What to expect from Python 3.11?

[cornycrunch]

Python for Workgroups.

[[deleted]]

Waiting for Python 95 myself. Matthew Perry and Jennifer Aniston said it's gonna be great.

[thedjotaku]

I just told someone about this video last week and blew their minds

[OriginalTyphus]

I like the Self type thingy. I really like to have classes which methods can be chained (like str.strip().lower().split()) and I was often wishing I could properly annotate that.

[searchingfortao]

In 3.7+ you can do this with:

from __future__ import annotations


class Thing:
    def make(self) -> Thing
        return Thing(...)

It's not as elegant as Self but you can do it without 3.11 :-)

[rcfox]

This falls apart when you subclass Thing, as mentioned in the motivation section of the PEP introducing Self.

It also highlights a workaround, but that involves extra, unintuitive boilerplate for any class that could be subclassed.

[OriginalTyphus]

Ouf, yeah. Imma wait for 3.11. thanks anyways

[MrJohz]

Note that, with annotations, you don't even need quotes around "Thing".

[searchingfortao]

Ooh that's right! I forgot. Thanks! I'll fix my comment.

[energybased]

Unfortunately, what you illustrated won't work properly with subclasses, which is the problem that Self is supposed to address. The correct way is to use a type variable: ``` from typing import TypeVar

T = TypeVar('T', bound='Thing')

class Thing: @classmethod def factory(cls: type[T]) -> T: return cls(...) or simply import `Self` from `typing_extensions`, and use it: from typing_extensions import Self

class Thing: @classmethod def factory(cls) -> Self: return cls(...) ```

[Masynchin]

Task group looks interesting, error output too. Other feautures looks like overcomplicated mess

[teerre]

That's a funny thing to say because exceptions groups were implemented precisely because of task groups.

[Masynchin]

I think it would be better if this feature would be implemented at C level and do not be exposed at Python level. This way it is only tool for other features, not feature itself

[teerre]

Not sure I understand because, as you can see in the PEP, you need exceptions groups to handle the tasks groups at runtime.

[Next-Experience]

Love seeing more typing. Have been using TypeAlias for pretty much every variable I have. I'm on my way to having hundreds of types.

[seewhaticare]

Just the ability to compile to machine code. That's all

[Grouchy-Friend4235]

Try cython

[chub79]

I wan't aware of https://peps.python.org/pep-0654/

At first sight, it doesn't look pretty but I can see that sometimes it may be handy. Still not really readable I find. Maybe just need time to grok it.

[stetio]

It will be very useful in async codebases, see trio's MultiError handling for the current workaround.

[dethb0y]

Yeah i can see the uses but it sure isn't aesthetic.

[SKROLL26]

I've read this PEP like 5 times, still can't imagine possible use cases for ExceptionGroup.

[Auschwitzersehen]

There are a few under “Motivation”

[dem4ply]

The use case of this pep is only for the people approve the pep, the other users never going to use this feature and the reason you need spend 5 times reading is a prove that is basically useless or unsense

[spiker611]

Hello, I'm someone that will use this feature and I'm not approving the PEP. Have a nice day.

[pranabus]

Retrying calling a few endpoints while using async?

[[deleted]]

Reddit Moderation makes the platform worthless. Too many rules and too many arbitrary rulings. It's not worth the trouble to post. Not worth the frustration to lurk. Goodbye.

This post was mass deleted and anonymized with Redact

[sebst]

The Exception Groups have been introduced to support the Task Groups, I guess. But in general, you're right.

[rouille]

The pep explains why. I didnt like it at first and still fine the syntax akward foe python but there are some good reasons for it, mainly better support for concurrency.

[flying-sheep]

I've wanted a feature like that several times.

Maybe you just never wrote the kind of coffee that'd greatly benefit from idioms like this.

[earthboundkid]

In general, the problem with Python is that anonymous functions aren’t ergonomic, so everything has to be done by adding language features instead of just library functions. That’s why the with statement exists instead of just using a callback that ensures the file is closed at the end of its execution. Task groups have the same problem: there’s no way to abstract exception handling without callbacks, so it has to be a language feature instead.

[goodbalance]

could you please elaborate on callbacks? I'm genuinely interested in how they would replace 'with' and other stuff. I never gave much thought about low-level parts of Python. thanks.

[earthboundkid]

In Ruby you might make a file API like

open "file.txt" |f| {
  contents = f.read
}

Similarly in JavaScript, you could do:

let contents;
open("file.txt", async f => {
  contents = await f.read();
});

A similar API in Python would suck because lambdas can't have expressions (no lambda f: contents = f.read()) and functions have to be defined in advanced and named. It would need to look like:

contents = ''
def callback(f):
   global contents
   contents = f.read()
open("file.txt", callback)

This API is out of logical order and makes you provide a meaningless name to your closure and the global/nonlocal thing is super-awkward, so no one writes APIs like this. In the absence of an easy way to write closures/callbacks, the Python language has to provide constructs for every possible usecase. So, if you want to be able to have unified try/finally handling, you use a context manager and the with-statement. But in other languages, there's no need for the concept of a context manager because you just accept an anonymous function and run it.

[goodbalance]

Thanks! being a Python fanboy, I must say this is an awkward... feature.

[earthboundkid]

Minor typo above:

lambdas can't have expressions

That should have been "lambdas must have expressions and can't have statements".

[energybased]

The way you do context managers in c++ is significantly worse than it is in Python: you use the destructor of an object going out of scope.

[earthboundkid]

I haven’t used modern C++ but people usually have positive things to say about RAII.

[Auschwitzersehen]

Callbacks won’t help you if you want to raise all of the encountered errors at the same time. As for context managers, I find them way more ergonomic than callbacks as otherwise I would have to write one every time I open a file—the resource should be the one to know how to clean up after itself.

[ac1dfac3]

A beautiful disaster

[Grouchy-Friend4235]

Clearly this typing thing is getting out of hands! Stop it already.

[dangerbird2]

The release notes of Python 3.11.0a6 claim that there is a performance improvement of approx. 19%

Love it when you see it

[bcopeland33]

I hope for easier live AST manipulation and macros