#internals-and-peps | Python | Page 48

deft gyro Jun 14, 2020, 1:04 PM

#

what

peak spoke Jun 14, 2020, 1:08 PM

#

Usually easier to just subclass UserList etc. with design and behaviour

spark magnet Jun 14, 2020, 1:12 PM

#

@lost nexus the problem with subclassing builtins like that is it is easy to slip back to a real list: l = MyList(); l = l[:3] # oops, l is list, not MyList

lost nexus Jun 14, 2020, 1:22 PM

#

I see

unkempt rock Jun 14, 2020, 1:30 PM

#

hey

#

📎 YRvk0.png

#

I'm getting this error

#

when running headless chrome via python script

grave jolt Jun 14, 2020, 1:50 PM

#

Please read the channel description @unkempt rock

#

This is a discussion channel, not a help channel

#

Hm, maybe it's possible to make a member deriver.

unkempt rock Jun 14, 2020, 1:53 PM

#

member driver

#

the script is working good via chrome non -headless mode

grave jolt Jun 14, 2020, 1:53 PM

#

Oh, I'm talking about the inheriting list problem

#

If you want help with a specific question, check out #❓｜how-to-get-help. This is not a help channel

unkempt rock Jun 14, 2020, 1:54 PM

#

okay,

#

askin on #help-carrot

primal magnet Jun 14, 2020, 1:56 PM

#

Event: ???

grave jolt Jun 14, 2020, 1:57 PM

#

@derive
class MyList1(list):
    # slices return  MyList instances
    pass 

@derive
class MyList2(list):
    # slices return  MyList instances
    # `update`, `__add__` and `__iadd__` are redefined to use the new `append`
    
    def __init__(self, iterable):
        self.container = list(iterable)

    def __setitem__(self, index, item):
        self.container[index] = item

    def append(self, x):
        self.container.append(x)

primal magnet Jun 14, 2020, 1:58 PM

#

H m m

true ridge Jun 14, 2020, 2:11 PM

#

UserList is slightly more useful then subclassing since it always wraps the result to the subclass (via self.__class__)

grave jolt Jun 14, 2020, 2:16 PM

#

Will it work correctly if I implement, say, an immutable linked list?

gloomy rain Jun 14, 2020, 2:46 PM

#

How come dict.keys() returns KeysView[Optional[key_type]] rather than KeyView[key_type]?

#

Or, at least, mypy seems to think so.

#

Oh, nevermind, it was just the type inference acting up.

cloud crypt Jun 14, 2020, 2:51 PM

#

ah

peak spoke Jun 14, 2020, 2:51 PM

#

Typeshed has KeysView[_KT]

cloud crypt Jun 14, 2020, 2:51 PM

#

^

#

or at least it should

#

mypy is pretty dumb at times ngl

gloomy rain Jun 14, 2020, 2:52 PM

#

Yeah, it wasn't an issue with the return type, it was mypy inferring an optional type on the result of a dict comprehension.

cloud crypt Jun 14, 2020, 2:52 PM

#

def whatever(
    ...
) -> return_type:
    ...``` _no return type of the func_

gloomy rain Jun 14, 2020, 2:52 PM

#

In my code.

cloud crypt Jun 14, 2020, 2:52 PM

#

and I don’t want to fix my code just by # type: ignoring all its mistakes

gloomy rain Jun 14, 2020, 2:55 PM

#

Sometimes, although in this case it was actually correct and it was my fault.

cloud crypt Jun 14, 2020, 2:56 PM

#

indeed, but I have shown an example that makes me wonder above

#

ever tried to make a function that takes str and bytes and calls their methods? that’s helly

#

well unless you use typing overload

merry pollen Jun 14, 2020, 3:04 PM

#

honesty i have p good experience with mypy 90% of the time

cloud crypt Jun 14, 2020, 3:17 PM

#

I mean

#

mypy just gives up if you do some magic like _ctypes.PyCFuncPtr

unkempt rock Jun 14, 2020, 4:25 PM

#

How do i make an os with python?

visual hatch Jun 14, 2020, 4:25 PM

#

What are functions Annotations?

I recently been trying to learn a little bit of functional programing in python and I came across the word annotations. After searching and watching few videos I still didn't get a clear view of what are the function annotations and why they could be useful in python. I'll be very thankful if you guys answere the following questions in a simple way to let me get a better understanding of it.

What are functions annotations used for?
What will it effect on my functions parameters if I used them in function?
Does they effect in any manner at my function?

I'll be really happy if you guys could explain these to me or maybe share some youtube videos which help me understand these.

Thank you so much.

visual shadow Jun 14, 2020, 4:29 PM

#

They are the groundwork on which type hints are born. A way to add additional info about parameters and return values

unkempt rock Jun 14, 2020, 4:29 PM

#

Can anyone suggest me a good python machine learning tutorial?

cloud crypt Jun 14, 2020, 4:30 PM

#

nope, as annotations are optional

unkempt rock Jun 14, 2020, 4:30 PM

#

See on udemy

visual shadow Jun 14, 2020, 4:30 PM

#

Which means, the big thing is this: function annotations do nothing for the code execution. They're mostly there for the humans who are reading the code

cloud crypt Jun 14, 2020, 4:30 PM

#

even though there are static type checkers like mypy, which is their de-facto

visual shadow Jun 14, 2020, 4:30 PM

#

Once that part clicks, the rest is easy to understand

cloud crypt Jun 14, 2020, 4:31 PM

#

you can hook your function to dynamically check inputs based on annotations, but that's just ew

#

you can have use of annotations like discord.py does, though

visual shadow Jun 14, 2020, 4:31 PM

#

So 2. And 3. Are nope in native python. You can have libraries or programs built on top of it that tries to turn them into something more, as nekit mentioned

#

But keep them aside when you first try to comprehend function annotations themselves.

peak spoke Jun 14, 2020, 4:34 PM

#

Their only effect is that they're added to the __annotations__ attribute

cloud crypt Jun 14, 2020, 4:35 PM

#

also annotations can be used in order to create something like a dataclass

#

yeah

#

I once wrote some thing for ctypes with it ```python
from ctypes import wintypes
import ctypes

kernel32 = ctypes.WinDLL("kernel32")

@func_def(kernel32.CreateToolhelp32Snapshot)
def create_snapshot(flags: wintypes.DWORD, process_id: wintypes.DWORD) -> wintypes.HANDLE:
pass```

#

which sets the argument/return types for DLL function in order to make calling it simpler

#

~ Finally read about descriptors in python, haha ~

raven pike Jun 14, 2020, 4:49 PM

#

yesterday i checked out function scopes and global etc

#

i'm mainly using pandas, and when i change outer df in my functions it actually changes

#

shouldnt it be changed at all in the end?

