?

Python 3.12

• f-strings containing any Python expression
• PEP 695 type parameters (is this Rust?)
• PEP 692 TypedDict for kwargs
• PEP 698 override decorator
• asyncio
  • see what eager_task_factory() is all about, maybe pass it to run() as a task factory
• configparser
  • ConfigParser.readfp() is removed, use readfile() instead
• datetime
  • utcnow() and utcfromtimestamp() are deprecated; use now() and fromtimestamp() passing tz=datetime.UTC instead
• functools
  • cached_property() no longer locks, let's hope we don't use it anyway
• importlib
  • removed some deprecated methods; needs further looking into
• itertools
  • itertools.batched()
• json
  • AttrDict
• pathlib
  • derived classes... can I use this somehow?
  • walk()
  • relative_to(..., walk_up)
  • case_sensitive for glob() and friends
• shutil
  • make_archive(..., root_dir)
• sys
  • last_exc for debugging, e.g. in the REPL
• tarfile
  • extract filters
• tempfile
  • NamedTemporaryFile(..., delete_on_close=True)
• unittest
  • the long-deprecated methods are finally removed
• uuid
  • command-line interface

Python 3.13

• asyncio
  • loop.create_unix_server() automatically removes the socket
• copy
  • replace()
• ipaddress
  • IPv4Address.ipv6_mapped
• os
  • process_cpu_count()
• pathlib
  • Path.from_uri()
  • PurePath.full_match()
• re
  • PatternError (renamed from re.error)
• traceback
  • exc_type is deprecated
• typing
  • get_protocol_members()
  • is_protocol()