🌐 Mailman 3 January 2025 - Python-list - python.org

Any way to "subclass" typing.Annotated?
by Ian Pilcher Jan. 31, 2025

Jan. 31, 2025

(Note: I have mail delivery disabled for this list and read it through GMane. Please copy me on any responses, so that I can respond with proper threading.) From the things that I probably shouldn't spend my free time on department ... As background, I'm working on a project that is going to involve a bunch of abstract classes and dynamic types, and I've found that Python's existing abstract class implementation leaves a lot to be desired, particularly the inability to create abstract class variables and class methods. Having been seduced by the Siren song of Python's flexibility, I've been rolling my own implementation. Now to my question. I'm currently using annotations to create abstract class variables, for example: class Foo(object, metaclass=AbstractType): acv: Annotated[int, abstract] ('abstract' is simply a unique "flag" object.) This works just fine, but it's somewhat un-idiomatic. What I'd like to be able to do is create my own type, so that I could do something like this: class Foo(object, metaclass=AbstractType): acv: AbstractClassVariable[int] Essentially I'd like to create "subclass" of typing.Annotated that always sets the metadata to 'abstract'. Thus far, I haven't found a way to do this, as typing.Annotated can't be subclassed. Anyone have any ideas? -- ======================================================================== If your user interface is intuitive in retrospect ... it isn't intuitive ========================================================================

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sys.call_tracing
by Rob Cliffe Jan. 31, 2025

Jan. 31, 2025

From the documentation on the sys module at https://docs.python.org/3/library/sys.html: sys.call_tracing(/func/, /args/) Call |func(*args)|, while tracing is enabled. The tracing state is saved, and restored afterwards. This is intended to be called from a debugger from a checkpoint, to recursively debug or profile some other code. Tracing is suspended while calling a tracing function set by |settrace()| <https://docs.python.org/3/library/sys.html#sys.settrace> or |setprofile()| <https://docs.python.org/3/library/sys.html#sys.setprofile> to avoid infinite recursion. |call_tracing()| enables explicit recursion of the tracing function. Is there any reason it doesn't support sys.call_tracing(/func/, /args/, kargs) to call func(*args, **kargs) ? Best wishes Rob Cliffe

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How to properly use py-webrtcvad?
by marc nicole Jan. 22, 2025

Jan. 22, 2025

Hi, I am getting audio from my mic using PyAudio as follows: self.stream = audio.open(format=self.FORMAT, > channels=self.CHANNELS, > rate=self.RATE, > input=True, > frames_per_buffer=self.FRAMES_PER_BUFFER, > input_device_index=1) then reading data as follows: for i in range(0, int(self.RATE / self.FRAMES_PER_BUFFER * > self.RECORD_SECONDS)): > data = self.stream.read(4800) on the other hand I am using py-webrtcvad as follows: self.vad = webrtcvad.Vad() and want to use *is_speech*() using audio data from PyAudio. But getting the error: return _webrtcvad.process(self._vad, sample_rate, buf, length) > Error: Error while processing frame no matter how I changed the input data format (wav: using speech_recognition's *get_wav_data*(), using numpy...) Any suggestions (using Python 2.x)? Thanks.

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Re: bool type have big problem. finally program returned "True".Is this the TRUE spec?
by Alan Bawden Jan. 20, 2025

Jan. 20, 2025

あうぇくろ <deqser25(a)gmail.com> writes: tpr=composite(type,print) print(tpr('a')==tpr(1)) Why does tpr('a')==tpr(1) return True? Because tpr always returns the value None.

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Struggling to understand Callable type hinting
by Ian Pilcher Jan. 18, 2025

Jan. 18, 2025

I am making my first attempt to use type hinting in a new project, and I'm quickly hitting areas that I'm having trouble understanding. One of them is how to write type hints for a method decorator. Here is an example that illustrates my confusion. (Sorry for the length.) import collections.abc class BufferScanner(object): def __init__(self, buf: str) -> None: self._buffer = buf self._index = 0 self._eof = False self._line = 1 self._column = 1 @property def eof(self) -> bool: return self._eof @staticmethod def _check_eof(method: collections.abc.Callable -> ( collections.abc.Callable ): def wrapper(*args, **kwargs): self = args[0] if not self._eof: method(*args, **kwargs) if self._index >= len(self._buffer): self._eof = True return self._eof return wrapper @_check_eof def next_line(self) -> None: """Advance the scanner to the beginning of the next line.""" try: i = self._buffer.index('\n', self._index) except ValueError: self._index = len(self._buffer) # decorator will set _eof return self._index = i + 1 # move past the newline self._line += 1 self._column = 1 I cannot figure out how to correctly specify the Callable argument and return type for _check_eof(). As indicated by the name, method should be a method (of the BufferScanner class), so its first positional argument should always be an instance of BufferScanner, but it could have any combination of positional and/or keyword arguments after that. I've read the TypeVar and ParamSpec documentation, and me head is spinning, but neither one really seems to help with this situation. Any pointers to good resources or the correct way to do this are appreciated. Thanks! -- ======================================================================== If your user interface is intuitive in retrospect ... it isn't intuitive ========================================================================

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bool type have big problem. finally program returned "True".Is this the TRUE spec?
by あうぇくろ Jan. 18, 2025

Jan. 18, 2025

from typing import List from types import FunctionType, LambdaType def composite(*func: List[FunctionType]) -> LambdaType: if len(func) < 2: raise TypeError(f'composite expected over 2 arguments, but got {len(func)}') if len(func) == 2: return lambda *args, **kwargs: func[1](func[0](*args, **kwargs)) return lambda *args, **kwargs: composite(*func[1:])(func[0](*args, **kwargs )) tpr=composite(type,print) print(tpr('a')==tpr(1)) I subscribed to python-list, so I sent this message again. Why does tpr('a')==tpr(1) return True?

