Quick summary
Summarize this blog with AI
Historical archive: Python 3.12.0 was released on October 2, 2023. This page describes that release, not the latest Python version. An earlier version of this article included unsupported feature predictions and PEP numbers; this corrected account uses the official release record and accepted proposals.
The release and its date
The Python 3.12.0 release page establishes the release date. Use it as a historical source, not as advice to install the initial patch release today. Select a currently maintained version and patch level appropriate to your dependencies when starting a new project.
Two syntax changes you can run
PEP 695 introduced type-parameter syntax and the type alias statement. Type annotations describe intended types to tooling; they do not automatically validate every argument at runtime. PEP 701 formalized f-string parsing and allowed expressions to reuse the surrounding quote style.
# Requires Python 3.12 or later.
type Sale = tuple[str, int]
def first[T](values: list[T]) -> T:
if not values:
raise ValueError("values must not be empty")
return values[0]
sale: Sale = ("book", 3)
assert first([sale]) == ("book", 3)
order = {"item": "book"}
message = f"Item: {order["item"]}"
assert message == "Item: book"
print(message)The output is Item: book. This example was executed on Python 3.12.14. On an older interpreter, the new syntax is not accepted; check the interpreter before diagnosing the code. The empty-list guard is explicit application logic, not enforcement supplied by the type annotation.
Other real proposals in the 3.12 release
| Proposal | What changed | Limit to remember |
|---|---|---|
| PEP 684 | A per-interpreter GIL for configured subinterpreters | This was a C-API capability in 3.12, not a claim that ordinary Python threads automatically run CPU-bound code in parallel. |
| PEP 669 | Low-impact monitoring support for tools | A tooling interface, not a new user-facing profiler that measures your program automatically. |
| PEP 709 | Inlined comprehensions | Do not turn an implementation optimization into an unmeasured speedup guarantee for a whole application. |
Check removals as well as new features
The Python 3.12 change notes document removal of the standard-library distutils package, removal of imp, and the fact that new venv environments no longer preinstall setuptools. A project that happened to rely on an implicitly installed packaging tool needs an explicit dependency or an updated build configuration.
Recreate your project environment with the target interpreter, install the reviewed dependencies, run the tests, and investigate each failure using its actual traceback. Keep an environment for the old supported version until migration checks pass. A clean install succeeding is only the start of compatibility testing.
Read the historical record without inventing news
This archive makes no claims about unverified community launches, future syntax, or October 2023 events beyond the cited release. To investigate another proposed language change, look up its actual number, title, status, and target version in the official PEP index. A proposal being discussed does not mean it shipped.
For installing project dependencies after choosing an interpreter, continue with pip and virtual environments.