#

im confused

cloud crypt Jun 14, 2020, 4:51 PM

#

can you show an example?

visual hatch Jun 14, 2020, 5:26 PM

#

I got it now so basically they are the hints for human. To better understand what types of value function will take and what it will return.

#

I was thinking its somekind of way to make functions take only a specific types of values but I was wrong as that is not the case

charred wagon Jun 14, 2020, 5:30 PM

#

They are used by mypy, which is a tool that statically checks that the types are correct

#

But it doesn't enforce anything at runtime

raven pike Jun 14, 2020, 5:31 PM

#

@cloud crypt i'll post now, one min

#

df = pd.DataFrame([0,1,2,3])
0
0    0
1    1
2    2
3    3

def example(df):
    df.iloc[0] = 99
    return None

example(df)

df
0
0    99
1    1
2    2
3    3

#

@cloud crypt

cloud crypt Jun 14, 2020, 5:47 PM

#

what's confusing in it

#

ah

#

well

#

DataFrame is mutable

#

and you mutate the object

#

this has nothing to do with scopes really

#

lemon = [1, 2, 3]

def append_n(some_list, n):
    some_list.append(n)

append_n(lemon, 4)

print(lemon)  # [1, 2, 3, 4]```

raven pike Jun 14, 2020, 5:48 PM

#

so scope is just for variables?

#

protected that way

#

so... global keyword is just for variables in order for them to be manipulated?

flat gazelle Jun 14, 2020, 5:50 PM

#

Yes. Variables are names of objects and are affected by scope. Objects themselves are not

raven pike Jun 14, 2020, 5:51 PM

#

hmmm, good to know. i was always worried if my pandas object would be changed or not when entering a function

#

if i dont want them to be changed, then using .copy() would be a good practice for me

#

when passing in funcs

#

thanks @cloud crypt @flat gazelle

tacit hawk Jun 14, 2020, 6:19 PM

#

well functions that change the object's state could be owned by the object

unkempt rock Jun 14, 2020, 6:22 PM

#

you guys are talking magic

tacit hawk Jun 14, 2020, 6:22 PM

#

to be a safe copy, you would need to do a deep copy. I think that is costly

unkempt rock Jun 14, 2020, 6:24 PM

#

is pycharm a good text editor for python beginners?

tacit hawk Jun 14, 2020, 6:25 PM

#

pycharm is an IDE, it comes with a bunch of features

#

I use visual studio code

raven pike Jun 14, 2020, 6:52 PM

#

@tacit hawk yeah deep copy but some computational stuff needs to be done in a big dataframe, so i have to use copy of a section to do various stuff

#

some of them might change the original, that's what i'm afraid of

proper narwhal Jun 14, 2020, 7:12 PM

#

@tacit hawk ide is like a tool kit and one of the tools is a python compiler??????

tacit hawk Jun 14, 2020, 7:16 PM

#

Idk if pycharm installer comes with python or you need to install it. But yes, IDE is a collection of tools that helps you, it is not just a text editor

craggy bane Jun 14, 2020, 7:19 PM

#

If I recall, pycharm comes by itself. You install Python, then you tell Pycharm where it is.

#

I apologize if the above information is inaccurate. I don't use Pycharm anymore. I now use NotePad++ then use Powershell to compile and view the output.

near coral Jun 14, 2020, 7:26 PM

#

props to you for using Powershell

#

wish I could tolerate it

craggy bane Jun 14, 2020, 7:28 PM

#

It took a bit of setup and I had to learn some Powershell syntax. It was a bit of a pain initially, but after I used it for awhile, I don't think I wanna go back to an IDE except for debugging or other resources.

crisp wharf Jun 14, 2020, 7:30 PM

#

Hello, im a student trying to learn python by myself. I have worked with Flask, Docker, REST API + Postman, MongoDB, PostgreSQL , automatic tests and doing DJANGO project now. Are there any other popular libraries/ solutions worth learning?

craggy bane Jun 14, 2020, 7:32 PM

#

Props to you. You've gotten your feet wet in more things than I have. As for things "worth learning", I just go with what interests me. I'm not too familiar with the trends of the industry, even though I probably should be.

crisp wharf Jun 14, 2020, 7:35 PM

#

Thanks, could you give some examples? Might be interesting for me too

hollow crane Jun 14, 2020, 7:36 PM

#

do lots of little projects that interest you

#

new apis and maybe some new ways of thinking you'll have to encounter

raven pike Jun 14, 2020, 9:39 PM

#

Check stack overflow surveys

#

Then go after what's popular if that's what you are after for

unkempt rock Jun 14, 2020, 10:25 PM

#

Hello, im a student trying to learn python by myself. I have worked with Flask, Docker, REST API + Postman, MongoDB, PostgreSQL , automatic tests and doing DJANGO project now. Are there any other popular libraries/ solutions worth learning?
@crisp wharf By automatic testing do you mean pytest and unittest?

north root Jun 14, 2020, 10:27 PM

#

@crisp wharf have you deployed to production before?

#

this is off-topic for this channel, however

magic python Jun 14, 2020, 11:09 PM

#

@tacit hawk you can't copy matplotlib axis objects - not sure if you're aware of why that is?

i tried recently with deep copy, and it failed, so you saying that above reminded me

tacit hawk Jun 14, 2020, 11:10 PM

#

No I am not aware, I don't know that lib

night patrol Jun 14, 2020, 11:24 PM

#

I've an idea

#

I want to build an fps counter

#

Do you guys have any idea on the best way to capture the frames of the display?

#

What I'm thinking is to capture 1 pixel from the screen using opencv, is it efficient idk, maybe?

alpine cedar Jun 14, 2020, 11:33 PM

#

What I'm thinking is to capture 1 pixel from the screen using opencv, is it efficient idk, maybe?
@night patrol maybe more than one

#

what if the pixels stay the same

grave jolt Jun 14, 2020, 11:34 PM

#

@night patrol This is not the right channel for this (read the channel description). Check out #❓｜how-to-get-help

night patrol Jun 14, 2020, 11:40 PM

#

oh sorry

#

@alpine cedar #help-coconut

merry pollen Jun 15, 2020, 1:14 AM

#

uh hmn. so, back before delayed type annotations, you could pass in functions as type annotations

#

but now they're strings & the suggested method to get objects back from annotations is eval, which doesn't seem to be cooperating easily with functions

#

so my question is, is there a convenient means of embedding functions into delayed annotations

#

and/or get a function back via eval()

#

oh hmn okay jk apparently annotations take care of all of that if you pass in the annotation as a string

#

...weird

#

i guess pycharm just hasnt gotten the linting down for that yet

raven ridge Jun 15, 2020, 1:29 AM

#

https://www.python.org/dev/peps/pep-0563/#non-typing-usage-of-annotations

uses for annotations incompatible with the aforementioned PEPs should be considered deprecated.

