🌐 Mailman 3 September 2023 - Python-list - python.org

Python 3.11.5 Pip Issue
by Jacob Keeler Sept. 14, 2023

Sept. 14, 2023

I downloaded Python 3.11.5, and there was nothing in the “Scripts” file, and there was no Pip. I would like to know why. Thank you, Jacob

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Tkinter ttk Treeview binding responds to past events!
by John O'Hagan Sept. 13, 2023

Sept. 13, 2023

I was surprised that the code below prints 'called' three times. from tkinter import * from tkinter.ttk import * root=Tk() def callback(*e): print('called') tree = Treeview(root) tree.pack() iid = tree.insert('', 0, text='test') tree.selection_set(iid) tree.selection_remove(iid) tree.selection_set(iid) tree.bind('<<TreeviewSelect>>', callback) mainloop() In other words, selection events that occurred _before_ the callback function was bound to the Treeview selections are triggering the function upon binding. AFAIK, no other tk widget/binding combination behaves this way (although I haven't tried all of them). This was a problem because I wanted to reset the contents of the Treeview without triggering a relatively expensive bound function, but found that temporarily unbinding didn't prevent the calls. I've worked around this by using a regular button-click binding for selection instead, but I'm curious if anyone can cast any light on this. Cheers John

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ANN: Wed 20 Sep: Terminal-based user interfaces (TUIs) with ease using Textual
by dn Sept. 7, 2023

Sept. 7, 2023

Rodrigo's back! Fresh from his successes at EuroPython... You are invited to join the next virtual NZPUG Auckland Branch meeting (Wed 20 Sep, 1830~2030 local, ie 0630~0830 UTC) Learn how to build powerful terminal-based user interfaces (TUIs) with ease using Textual - an open-source Python framework. Through this tutorial, you'll learn how to use features like Textual's built-in widgets, reactive attributes, and message-passing system, to start developing a simple TODO app that runs directly in your terminal. About Rodrigo Girão Serrão: Rodrigo has presented to NZPUG Auckland Branch previously. He speaks frequently at various PyCons (Python Conferences) and other gatherings. As well as Python, he has been playing with APL, C++, and more. Combining programming and maths, he describes himself as a mathemagician. Rodrigo has always been fascinated by problem solving and that is why he picked up programming – so that he could solve more problems. He also loves sharing knowledge, and that is why he spends so much time writing articles in his blog, writing on Twitter, and giving workshops and courses. During the week, Rodrigo can be found banging his head against the wall while trying to solve a Textual bug, as he works on Textual full-time. To RSVP (to receive the meeting-URL) and for more detail: https://www.meetup.com/nzpug-auckland/events/295433884/ The Auckland branch of the New Zealand Python Users Group meets twice monthly. You're very welcome to attend online or in-person (as available). Meeting location-details or URL will be sent to those who RSVP. We are a healthy mix of Python users. Students, academics, hobbyists, industry professionals, and many completely new to Python. The 'room' opens at 1815 (local time) with an opportunity to network with colleagues. Formal start is 1830. Aiming to finish by 2030. We are always keen to hear suggestions for meeting-topics, and to meet with folk who'd like to present or lead - eg a brief lightning talk, a practical coaching-session, a full lecture... Help is available if you've never done such a thing before! We follow the NZPUG Code of Conduct to create an inclusive and friendly environment. We express thanks to, and encourage you to investigate our sponsors: Catalyst Cloud, New Zealand Open Source Society, JetBrains, and IceHouse Ventures. -- Regards, =dn

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Python 3.12.0 rc2 (final release candidate) now available.
by Thomas Wouters Sept. 6, 2023