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Re: Strategies for avoiding having to use --break-system-packages with pip
by Chris Green Jan. 18, 2025

Jan. 18, 2025

Peter J. Holzer <hjp-python(a)hjp.at> wrote: > [-- text/plain, encoding quoted-printable, charset: us-ascii, 32 lines --] > > On 2025-01-14 11:32:35 +0000, Chris Green via Python-list wrote: > > Use a virtual environment, what do I have to do then to make using > > my program (that uses tkintertable) 'transparent', i.e. I just > > want to be able to run the program from the command prompt like > > any other program. > > Just use the python interpreter in the venv in the hashbang line. > > For example, here's the first line of one my scripts: > > #!/usr/local/share/wds/venv/bin/python3 > > As you can probably guess, the venv is in /usr/local/share/wds/venv. > > There is no need for wrapper scripts which activate the venv. Python > does that all by itself. > > I have a small script, install-python[1], to assist with setting the > hashbang, but if it's just a few scripts you can simply edit it manually. > OP here. Yes, thank you, I thought that the shebang line would do the trick but it's nioce to have it confirmed. -- Chris Green ·

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Re: Tools to help with text mode (i.e. non-GUI) input
by Lele Gaifax Jan. 18, 2025

Jan. 18, 2025

Chris Green via Python-list <python-list(a)python.org> writes: > I'm looking for Python packages that can help with text mode input, > i.e. for use with non-GUI programs that one runs from the command > prompt in a terminal window running a bash shell or some such. I'd suggest giving a try to https://pypi.org/project/questionary/, seems very close to what you are looking for and very simple to drive. Another package is https://github.com/petereon/beaupy, that seems a good fit as well. ciao, lele. -- nickname: Lele Gaifax | Quando vivrò di quello che ho pensato ieri real: Emanuele Gaifas | comincerò ad aver paura di chi mi copia. lele(a)metapensiero.it | -- Fortunato Depero, 1929.

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Strategies for avoiding having to use --break-system-packages with pip
by Chris Green Jan. 17, 2025

Jan. 17, 2025

I have a (relatively) clean Debian 12 installation running on my two workhorse systems, a desktop server at home and my laptop that travels around with me. I moved from Xubuntu to Debian on both these systems a few months ago. I ran Xubuntu for many years and acquired a whole lot of python packages installed with pip, as root. For the last couple of years I had to use the --break-system-packages option to get things installed. As far as I'm aware I never hit any dependency problems doing this. It's probably because things I installed with pip were mostly quite small, specialised, packages that I used in just one or two utility programs that I had written myself. In quite a few cases these were realated to image processing and such things. So far I've managed to keep my Debian 12 installations 'pip free', I haven't even got pip installed. However I may have just come across something that would at least be very useful and it comes from PyPi. (It's tkintertable if that's of any interest or relevance) What are my options? Just install it using pip as root and --break-system-packages, what's likely to break? Use a virtual environment, what do I have to do then to make using my program (that uses tkintertable) 'transparent', i.e. I just want to be able to run the program from the command prompt like any other program. Download tkintertable from git into my development environment and use that. My PYTHONPATH will need to point to it but I can't see any further issues with doing this. Anything else? As far as I can see using pipx doesn't help me at all (see recent thread here). -- Chris Green ·

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Re: Tools to help with text mode (i.e. non-GUI) input
by Keith Thompson Jan. 17, 2025

Jan. 17, 2025

Alan Gauld <learn2program(a)gmail.com> writes: > On 15/01/2025 00:41, Keith Thompson via Python-list wrote: >> Alan Gauld <learn2program(a)gmail.com> writes: >>> On 11/01/2025 14:28, Chris Green via Python-list wrote: >>>> I'm looking for Python packages that can help with text mode input, >>> >>> The standard package for this is curses which comes as part >>> of the standard library on *nix distros. >> >> The thing about curses (which may or may not be a problem) is that, by >> design, it takes over the whole screen. If you want to do simpler text >> manipulations (showing a dismissible message, showing bold text, etc.) >> without interfering with existing text, curses can't do it, at least not >> easily. > > It's not that difficult to use the terminfo codes directly. But > that won't give access to things like lists of default values, mouse > control etc that the OP wanted. But for simple text characteristics > and moving the cursor around terminfo works ok even if a bit tedious. > > Here is "hello world" in bold... > > import curses > curses.setupterm() > bold = curses.tigetstr('bold').decode('ascii') > normal = curses.tigetstr('sgr0').decode('ascii') > > print(bold, 'Hello world', normal) Cool -- but I think you want: print(bold, 'Hello world', normal, sep='') > Whilst you can position the cursor etc it very quickly > becomes easier to just use full blown curses. -- Keith Thompson (The_Other_Keith) Keith.S.Thompson+u(a)gmail.com void Void(void) { Void(); } /* The recursive call of the void */

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