With the aforementioned PEPs referring to using annotations to provide type hints. By my reading, using annotations for purposes other than type hinting is deprecated.

Python.org

PEP 563 -- Postponed Evaluation of Annotations

The official home of the Python Programming Language

paper echo Jun 15, 2020, 2:15 AM

#

im not sure what "incompatible with PEP 484" would mean

#

presumably some of the experimental libraries that use type hints for runtime validation

merry pollen Jun 15, 2020, 2:35 AM

#

@raven ridge is what one would think, but pep 593

#

so 3 years ago maybe

#

but given pep 593's acceptance, runtime annotations are back on the menu

lost nexus Jun 15, 2020, 4:45 AM

#

is there a max amount of references that an object can have?

north root Jun 15, 2020, 4:45 AM

#

probably until you run out of memory

raven ridge Jun 15, 2020, 4:48 AM

#

https://github.com/python/cpython/blob/e9684fac5a158be9806304a676e619857520a4dc/Include/object.h#L107 - on a 64-bit build of CPython, a Py_ssize_t maxes out at 2**63 - 1. So, one object maxes out at 9,223,372,036,854,775,807 references.

lost nexus Jun 15, 2020, 4:56 AM

#

haha alright

prime estuary Jun 15, 2020, 5:59 AM

#

Which is also the maximum amount of addressable memory, so you'll hit the OS ram limit before being able to have that many objects to reference it from.

raven ridge Jun 15, 2020, 6:04 AM

#

Technically it's one byte less than half the maximum amount of addressable memory, and technically it's possible to add a reference without using any additional memory.

#

It's possible to reach that max reference count without running out of memory first, though very very unlikely. Absent a bug, it would require externalizing pointers out of the process with the intention of reading them back in later for the decref call, or something like that.

#

But I wouldn't be shocked to learn that Python doesn't guard against that, since you have to really be doing something weird (or forgetting decref calls, meaning you have a bug) in order to get that to happen

raven ridge Jun 15, 2020, 7:04 AM

#

Indeed, CPython doesn't bother to guard for overflow. https://github.com/python/cpython/blob/e9684fac5a158be9806304a676e619857520a4dc/Include/object.h#L427

GitHub

python/cpython

The Python programming language. Contribute to python/cpython development by creating an account on GitHub.

undone hare Jun 15, 2020, 7:29 AM

#

!pep 611

fallen slateBOT Jun 15, 2020, 7:29 AM

#

**PEP 611 - The one million limit**

Link

Status

Draft

Created

05-Dec-2019

Type

Standards Track

undone hare Jun 15, 2020, 7:29 AM

#

This PEP is about adding a one million safe limit to most things in the interpreter

wide shuttle Jun 15, 2020, 8:15 AM

#

I've been looking into https://www.python.org/dev/peps/pep-0518/ recently (pyproject.toml) and came across a blogpost by Brett Cannon about the subject. There's nothing really groundbreaking in the post, but it's nicely written and provided a coherent story on the why and what: https://snarky.ca/what-the-heck-is-pyproject-toml/

Python.org

PEP 518 -- Specifying Minimum Build System Requirements for Python ...

The official home of the Python Programming Language

Tall, Snarky Canadian

What the heck is pyproject.toml?

Recently on Twitter there was a maintainer of a Python project who had a couple of bugs filed against their project due to builds failing (this particular project doesn't provide wheels, only sdists). Eventually it came out that the project was using a pyproject.toml file beca...

wide shuttle Jun 15, 2020, 10:53 AM

#

Hey, @magic junco, this is not a help channel, but rather a discussion channel to discuss Python itself, from higher-level perspective. We do have help channels and you can claim one for your question (see #❓｜how-to-get-help). Sorting algorithms also sounds like something that could fit in the #algos-and-data-structs topical channel.

magic junco Jun 15, 2020, 10:53 AM

#

oh, sorry about that

cedar nimbus Jun 15, 2020, 10:56 AM

#

can we get switch-case with python 4?

undone hare Jun 15, 2020, 10:57 AM

#

!pep 3103

fallen slateBOT Jun 15, 2020, 10:57 AM

#

**PEP 3103 - A Switch/Case Statement**

Link

Status

Rejected

Python-Version

3.0

Created

25-Jun-2006

Type

Standards Track

molten onyx Jun 15, 2020, 10:57 AM

#

Guido is adding it in actually

undone hare Jun 15, 2020, 10:57 AM

#

Status : Rejected
Probs- wait what

molten onyx Jun 15, 2020, 10:57 AM

#

also there won't be 4.0 afterall

#

they got a new parser

#

sec

undone hare Jun 15, 2020, 10:58 AM

#

Ah that's true

molten onyx Jun 15, 2020, 10:58 AM

#

he said so explicitly in a talk I forgot which

#

and also

undone hare Jun 15, 2020, 10:58 AM

#

I wonder why LL(1) can't parse it, the proposal seems to be parsable

molten onyx Jun 15, 2020, 10:59 AM

#

https://github.com/python/cpython/commit/b45af1a5691e83b86321fc52d173f66cf891ce5f
https://youtu.be/QppWTvh7_sI?t=2510

YouTube

North Bay Python

"Writing a PEG parser for fun and profit" - Guido van Rossum (North...

Parsing Expression Grammars (PEGs) are a relatively new formalism for describing grammars suitable for automatically generating efficient parsers. I've become interested in using a PEG-generated parser as an alternative to CPython's nearly 30 year old "pgen" parser generator. ...