Sept. 6, 2023

I'm pleased to announce the release of Python 3.12 release candidate 2. https://www.python.org/downloads/release/python-3120rc2/ This is the second release candidate of Python 3.12.0 This release, *3.12.0rc2*, is the last release preview for Python 3.12. There will be *no ABI changes* from this point forward in the 3.12 series. The intent is for the final release of 3.12.0, scheduled for Monday, 2023-10-02, to be identical to this release candidate. *This is the last chance to find critical problems in Python 3.12.* <https://discuss.python.org/t/python-3-12-0rc2-final-release-candidate-relea…>Call to action We strongly encourage maintainers of third-party Python projects to prepare their projects for 3.12 compatibilities during this phase, and where necessary publish Python 3.12 wheels on PyPI to be ready for the final release of 3.12.0. Any binary wheels built against Python 3.12.0rc2 will work with future versions of Python 3.12. As always, report any issues to the Python bug tracker <https://github.com/python/cpython/issues>. Please keep in mind that this is a preview release and while it’s as close to the final release as we can get it, its use is *not* recommended for production environments. <https://discuss.python.org/t/python-3-12-0rc2-final-release-candidate-relea…>Core developers: time to work on documentation now - Are all your changes properly documented? - Are they mentioned in What’s New <https://docs.python.org/3.12/whatsnew/3.12.html>? - Did you notice other changes you know of to have insufficient documentation? <https://discuss.python.org/t/python-3-12-0rc2-final-release-candidate-relea…>Major new features of the 3.12 series, compared to 3.11 <https://discuss.python.org/t/python-3-12-0rc2-final-release-candidate-relea…>New features - More flexible f-string parsing <https://docs.python.org/3.12/whatsnew/3.12.html#pep-701-syntactic-formaliza…>, allowing many things previously disallowed (PEP 701 <https://peps.python.org/pep-0701/>). - Support for the buffer protocol <https://docs.python.org/3.12/whatsnew/3.12.html#pep-688-making-the-buffer-p…> in Python code (PEP 688 <https://peps.python.org/pep-0688/>). - A new debugging/profiling API <https://docs.python.org/3.12/whatsnew/3.12.html#pep-669-low-impact-monitori…> (PEP 669 <https://peps.python.org/pep-0669/>). - Support for isolated subinterpreters <https://docs.python.org/3.12/whatsnew/3.12.html#pep-684-a-per-interpreter-g…> with separate Global Interpreter Locks (PEP 684 <https://peps.python.org/pep-0684>). - Even more improved error messages <https://docs.python.org/3.12/whatsnew/3.12.html#improved-error-messages>. More exceptions potentially caused by typos now make suggestions to the user. - Support for the Linux perf profiler <https://docs.python.org/3.12/howto/perf_profiling.html> to report Python function names in traces. - Many large and small performance improvements <https://docs.python.org/3.12/whatsnew/3.12.html#optimizations> (like PEP 709 <https://peps.python.org/pep-0709/>), delivering an estimated 5% overall performance improvementcitation needed. <https://discuss.python.org/t/python-3-12-0rc2-final-release-candidate-relea…>Type annotations - New type annotation syntax <https://docs.python.org/3.12/whatsnew/3.12.html#pep-695-type-parameter-synt…> for generic classes (PEP 695 <https://peps.python.org/pep-0695/>). - New override decorator <https://docs.python.org/3.12/whatsnew/3.12.html#pep-698-override-decorator-…> for methods (PEP 698 <https://peps.python.org/pep-0698>). <https://discuss.python.org/t/python-3-12-0rc2-final-release-candidate-relea…> Deprecations - The deprecated wstr and wstr_length members of the C implementation of unicode objects were removed, per PEP 623 <https://peps.python.org/pep-0623/>. - 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 <https://peps.python.org/pep-0594/> and PEP 632 <https://peps.python.org/pep-0632/>. The setuptools package continues to provide the distutils module. - A number of other old, broken and deprecated functions, classes and methods <https://docs.python.org/3.12/whatsnew/3.12.html#removed> 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.) (Hey, *fellow core developer,* if a feature you find important is missing from this list, let Thomas know <thomas(a)python.org>.) For more details on the changes to Python 3.12, see What’s new in Python 3.12 <https://docs.python.org/dev/whatsnew/3.12.html>. The next scheduled release of Python 3.12 will be 3.12.0, the *final release*, currently scheduled for 2023-10-02. <https://discuss.python.org/t/python-3-12-0rc2-final-release-candidate-relea…>More resources - Online Documentation <https://docs.python.org/3.12/>. - PEP 693 <https://www.python.org/dev/peps/pep-0693/>, the Python 3.12 Release Schedule. - Report bugs via GitHub Issues <https://github.com/python/cpython/issues>. - Help fund Python and its community <https://www.python.org/psf/donations/>. <https://discuss.python.org/t/python-3-12-0rc2-final-release-candidate-relea…>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-landing/>. Your release team, Thomas Wouters Ned Deily Steve Dower Łukasz Langa -- Thomas Wouters <thomas(a)python.org>

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Passing info to function used in re.sub
by Jan Erik Moström Sept. 5, 2023

Sept. 5, 2023

I'm looking for some advice for how to write this in a clean way I want to replace some text using a regex-pattern, but before creating replacement text I need to some file checking/copying etc. My code right now look something like this: def fix_stuff(m): # Do various things that involves for info # that what's available in m replacement_text = m.group(1) + global_var1 + global_var2 return replacement_text and the call comes here global_var1 = "bla bla" global_var2 = "pff" new_text = re.sub(im_pattern,fix_stuff,md_text) The "problem" is that I've currently written some code that works but it uses global variables ... and I don't like global variables. I assume there is a better way to write this, but how? = jem

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Displaying CPU instruction sets used for TensorFlow build?
by Loris Bennett Sept. 5, 2023

Sept. 5, 2023

Hi, Does anyone know how I can display the CPU instruction sets which were used when TensorFlow was compiled? I initially compiled TF on a machine with a CPU which supports AVX512_VNNI. I subsequently recompiled on a second machine without AVX512_VNNI, but when I run a test program on the second machine, I get the error: The TensorFlow library was compiled to use AVX512_VNNI instructions, but these aren't available on your machine. I would like to check the instruction sets explicitly, so I can tell whether I am using the version of TF I think I am, or whether the test program has some sort of problem. Cheers, Loris -- This signature is currently under constuction.

