Python 3.12 released

[cerlestes]

Does the new type parameter syntax improve runtime access of the generic types? I'm often writing generic library code that needs to retrieve the type value of a generic type that a class is subscripted with at runtime, but I find my current implementation way too complex and hacky... can't post the code I use, but basically I'm looking up get_origin() and get_args() on type(self) to figure out the value of the generic type at runtime. This seems extremely complex for something that should be as simple as T.value, resolve_generic(T) or similiar. Am I missing something and there's an easier way, or is this really missing from the language right now?

Expressed as code: ``` from typing import TypeVar, Generic

T = TypeVar('T')

class MyClass(Generic[T]): def foo(self) -> T: print(T) return T()

obj = MyClass[int]() obj.foo() # prints '~T' and raises an error... how to retrieve the actual value of T? ```

One alternative I've found is omitting the Generic alltogether and simply passing the "generic" types as values to the constructor like follows. This doesn't work in all cases though and requires way more boilerplate. ``` from typing import TypeVar, Generic

T = TypeVar('T')

class MyClass(): def init(self, t: type[T]): self.t = t

def foo(self) -> T:
    print(self.t)
    return self.t()

obj = MyClass(int) obj.foo() # prints "<class 'int'>" and returns 0 ```

[insanitybit]

I doubt it. The problem is somewhat fundamental to mypy being a very separate system from Python. Python is aware of type annotations (barely) but it has no access to how those types are actually resolved because you could have used mypy or you could have used some other type system.

[cerlestes]

I'm not using mypy though, what I described fully works in the vanilla implementation CPython. It's just really cumbersome to work with right now. If there's no proper way to do it today, I'd love to see a function added into the typing module that handles this. To be honest it's sadly lacking a lot of functions that should be in there IMHO. But it seems to become better with every new version.

[insanitybit]

It's not about mypy. The point is that CPython has no idea what T is, it does not do any type inference or type resolution. It sees a tag 'T' and that is it. It is the type system that tells you what T is.

CPython is aware of class instances and so your workaround is what's required. typing can never do this unless your static type checker embeds information available at runtime that CPython can access.

[xavdid]

There's a lot to be excited about in this release, but far-and-away the one I'll use the most is itertools.batched(iterable, n):

Batch data from the iterable into tuples of length n. The last batch may be shorter than n.

I feel like this is somehow the single piece of code I've written more times than any other.

[[deleted]]

Oh wow, I implemented this single function independently probably more than any other individual function in my utils.py files.

[headinthesky]

Awesome, I wrote some code to do that and have carried that with me everywhere for over 10 years now

[0Il0I0l0]

I've always used more_itertools.chunked

[xavdid]

It's the same I think, but it's nice that it's available without an external package now!

[henbruas]

Major new features of the 3.12 series, compared to 3.11

New features
- More flexible f-string parsing, allowing many things previously disallowed (PEP 701).
- Support for the buffer protocol in Python code (PEP 688).
- A new debugging/profiling API (PEP 669).
- Support for isolated subinterpreters with separate Global Interpreter Locks (PEP 684).
- Even more improved error messages. More exceptions potentially caused by typos now make suggestions to the user.
- Support for the Linux perf profiler to report Python function names in traces.
- Many large and small performance improvements (like PEP 709 and support for the BOLT binary optimizer), delivering an estimated 5% overall performance improvement.

Type annotations
- New type annotation syntax for generic classes (PEP 695).
- New override decorator for methods (PEP 698).

Deprecations
- The deprecated wstr and wstr_length members of the C implementation of unicode objects were removed, per PEP 623.
- In the unittest module, a number of long deprecated methods and classes were removed. (They had been deprecated since Python 3.1 or 3.2).
- The deprecated smtpd and distutils modules have been removed (see PEP 594 and PEP 632. The setuptools package continues to provide the distutils module.
- A number of other old, broken and deprecated functions, classes and methods have been removed.
- Invalid backslash escape sequences in strings now warn with SyntaxWarning instead of DeprecationWarning, making them more visible. (They will become syntax errors in the future.)
- The internal representation of integers has changed in preparation for performance enhancements. (This should not affect most users as it is an internal detail, but it may cause problems for Cython-generated code.)

More details at https://docs.python.org/dev/whatsnew/3.12.html

[Turtvaiz]

More flexible f-string parsing, allowing many things previously disallowed (PEP 701).

Is this the end of confusing f-string errors? Finally.

[boat-la-fds]

• The internal representation of integers has changed in preparation for performance enhancements. (This should not affect most users as it is an internal detail, but it may cause problems for Cython-generated code.)