▶ Play video

flat gazelle Jun 15, 2020, 11:00 AM

#

match statement may be more powerful than switch case

molten onyx Jun 15, 2020, 11:06 AM

#

yes

#

definitely

cloud crypt Jun 15, 2020, 11:08 AM

#

match is cooler yeah

cedar nimbus Jun 15, 2020, 11:08 AM

#

idk really since i didnt even know anything about it

flat gazelle Jun 15, 2020, 11:09 AM

#

match [1, 2, 3]:
    case [1, 2, a]: print(a)
    case [*b]: print(b[1])
``` maybe

#

or maybe a less powerful form

#

full pattern matching seems a bit unneeded

cloud crypt Jun 15, 2020, 11:09 AM

#

typo in match

flat gazelle Jun 15, 2020, 11:09 AM

#

ty

cloud crypt Jun 15, 2020, 11:09 AM

#

soft keywords sounds neat

#

multi line lambdas when lemon_pleased

unkempt rock Jun 15, 2020, 11:11 AM

#

is there any way to create my own low level programming language?

#

thanks in advance guys

cloud crypt Jun 15, 2020, 11:12 AM

#

not quite related to this channel?

cedar nimbus Jun 15, 2020, 11:12 AM

#

you can make functions in python

#

and classess

unkempt rock Jun 15, 2020, 11:12 AM

#

i dont have any idea of this topic

cloud crypt Jun 15, 2020, 11:12 AM

#

also what do you define as low level programming language

unkempt rock Jun 15, 2020, 11:12 AM

#

not high as python

#

where should i ask it ?

cloud crypt Jun 15, 2020, 11:13 AM

#

well not as high as python is pretty much most of the languages

unkempt rock Jun 15, 2020, 11:13 AM

#

but then certain languages like ruby,r etc?

#

also html!?

cloud crypt Jun 15, 2020, 11:14 AM

#

whatever

unkempt rock Jun 15, 2020, 11:14 AM

#

is there any way to?

molten onyx Jun 15, 2020, 11:14 AM

#

@unkempt rock I'd look into this https://craftinginterpreters.com/

cloud crypt Jun 15, 2020, 11:14 AM

#

question is why, and you wouldn't want to use python for that unless it is a toy language or something

unkempt rock Jun 15, 2020, 11:15 AM

#

nono

#

i am good with python

#

just now completed my machine learning course

flat gazelle Jun 15, 2020, 11:15 AM

#

Most boring, useful languages are written in C.

unkempt rock Jun 15, 2020, 11:15 AM

#

and looking forward

#

i just want to experiment on something different rather than taking my personal projects in python

flat gazelle Jun 15, 2020, 11:18 AM

#

honestly, high level languages are easier, because you can avoid LLVM/ASM and just interpret. Compiling things is not too easy, though you can compile to scheme to save effort (idris 2)

unkempt rock Jun 15, 2020, 11:18 AM

#

oh so you mean that making high level language is easier and efficient ?

flat gazelle Jun 15, 2020, 11:19 AM

#

not sure about efficient

unkempt rock Jun 15, 2020, 11:19 AM

#

ohh then whats the way?

flat gazelle Jun 15, 2020, 11:20 AM

#

depends on what you mean about efficient

unkempt rock Jun 15, 2020, 11:20 AM

#

efficient in sense like python's maplotlib and seaborn libraries

#

it only takes a couple lines

hollow crane Jun 15, 2020, 11:20 AM

#

Efficient to write normally trumps efficient to run

unkempt rock Jun 15, 2020, 11:20 AM

#

but the output is big

hollow crane Jun 15, 2020, 11:21 AM

#

But length of code isn't really efficiency

#

Are you talking about shortness of code or execution speed

unkempt rock Jun 15, 2020, 11:21 AM

#

yeah kind of

hollow crane Jun 15, 2020, 11:21 AM

#

What

#

Which one

#

This isn't even inclusive or

#

It's vaguely affirmative or

unkempt rock Jun 15, 2020, 11:22 AM

#

shortness of code

hollow crane Jun 15, 2020, 11:22 AM

#

That's not a great thing to optimise

flat gazelle Jun 15, 2020, 11:22 AM

#

do you want to write a lang in few lines, or a lang that needs little code to do things

hollow crane Jun 15, 2020, 11:22 AM

#

By all means avoid unnecessarily writing stuff people have written before

unkempt rock Jun 15, 2020, 11:22 AM

#

a lang with little code

hollow crane Jun 15, 2020, 11:22 AM

#

But trying to reduce character count is pointless and normally harmful

unkempt rock Jun 15, 2020, 11:23 AM

#

ohh

flat gazelle Jun 15, 2020, 11:23 AM

#

yeah, do not do that

unkempt rock Jun 15, 2020, 11:23 AM

#

then what about making a lang like c?

wide shuttle Jun 15, 2020, 11:23 AM

#

I think we've strayed a bit from the topic of this channel.

hollow crane Jun 15, 2020, 11:24 AM

#

Yep

unkempt rock Jun 15, 2020, 11:24 AM

#

then is there any other channel for this particular topic?

hollow crane Jun 15, 2020, 11:24 AM

#

#ot2-never-nester’s-nightmare

unkempt rock Jun 15, 2020, 11:25 AM

#

ok thanks for the help i will post there

leaden lava Jun 15, 2020, 12:29 PM

#

Hello fellow Pythonists! I just wanted to ask whether it'd be a good idea to create a tunnel between one of dedicated channels and Stackoverflow Python chat?

#

Here it is https://chat.stackoverflow.com/rooms/6/python

stable grail Jun 15, 2020, 12:31 PM

#

as a pythondiscord server idea?

crisp wharf Jun 15, 2020, 12:31 PM

#

@crisp wharf have you deployed to production before?
@north root didnt get notification, what do you mean?

stable grail Jun 15, 2020, 12:31 PM

#

or as your own personal project?

crisp wharf Jun 15, 2020, 12:32 PM

#

@crisp wharf By automatic testing do you mean pytest and unittest?
@unkempt rock Pytest and mocking for now

leaden lava Jun 15, 2020, 12:33 PM

#

@stable grail As a pythondiscordserver idea

stable grail Jun 15, 2020, 12:34 PM

#

so im personally not sure how we could moderate such a feature. but any pythondiscord ideas can be brought up in the channel for it, its called #community-meta

#

its a channel made for these kind of discussions

leaden lava Jun 15, 2020, 12:38 PM

#

Thanks @stable grail I didn't know that

#

I'll ask it there

urban hollow Jun 15, 2020, 2:30 PM

#

Hi. I wanna make a project with using google maps or normal maps. when i click to any country i wanna get some info about that country from the data base. basicly i will click to africa contenent and program will show what is the pop currency and more

red solar Jun 15, 2020, 2:32 PM

#

what part of that requires google maps?

#

you can just draw a map with python3, have a clickable area on each country, and if you click it, it will show you the info stored in your db?

urban hollow Jun 15, 2020, 2:33 PM

#

which lib i can use for this

red solar Jun 15, 2020, 2:34 PM

#

https://docs.python.org/3/faq/gui.html

#

any of these

#

(for the display part - you need something for your database too - probably start with sqlite3? (or json if you don't want to learn sql)

#

    def acquire(self, blocking=True, timeout=-1):
        me = get_ident()
        if self._owner == me:
            self._count += 1
            return 1
        rc = self._block.acquire(blocking, timeout)