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Finding good documentation for gpiod
by Chris Green Sept. 4, 2023

Sept. 4, 2023

I am using the gpiod package for manipulating GPIO inputs/outputs on a Beaglebone Black SBC (like a Raspberry Pi but with more flexible I/O). Mostly I am managing to get things to work as I want but better documentation of gpiod would be a great help. For example, when one has found an I/O pin (a 'line' in GPIO parlance) that one wants to use one has to 'request' it using the Line.request() method. The help for this is as follows:- Help on method_descriptor: request(...) request(consumer[, type[, flags[, default_val]]]) -> None Request this GPIO line. consumer Name of the consumer. type Type of the request. flags Other configuration flags. default_val Default value of this line. Note: default_vals argument (sequence of default values passed down to LineBulk.request()) is still supported for backward compatibility but is now deprecated when requesting single lines. Which is pretty good **except** that I can't find a proper description of the parameters anywhere, i.e. there's nowhere that even tells me what types of values/objects the parameters are. At the end of the gpiod.Line section of the help there is this:- | ACTIVE_HIGH = 1 | | ACTIVE_LOW = 2 | | BIAS_AS_IS = 1 | | BIAS_DISABLE = 2 | | BIAS_PULL_DOWN = 4 | | BIAS_PULL_UP = 3 | | DIRECTION_INPUT = 1 | | DIRECTION_OUTPUT = 2 Which **might** be appropriate values for 'type' or 'flags' but there doesn't seem to be any way of knowing. Am I missing something very obvious somewhere? Is there a 'standard' way of finding out parameter information? It may well be that I'm simply banging up against the limit of what documentation is available, I have managed to get code working OK. It's just that I'd be happier if I really know what I was doing! :-) -- Chris Green ·

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Forward References
by Jonathan Gossage Sept. 3, 2023

Sept. 3, 2023

I am attempting to use forward references in my program and I am failing. This also does not work with the older way of putting the name of a class as a string. Here is some sample code: from __future__ import annotations from dataclasses import dataclass from typing import TypeAlias ColorDef: TypeAlias = RGB | int | str @dataclass(frozen=True, slots=True) class RGB(object): Can anyone suggest how I should fix this without reversing the statement order? pass -- Jonathan Gossage

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iterations destroy reversed() results
by Pierre Fortin Sept. 3, 2023

Sept. 3, 2023

Hi, reversed() results are fine until iterated over, after which the results are no longer available. This was discovered after using something like this: rev = reversed( sorted( list ) ) sr = sum( 1 for _ in rev ) # rev is now destroyed So reversed() results can only be iterated once unlike sorted(), etc... Script to illustrate the issue: /tmp/rev: orig = [ 'x', 'a', 'y', 'b', 'z', 'c' ] co = sum( 1 for _ in orig ) print( 'orig', orig, co ) # reversing rev = reversed(orig) print( 'before iteration:', [ x for x in rev ] ) # list comprehension was an iteration over 'rev' print( 'after iteration:', [ x for x in rev ] ) # how this was discovered... orig = [ 'x', 'a', 'y', 'b', 'z', 'c' ] rev = reversed(orig) cr = sum( 1 for _ in rev ) print( 'after sum():', [ x for x in rev ] ) which produces: $ python /tmp/rev orig ['x', 'a', 'y', 'b', 'z', 'c'] 6 before iteration: ['c', 'z', 'b', 'y', 'a', 'x'] after iteration: [] after sum(): [] Regards, Pierre

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Re: Why do I always get an exception raised in this __init__()?
by Chris Green Sept. 1, 2023

Sept. 1, 2023

Alan Gauld <learn2program(a)gmail.com> wrote: > On 31/08/2023 22:15, Chris Green via Python-list wrote: > > > class Gpiopin: > > > > def __init__(self, pin): > > # > > # > > # scan through the GPIO chips to find the line/pin we want > > # > > for c in ['gpiochip0', 'gpiochip1', 'gpiochip2', 'gpiochip3']: > > > > chip = gpiod.Chip(c) > > for l in range(32): > > line = chip.get_line(l) > > if pin in line.name(): > > print("Found: ", line.name()) > > return > > else: > > raise ValueError("Can't find pin '" + pin + "'") > > You don't store the line anywhere. > You need to use self.line > self.line = chip.get_line(l) > if pin... > > > def print_name(self): > > print (self.line.name()) > > > > def set(self): > > self.line.set_value(1) > > > > def clear(self): > > self.line.set_value(0) > > As you do here. > Yes, OK, absolutely. However that wasn't my original rather basic problem which was, as I said, that I wasn't running the code I was looking at. The above was just a quick hack from some even cruder code doing the same job, trying to develop it into something better and more general. It's all on a headless Beaglebone Black (bit like a Raspberry Pi) so I'm doing everything via multiple ssh connections and sometimes this results in "the left hand not knowing what the right hand is doing"! -- Chris Green ·

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