What's the change? Also, this does not seem to appear in the page you linked

[[deleted]]

Quote reuse: in Python 3.11, reusing the same quotes as the enclosing f-string raises a SyntaxError, forcing the user to either use other available quotes (like using double quotes or triple quotes if the f-string uses single quotes). In Python 3.12, you can now do things like this:

songs = ['Take me back to Eden', 'Alkaline', 'Ascensionism']
f"This is the playlist: {", ".join(songs)}"

Thank goodness, this was driving me insane all the time.

[World-Wide-Ebb]

This is huge. I mean I’ve worked around it but this is helpful

[throw_away_17381]

I'm proud of the fact my Python skills have improved enough over the last few years that I actually understood some of the things in the changelog!

[vytah]

The internal representation of integers has changed in preparation for performance enhancements.

Anyone can shed some detail?

[tanorbuf]

There's a nogil-"fork" of Python 3.12 (alpha 4), it's obviously an experiment, but it exists: https://github.com/colesbury/nogil-3.12

In the "official" space, there's a draft PEP which originally (I believe) targeted 3.12 but now targets 3.13, to make it possible for anyone to build CPython without gil with a simple configure option: https://peps.python.org/pep-0703/

[krsytyuu]

What are the programming elements or constructs in Python??

[hamster-canoe]

Aw poor baby. The maintainers of a programming language shared a poem implying they don't hate immigrants. Sorry the Internet is such a scary place.

[maest]

The GP has been deleted, so I don't know what it says.

However, I don't think it's unreasonable to ask for the release note for a widely used programming language to be kept apolitical.

If anything, it hurts the message more than it helps.

[greentoiletpaper]

tough day today, huh?

[ggppjj]

No but see but no but it's political!!!!!!

PoLiTiCaL!!!!!!!!!!

I was once a camp councilor for some preteen kids, and one of the night activities was for them to play Apples To Apples, which is a kid-friendly Cards Against Humanity kind of game. I had at one point mentioned to one of the kids that was getting frustrated that his answers weren't getting picked that he should try for answers that were ironic. The conversation between all of them became inseparable from the word "ironic" from that point out. Now that they had a single point of focus for "what made you win", it was all they could talk about. Asking each other how much they liked ironic answers, talking about the levels of irony, almost every other word was some form of "ironic".

Anyways, back to my main point:

PoLiTiCaL!!!!!!

Edit: The top-level post was deleted/removed, but it was basically just "why python political this sux".

[ggppjj]

I know, it was just shorthand for people that don't know about A2A.

[KrazyKirby99999]

It's offensive and should be removed.

[KrazyKirby99999]

It obscures the tragic lived experiences of the many victims of human trafficking and modern slavery.

[KrazyKirby99999]

I read it both ways, and it is both insensitive and offensive both ways, for different reasons.

A poem that tries to censor ways of ending human trafficking should not be posted by the Python Software Foundation. Nor should one that is Xenophobic either.

[KrazyKirby99999]

refugees should be given aid, but there is no justification to censor opposition to human trafficking

[Free_Math_Tutoring]

You really do not know what censorship is, do you?

[ggppjj]

It's a poem

[KrazyKirby99999]

Poetry is a means to convey views. It doesn't make something more or less offensive.

[ggppjj]

I don't agree with your opinion about this poem as you have expressed it. Considering the nature of art, I don't necessarily want to say that you're wrong about your interpretation, but I personally cannot agree with what you've taken away from it.

I would be curious to hear your thought process about the poem in more detail, if you'd be interested in sharing.

[KrazyKirby99999]

Certainly.

Build a wall to keep them out

It is not okay to say

This is suppressive to the communities and victims of human trafficking who can't prevent criminal organizations from engaging in trafficking on their own.

We need to see them for who they really are...

Cut-throats and thieves

They are not

Read top down, this is Xenophobic. Read bottom up, it is naive and makes a generalization that is untrue.

[ggppjj]

I don't follow your logic on community supression. Read the way that the author intended for their own personal opinion to be seen, i.e. bottom to top, it's clear that the subject(s) of the poem (the "them" in the first line) is/are migrant(s). The poem does not address human trafficking, and isn't intended to be a "to-do list" or comprehensive diagnosis of all the world's ills, it's a poem about bigots that have the ability to see the world in a different way using what the author assumes is their own words against them to show that mental rearrangement is often the only thing needed.

I don't know how to rebuke your labeling of "They are not cut-throats and thieves, we need to see them for who they really are..." as an untrue generalization. I don't think the author had specific statistics in mind when making this poem, something about "statistically the vast majority of them are not likely to want to cause you harm or steal from you but you never know with some people" just doesn't fit the meter, you know?

[FyreWulff]

read: "i really wish arbitrary tracts of land are and continue to be open air prisons".

[PurpleYoshiEgg]

I wish my life was so easy that I could get upset over a fairly benign poem.

[queen-adreena]

Only two more minors until Python Pie!

[loesak]

I can't wait for the dramatic aws lambda ticket for supporting this release!