        if rc:
            self._owner = me
            self._count = 1
        return rc

    __enter__ = acquire

#

i had no idea you could do this

wide shuttle Jun 15, 2020, 2:45 PM

#

Could do what?

red solar Jun 15, 2020, 2:48 PM

#

the __enter__ thing

wide shuttle Jun 15, 2020, 3:02 PM

#

Think about it from another perspective, would you be surprised if you saw this at the module level?

#

def function():
    return "some return"


some_name = function

hazy anchor Jun 15, 2020, 3:03 PM

#

i think 'sickened but curious' is the correct reaction.

wide shuttle Jun 15, 2020, 3:04 PM

#

Yeah, it's mainly to bridge towards that this works the same within the context of a class definition

#

It's only that the eventual names end up as class attributes instead of module-level names

#

A def statement still does the same thing: it creates a function object, then assignes a name to that function object so we can use it

#

The only difference is that when that happens within the context of a class definition, assignments end up as class attributes

#

name = [1, 2, 3]

def function():
    pass

class Foo:
    name = [1, 2, 3]

    def function():
        pass

flat gazelle Jun 15, 2020, 3:06 PM

#

what is quite interesting

In [14]: class O:
    ...:     def __int__(self): return 4
    ...:     as_int = int
    ...:

In [15]: O().as_int()
Out[15]: 0

In [16]: class O:
    ...:     def __int__(self): return 4
    ...:     as_int = lambda self: int(self)
    ...:

In [17]: O().as_int()
Out[17]: 4

In [18]: l = lambda s: int(s)

In [19]: class O:
    ...:     def __int__(self): return 4
    ...:     as_int = l
    ...:

In [20]: O().as_int()
Out[20]: 4

wide shuttle Jun 15, 2020, 3:07 PM

#

It's because int does not have a __get__

#

So, in your first example, you don't get a "bound method"

#

You just run int() straight without arguments

#

With gives you a 0

#

It's not the definition that does anything special for "methods"; it's accessing them

#

The descriptor protocol ensures that the object gets passed as the first argument by binding it to the callable

#

That's what "creates" the bound method from the function object

#

As int does not have a __get__ method, no such binding happens and the object does not get "bound" to int

#

You just get int back directly when you access the attribute

#

In the other two cases, you bind the class attribute to a callable that does have a __get__

flat gazelle Jun 15, 2020, 3:11 PM

#

interesting

wide shuttle Jun 15, 2020, 3:11 PM

#

!e

def perfectly_usuable_as_method(self):
    print(self)


class Foo:
    method = perfectly_usuable_as_method

f = Foo()
f.method()

fallen slateBOT Jun 15, 2020, 3:11 PM

#

@wide shuttle :white_check_mark: Your eval job has completed with return code 0.

<__main__.Foo object at 0x7f11e40af9d0>

wide shuttle Jun 15, 2020, 3:11 PM

#

It's not about the place of definition of the callable

#

A def statement (and a lambda expression) just creates a function object and assigns a name to that function object

#

Whenever you assign a name in a class definition, that name just happens to be a class attribute

#

So, there's nothing special at definition time (edit: removed something from this message that had nothing to do with this to avoid confusion)

#

The binding of the object happens at attribute access time

#

It's just that a def statement "hides" the fact that these two statements are very similar:

name = "something"

def name():
    pass

#

Both create an object, and then assign a name to it

#

In R, a function definition is less appealing from a readability perspective, but does make this assignment more clear:

#

name <- function() {
    print("hello!")
}

#

Where you see <- just think = (which is also valid in R, but makes the style zealots of R scream)

#

You can even get bound methods from a function without ever assing a class attribute to a function

#

!e

def my_pseudo_method(self):
    print(self)

print("Function object:", my_pseudo_method)
bound_method = my_pseudo_method.__get__("Hello, world", str)
print("Bound method:", bound_method)
bound_method()

fallen slateBOT Jun 15, 2020, 3:24 PM

#

@wide shuttle :white_check_mark: Your eval job has completed with return code 0.

001 | Function object: <function my_pseudo_method at 0x7f0244559dc0>
002 | Bound method: <bound method my_pseudo_method of 'Hello, world'>
003 | Hello, world

wide shuttle Jun 15, 2020, 3:25 PM

#

(and obviously self is just the conventional name)

magic python Jun 15, 2020, 3:28 PM

#

what's the stacktrace with respect to python debugging?

red solar Jun 15, 2020, 3:29 PM

#

wow i started a whole discussion and missed all of it :/

wide shuttle Jun 15, 2020, 3:29 PM

#

It was mostly me talking to myself

inland acorn Jun 15, 2020, 4:20 PM

#

how I would do this is to make the decorator store the function in a list

#

so I recommend making it as part of a class

#

function_object.__name__

hasty thistle Jun 15, 2020, 4:21 PM

#

can I ask what you're trying to achieve @unkempt rock?

inland acorn Jun 15, 2020, 4:21 PM

#

and also this channel is for discussion about python itself, for help read #❓｜how-to-get-help

hasty thistle Jun 15, 2020, 4:22 PM

#

ah, neat

#

good luck 👌

red solar Jun 15, 2020, 6:08 PM

#

while func(): continue or while func(): pass?

peak spoke Jun 15, 2020, 6:27 PM

#

neither?

red solar Jun 15, 2020, 6:34 PM

#

why not?

peak spoke Jun 15, 2020, 6:39 PM

#

because it'll eat up your cpu

red solar Jun 15, 2020, 6:39 PM

#

oh yeah but apart from that?

spark magnet Jun 15, 2020, 6:41 PM

#

"pass", but what's your real func() do?

red solar Jun 15, 2020, 7:01 PM

#

idk it turned hypothetical

#

originally was for a coroutine, but realised i should put asyncio.sleep(n) there instead

final whale Jun 15, 2020, 7:45 PM

#

How is argument passing handled in py, does it make a new copy everytime?

wide shuttle Jun 15, 2020, 7:46 PM

#

No, the opposite. The names get assigned directly to the arguments that are being passed

#

There's actually a great video about it on YouTube

#

https://www.youtube.com/watch?v=_AEJHKGk9ns

YouTube

PyCon 2015

Ned Batchelder - Facts and Myths about Python names and values - Py...

"Speaker: Ned Batchelder

The behavior of names and values in Python can be confusing. Like many parts of Python, it has an underlying simplicity that can be hard to discern, especially if you are used to other programming languages. Here I'll explain how it all works, and pre...

▶ Play video

#

This explains the basic idea behind how names and values work in Python

#

It also goes it into what happens when you pass arguments to a function

