Mailman 3 April 2023 - Python-Dev

Proposal: Allow non-default after default arguments
by Sebastian Rittau 16 Oct '23

16 Oct '23

Currently, Python doesn't allow non-default arguments after default arguments: >>> def foo(x=None, y): pass File "<stdin>", line 1 def foo(x=None, y): pass ^ SyntaxError: non-default argument follows default argument I believe that at the time this was introduced, no use cases for this were known and this is is supposed to prevent a source of bugs. I have two use cases for this, one fringe, but valid, the other more important: The fringe use case: Suppose you have a function that takes a 2D coordinate value as separate "x" and "y" arguments. The "x" argument is optional, the "y" argument isn't. Currently there are two ways to do this, none of them particularly great: def foo(y, x): # reverse x and y arguments, confusing ... def foo(x, y=None): # Treat the x argument as y if only one argument is provided if y is None: x, y = y, x ... To me, the "natural" solution looks like this: def foo(x=None, y): ... # Called like this: foo(1, 2) foo(y=2) This could also be useful when evolving APIs. For example there is a function "bar" that takes two required arguments. In a later version, the first argument gains a useful default, the second doesn't. There is no sensible way to evolve the API at the moment. The more important use case involves @overloads. A condensed example of a function where the return type depends on an "encoding" parameter, followed by further parameters that could be called like this: foo(123, "utf-8") # would return bytes foo(encoding="utf-8") foo(123, None) # would return str foo(encoding=None) foo(x=123) # would return str foo() This could ideally be written as: @overload def foo(x: int = ..., encoding: None = ...) -> str: ... @overload def foo(x: int = ..., encoding: str) -> bytes: ... # plus the actual implementation But due to the syntax constraint, this needs to be hacked around with a third overload: @overload def foo(x: int = ... encoding: None = ...) -> str: ... @overload def foo(x: int, encoding: str) -> bytes: ... # for foo(123, "utf-8") @overload def foo(*, encoding: str) -> bytes: ... # for foo(encoding="utf-8") Not only is this hard to read, real examples in typeshed are usually more complex, with many arguments before or after the affected argument or even multiple affected arguments. This often becomes too complex to write or maintain. Here is one example from the wild: https://github.com/python/typeshed/blob/b95b729b9e07ab21d252701af0f5b740467… Allowing non-default arguments after default arguments would solve both use cases above and eliminates a special case. I'm also not sure what exactly the current SyntaxError really protects us from. Adding a non-default after a default argument can't really lead bugs. - Sebastian

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Python multithreading without the GIL
by Sam Gross 31 Jul '23

31 Jul '23

Hi, I've been working on changes to CPython to allow it to run without the global interpreter lock. I'd like to share a working proof-of-concept that can run without the GIL. The proof-of-concept involves substantial changes to CPython internals, but relatively few changes to the C-API. It is compatible with many C extensions: extensions must be rebuilt, but usually require small or no modifications to source code. I've built compatible versions of packages from the scientific Python ecosystem, and they are installable through the bundled "pip". Source code: https://github.com/colesbury/nogil Design overview: https://docs.google.com/document/d/18CXhDb1ygxg-YXNBJNzfzZsDFosB5e6BfnXLlej… My goal with the proof-of-concept is to demonstrate that removing the GIL is feasible and worthwhile, and that the technical ideas of the project could serve as a basis of such an effort. I'd like to start a discussion about these ideas and gauge the community's interest in this approach to removing the GIL. Regards, Sam Gross colesbury(a)gmail.com / sgross(a)fb.com

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Mixed Python/C debugging
by Skip Montanaro 26 Apr '23

26 Apr '23

Having tried comp.lang.python with no response, I turn here... After at least ten years away from Python's run-time interpreter & byte code compiler, I'm getting set to familiarize myself with that again. This will, I think, entail debugging a mixed Python/C environment. I'm an Emacs user and am aware that GDB since 7.0 has support for debugging at the Python code level. Is Emacs+GDB my best bet? Are there any Python IDEs which support C-level breakpoints and debugging? Thanks, Skip

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Call for papers for PyCon 2023
by Amna Ahsan 20 Apr '23

20 Apr '23

Hi, I am writing to you on behalf of PyCon Estonia <https://pycon.ee/> to invite you to take part in the call for papers for our 2023 edition and join us as a speaker at PyCon: https://pyconestonia.typeform.com/to/hBOEtTQ3 This is the fifth of the annual PyCon Estonia event organised by our NGO Python Estonia <https://pythonestonia.ee/> which is dedicated to education and awareness about Python in the region. In previous years <https://www.youtube.com/playlist?list=PLyN-ewDaUNUjVLLL1VPzRyySKPhd807hH>, keynote speakers at PyCon Estonia have included Travis Oliphant, Larry Hastings, Raymond Hettinger and Andrew Godwin. We've had around 200+ participants join us for a live conference in Tallinn. This year we're having a two day conference, with bigger audience. The theme for PyCon Estonia 2023 is "Python in Machine Learning and AI" and we want to talk about the AI and ML projects built with Python and how AI is impacting the tech sector in general. We would really like to have you offer a possible topic for a talk at PyCon. If this would be something you are interested in, please submit a proposal here: https://pyconestonia.typeform.com/to/hBOEtTQ3 before the *09th May, 2023* If you have any questions, please don't hesitate to write to me. Best Regards, *Amna Ahsan* Marketing Partner *Python Estonia* +372 5784 0436

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[RELEASE] Python 3.11.3, 3.10.11 and 3.12.0 alpha 7 released
by Thomas Wouters 05 Apr '23

05 Apr '23

It's time for another set of Python releases! *Python 3.11.3, 3.10.11 and 3.12 alpha 7 are now available*. Python 3.12.0 alpha 7 The final alpha release of Python 3.12! The next release will be beta 1, which is also the feature freeze. Last chance to get your new features and API changes into 3.12! https://www.python.org/downloads/release/python-3120a7/ *246 new commits since 3.12.0a6.* Python 3.11.3 More bugfixes and security fixes for the best Python version (so far). https://www.python.org/downloads/release/python-3113/ *167 new commits since 3.11.2* Python 3.10.11 The final regular bugfix release for Python 3.10! It is now entering security-fix-only mode. This also means this is the last version for which we will ship Windows and macOS installers. If you rely on these binary releases, it's time to upgrade to Python 3.11. https://www.python.org/downloads/release/python-31011/ *121 new commits since 3.10.10.* We hope you enjoy the new releases! Thanks to all of the many volunteers who help make Python Development and these releases possible! Please consider supporting our efforts by volunteering yourself or through organization contributions to the Python Software Foundation. https://www.python.org/psf/ From the release team, Thomas Wouters @thomas Pablo Galindo Salgado @pablogsal Łukasz Langa @ambv Ned Deily @nad Steve Dower @steve.dower

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Small lament...
by Skip Montanaro 03 Apr '23

03 Apr '23

Just wanted to throw this out there... I lament the loss of waking up on April 1st to see a creative April Fool's Day joke on one or both of these lists, often from our FLUFL... Maybe such frivolity still happens, just not in the Python ecosystem? I know you can still import "this" or "antigravity", but those are now old (both introduced before 2010). When was the last time a clever easter egg was introduced or an April Fool's Day joke played? ¯\_(ツ)_/¯ Skip

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