final whale Jun 15, 2020, 7:49 PM

#

time to watch, thank you ! 👍

bright forge Jun 15, 2020, 7:54 PM

#

Is there a way to get the opposite of a slice in python? I have a list of dictionaries and I'm trying to find out how to find what the [int] would be for a specific one.

tacit hawk Jun 15, 2020, 7:56 PM

#

The docs https://docs.python.org/3.7/library/time.html?highlight=time monotonic#time.monotonic of time.monotonic says only the difference between consecutive calls are valid, that means

start = time.monotonic()
time.monotonic()
end = time.monotonic() - start # invalid difference

?

wide shuttle Jun 15, 2020, 8:05 PM

#

No, it means that there's no absolute reference point, so the size of the numbers you get by themselves doesn't really mean anything

#

but the difference between the numbers does. In this case, the calls are all consecutive to each other (following each other in a continuous manner)

unkempt rock Jun 15, 2020, 9:12 PM

#

im trying to learn how to work with sqlite, what should i try to make? like a mini project i mean

red solar Jun 15, 2020, 9:13 PM

#

try making an atomic queue with it 🙂

unkempt rock Jun 15, 2020, 9:13 PM

#

what is that

red solar Jun 15, 2020, 9:13 PM

#

(don't actually use it for this in practice tho)

#

do you know what a queue is?

unkempt rock Jun 15, 2020, 9:13 PM

#

can someone helps me? i am trying to do a welcome/auto-role commands, but them are the same here:

📎 unknown.png

red solar Jun 15, 2020, 9:13 PM

#

#discord-bots

unkempt rock Jun 15, 2020, 9:13 PM

#

like wait in queue to get in a match

red solar Jun 15, 2020, 9:14 PM

#

yeah - so you have pop and push, push pushes an item onto the end of the queue, pop removes an item from the front of the queue

unkempt rock Jun 15, 2020, 9:14 PM

#

what is this about

hollow crane Jun 15, 2020, 9:14 PM

#

not a queue like in overwatch or something

#

well conceptually in that it's a list of things

#

but not specifically that

red solar Jun 15, 2020, 9:14 PM

#

any kinda of queue lmao

#

idk how ow one works

hollow crane Jun 15, 2020, 9:14 PM

#

oh i see i thought you were explaining the concept of a queue in multithreading

#

ignore me

unkempt rock Jun 15, 2020, 9:15 PM

#

i dont know what are we talking about anymore

red solar Jun 15, 2020, 9:15 PM

#

it's a list, you can only add on the end, and remove from the front

#

we call it a queue

unkempt rock Jun 15, 2020, 9:15 PM

#

i just want to do someone with sqlite

hollow crane Jun 15, 2020, 9:15 PM

#

i want to do someone too bud

#

what projects have you done before

red solar Jun 15, 2020, 9:15 PM

#

lmao

unkempt rock Jun 15, 2020, 9:15 PM

#

something* haha

#

ive done tons of things

#

i just wanna do like anything with sqlite to understand it a bit better and then replace my json database with sqlite for my discord bot

red solar Jun 15, 2020, 9:16 PM

#

i still think an atomic queue in sqlite was a good idea 😒

#

why don't u use the project of converting your json database to sqlite to understand it better?

unkempt rock Jun 15, 2020, 9:18 PM

#

u mean go right to my main goal

red solar Jun 15, 2020, 9:18 PM

#

yeah might as well

#

you can always ask people to look at it, and help you along the way

unkempt rock Jun 15, 2020, 9:18 PM

#

but i really dont know that much

#

tbh i know barely anything about it

#

📎 unknown.png

#

help pls

#

bruh

#

#discord-bots

#

and the error is clear

#

ur redefining what u already have defined

red solar Jun 15, 2020, 9:19 PM

#

best way of learning is pushing yourself, and having someone help you 🤷

unkempt rock Jun 15, 2020, 9:20 PM

#

i still kinda wanna do some mini project before

#

nothing too special

dreamy ledge Jun 15, 2020, 9:20 PM

#

Bande de fdp

unkempt rock Jun 15, 2020, 9:20 PM

#

and how i can do to have the welcome message and the auto-roles in the same .py file?

#

just like for example taking the input, storing it inside the database and then retrieving it and printing it out

radiant fulcrum Jun 15, 2020, 9:21 PM

#

@unkempt rock #❓｜how-to-get-help We also have a dedicated #discord-bots for discord.py questsions

magic python Jun 15, 2020, 10:02 PM

#

the following:

@attr.dataclass(frozen=True)
class blah:
    x: float
    y: float
x = blah(1, 2)
type(x)

returns __main__.blah, I'm wondering what would be the most typical way to document this in a doc string

hollow crane Jun 15, 2020, 10:04 PM

#

document the class?

#

i don't really understand i'm afraid

magic python Jun 15, 2020, 10:05 PM

#

i have a function that takes this as input

hollow crane Jun 15, 2020, 10:05 PM

#

takes a blah?

magic python Jun 15, 2020, 10:05 PM

#

yes

hollow crane Jun 15, 2020, 10:05 PM

#

you can typehint with a custom class

#

there's a nice standard way of doing docstrings for argument types

#

📎 unknown.png

magic python Jun 15, 2020, 10:06 PM

#

what's the standard way, I'm not using mypy or anything

hollow crane Jun 15, 2020, 10:06 PM

#

this is how pycharm likes it and it's fairly common

#

you can still use typehints to document the code

magic python Jun 15, 2020, 10:06 PM

#

looks kinda rst ish, i tend to use similar structure

#

but I don't know what i'd write, if i have

def foo(x, y, blah_obj):
   '''
   Args:
       blah_obj( __main__.blah): blah obj with x, y values
   '''

just this i guess 🤔

hollow crane Jun 15, 2020, 10:07 PM

#

yeah that should be fine i think

magic python Jun 15, 2020, 10:08 PM

#

__main__ looked weird to me for some reason

hollow crane Jun 15, 2020, 10:08 PM

#

eh just say blah

#

__main__.blah is just trying to give a nice way of describing where it is

#

like if your package is called fooblifier

#

i'd say the argument type should be given as fooblifier.Blah

#

or just Blah

magic python Jun 15, 2020, 10:09 PM

#

i've never used the package like that before

#

perhaps it's similar to pd.DataFrame though

hollow crane Jun 15, 2020, 10:09 PM

#

sorry?

magic python Jun 15, 2020, 10:10 PM

#

putting the package name in the docstring for namespacing like that

pliant tusk Jun 15, 2020, 10:13 PM

#

kinda makes me wish that fstrings worked as docstrings

#

def foo(x, y, blah_obj):
   f'''
   Args:
       blah_obj( {__name__}.blah): blah obj with x, y values
   '''```
*this doesnt work cause of how docstrings are handled internally*

#

cause then that would work

tepid dune Jun 15, 2020, 10:14 PM

#

who has python advanced tutorial!

#

?

spice pecan Jun 15, 2020, 10:16 PM

#

Something along the lines of

class Sample:
    __doc__ = f'''
    haha yes hello I'm a doc string
    '''
``` should work, but that's for classes, functions will just be a pain

pliant tusk Jun 15, 2020, 10:16 PM

#

yea that would work for classes

magic python Jun 15, 2020, 10:17 PM

#

i think matplotlib has a bunch of autogenerated stuff 🤔

spice pecan Jun 15, 2020, 10:17 PM

#

def func(): pass
func.__doc__ = f'''My doc f-string''' # ew```

magic python Jun 15, 2020, 10:17 PM

#

this? idk what that decorator does

📎 unknown.png

pliant tusk Jun 15, 2020, 10:18 PM

#

that prob copys the docstring from Figure.text and sets it on figtext if i had to guess

spice pecan Jun 15, 2020, 10:18 PM

#

Looks like it copies the docstring from Figure.text and puts it as the function's docstring

#

# Allegedly similar to this
def copy_doc(source):
    def actual_decorator(func):
        func.__doc__ = source.__doc__
        return func
    return actualy_decorator```

magic python Jun 15, 2020, 10:20 PM

#

is this common? Or a mpl thing

#

mpl seems like it's a bit of a mess, i tried to copy an axis object the other week and got no where

spice pecan Jun 15, 2020, 10:21 PM

#

I haven't encountered docstring.copy personally, but it sounds like something that would be common

#

I could see it being a part of functools

paper echo Jun 15, 2020, 10:35 PM

#

is there a good reason why __copy__ and __deepcopy__ are missing from https://docs.python.org/3/reference/datamodel.html#special-method-names ? is this a documentation bug?

#

@pliant tusk they cant work as docstrings because then you'd have to execute the function to get the docstring, which would be a huge mess

pliant tusk Jun 15, 2020, 10:37 PM

#

i mean, that makes sense

peak spoke Jun 15, 2020, 10:44 PM

#

@paper echo It's not really something that's defined on a lot of objects and relies on a module (excluding the copy methods on mutable sequences etc), they are documented under https://docs.python.org/3/library/copy.html although it's not in the regular method -> description format

magic python Jun 15, 2020, 10:45 PM

#

@peak spoke do you know why one wouldn't be able to copy an object? I tried to copy a matplotlib.axis object and it didn't work, and i don't really understand why

#

seems that it should just be some thing in memory? Why is copying some things ok but not others 🤔

peak spoke Jun 15, 2020, 10:47 PM

#

I don't know about the axis, but it can have data that is not copyable (doesn't make sense in an another object), depend on external connections like callbacks etc. or the behaviour is just not defined for it as it didn't seem necessary

magic python Jun 15, 2020, 10:48 PM

#

i wanted to copy so that i could have functions that worked as typical functions, instead of loads of global state

#

but yeah, no idea

paper echo Jun 15, 2020, 10:51 PM

#

@peak spoke yeah but "this is rare" isn't a good reason to omit a special method name from the special method name docs page

peak spoke Jun 15, 2020, 10:55 PM

#

All of those methods can be accessed directly through basic python syntax or are used somewhere along the way to emulate types etc. while the interaface of the copy methods is the copy module

spark magnet Jun 15, 2020, 10:56 PM

#

@magic python btw, don't use that ":param:" style of docstring. it's gross, and there's a better standard format.

magic python Jun 15, 2020, 10:57 PM

#

@spark magnet 😄 I don't use that

#

"""
Args
   foo (int): thing
   bar (float): something else
"""

is what i go for

peak spoke Jun 15, 2020, 10:57 PM

#

There are a few more dunders that are used by modules like that, like pickling

final whale Jun 15, 2020, 11:16 PM

#

Is python handling elif and else: if: differently ?

hollow crane Jun 15, 2020, 11:18 PM

#

nope, behaviour should be exactly the same, however i have no idea about execution speed

#

if you're just asking about basic behaviour

peak spoke Jun 15, 2020, 11:20 PM

#

They both get parsed to the same instruction I believe

spark magnet Jun 15, 2020, 11:20 PM

#

@final whale they are the same

final whale Jun 15, 2020, 11:23 PM

#

thought that py would parse them differently

#

thank you Seagull, Numerlor and Nedbat 👍

red solar Jun 16, 2020, 1:53 AM

#

could you always access class attributes through self?

raven ridge Jun 16, 2020, 1:56 AM

#

I'm not aware of any version where you couldn't.

red solar Jun 16, 2020, 2:08 AM

#

i swear pycharm always used to get mad at me for it

rich wharf Jun 16, 2020, 4:13 AM

#

i'd like to make an infodecorator class for people to use and me to use

#

should I try something like this

#

@InfoDecorator
class myDecorator:
  x: List[int]
  y: Optional[int]

for decorator creation

#

or more like a namedtuple

#

myDecorator = infoDecorator('myDecorator', 'x y', defaults = {'y': None})```

#

to be used like this

#

def somefunc():
  pass

print(somefunc in myDecorator) #False

@myDecorator([1, 2, 3])
def otherfunc():
  pass

print(otherfunc in myDecorator) #True
print(otherfunc.x) #[1, 2, 3]
print(otherfunc.y) #None

grave jolt Jun 16, 2020, 5:11 AM

#

And why is it a decorator?

rich wharf Jun 16, 2020, 5:15 AM

#

@grave jolt I figured that would be the best way to add information to functions

#

I can decorate it with the decorator and I'll still have a callable object but with extra useful properties

grave jolt Jun 16, 2020, 5:17 AM

#

Well, that's very similar to a shortcut to a class creation

#

Maybe make myDecorator a class factory

#

And then check membership with isinstance, as with namedtuple

red solar Jun 16, 2020, 6:29 AM

#

do submissions take a while to appear on the python mailing list? i sent an email to a list i'm subbed to, and can't see it in the archives or under my posted, and haven't received a response/confirmation :/

wide shuttle Jun 16, 2020, 6:31 AM

#

Which list did you send something to?

red solar Jun 16, 2020, 6:32 AM

#

python-ideas

wide shuttle Jun 16, 2020, 6:33 AM

#

as far as I know, that list isn't moderated up front other than that you need to be a subscriber

#

but I'm not exactly sure

red solar Jun 16, 2020, 6:35 AM

#

Hmmm... can u check if you can see my question?

wide shuttle Jun 16, 2020, 6:35 AM

#

I don't know what you sent

red solar Jun 16, 2020, 6:36 AM

#

It has my name on it tho (eventfd stuff is what I sent)

rich wharf Jun 16, 2020, 6:37 AM

#

One of the things I really wish Python had was better anonymous functions

#

But they will probably never be added

#

There are a number of reasons for this but I would quite like the feature

#

Although I know it won't be added

#

Lambdas are unreadable and not powerful for a lot of Python tasks currently

wide shuttle Jun 16, 2020, 6:39 AM

#

I think you showed me a use case for more powerful lambdas before

#

but, I haven't really seen the use of them in practice

rich wharf Jun 16, 2020, 6:39 AM

#

yeah, but it's a rare one

wide shuttle Jun 16, 2020, 6:40 AM

#

I'd very much prefer regular def statements for functions

rich wharf Jun 16, 2020, 6:40 AM

#

I'd refer using them for event handling

wide shuttle Jun 16, 2020, 6:40 AM

#

And I fear overuse and unreadable code, almost to the point of javascript

red solar Jun 16, 2020, 6:40 AM

#

Considering you can define functions inside functions, are lambdas really needed for anything other than conciseness?

jolly flax Jun 16, 2020, 6:40 AM

#

Isn't Lisp more oriented for Lambda expressions? (I'm not that versed, just that i knew somebody who was really into it and tried teaching me a bit)

rich wharf Jun 16, 2020, 6:40 AM

#

handle.event(2, message => (
  if True:
    print(3)
))

wide shuttle Jun 16, 2020, 6:40 AM

#

Which I think is the prime example of allowing for unreadable anonymous function chains

flat gazelle Jun 16, 2020, 6:40 AM

#

they are nice for event handlers and that is pretty much it

rich wharf Jun 16, 2020, 6:41 AM

#

And in cases where you want to group them inside objects

flat gazelle Jun 16, 2020, 6:41 AM

#

and you can do that with decorators

rich wharf Jun 16, 2020, 6:41 AM

#

If I wanted to make a class with a callback, anonymous functions are a good way to go

flat gazelle Jun 16, 2020, 6:41 AM

#

python really does not like callbacks

rich wharf Jun 16, 2020, 6:41 AM

#

I prefer anonymous callbacks

brave badger Jun 16, 2020, 6:41 AM

#

iirc lambdas can't be used when scheduling callbacks for Kivy

rich wharf Jun 16, 2020, 6:42 AM

#

I wish they would be added to Python but they won't be

red solar Jun 16, 2020, 6:42 AM

#

Can lambdas store local variables? (Be a closure or whatever)

rich wharf Jun 16, 2020, 6:42 AM

#

Not yet

#

Well actually yes, @red solar

flat gazelle Jun 16, 2020, 6:42 AM

#

sort of

rich wharf Jun 16, 2020, 6:42 AM

#

lambda: (
  x := 1,
  print(x)
)

#

so, yes @red solar

#

but they don't work with nonlocal or global or etc

#

and this is getting #esoteric-python

red solar Jun 16, 2020, 6:43 AM

#

What’s nonlocal? Thread local?

flat gazelle Jun 16, 2020, 6:43 AM

#

a = 8
b = lambda: a
c = lambda a=a:a
a = 9
print(b(), c()) # 9 8

#

you could also use def here

rich wharf Jun 16, 2020, 6:44 AM

#

@flat gazelle that's the expected usage for functions too

#

def functions

flat gazelle Jun 16, 2020, 6:44 AM

#

the question was about lambdas

#

though def works the same

rich wharf Jun 16, 2020, 6:44 AM

#

Can lambdas store local variables? (Be a closure or whatever)

#

this was the question

#

it wasn't about defaults and variable getting

#

But anyways, lambda power would be a useful change to me

flat gazelle Jun 16, 2020, 6:46 AM

#

this is what a closure is though...

red solar Jun 16, 2020, 6:46 AM

#

feels kinda cheating, storing the variable as a default param

rich wharf Jun 16, 2020, 6:46 AM

#

That's true

#

@red solar There's a better and more clear way

#

lambda: (
  x := 1
)

#

But lambdas that do this aren't pythonic

flat gazelle Jun 16, 2020, 6:47 AM

#

that does something entirely different

rich wharf Jun 16, 2020, 6:47 AM

#

It still stores a local variable though, right?

wide shuttle Jun 16, 2020, 6:47 AM

#

What’s nonlocal? Thread local?
@red solar

No, nonlocal is for names in the nearest enclosing scope that is not the global scope. You usually see it in things like decorators where you define a function within a function:

def outer():
    counter = 0
    def inner():
        nonlocal counter
        counter += 1

red solar Jun 16, 2020, 6:47 AM

#

oh nice

#

but also why? just don't define it locally before you use it

flat gazelle Jun 16, 2020, 6:48 AM

#

but he was asking about closures, and := is not really useful for closures

rich wharf Jun 16, 2020, 6:48 AM

#

I don't interpret it that way

#

I'm interpreting Can lambdas store local variables? (Be a closure or whatever) as Can lambdas store local variables? (Through closures or some other method)

red solar Jun 16, 2020, 6:49 AM

#

sorry i asked that badly, i meant through clojures but my mind had a brain freeze and i wasn't sure if clojure was the right term

flat gazelle Jun 16, 2020, 6:49 AM

#

clojure is not, closure is

red solar Jun 16, 2020, 6:50 AM

#

*closure lol

flat gazelle Jun 16, 2020, 6:51 AM

#

there is no neater way that I know of to capture the value of an outer variable

#

Lisp and raku do that by default, but python resolves names when the function gets called

raven ridge Jun 16, 2020, 7:03 AM

#

but also why? just don't define it locally before you use it
@red solar nonlocal let's you rebind a variable in an enclosing scope to a new value. Without nonlocal you can read or modify an object from an enclosing scope, but not assign to it.

wide shuttle Jun 16, 2020, 7:07 AM

#

@red solar Take a look at this very naive decorator:

#

!e

def count_calls(func):
    counter = 0

    def wrapper(*args, **kwargs):
        nonlocal counter
        counter += 1
        print(f"This function has been called {counter} times")
        return func(*args, **kwargs)

    return wrapper


@count_calls
def foo():
    print("Running foo!")


@count_calls
def bar():
    print("running bar!")


foo()
foo()
foo()
bar()
bar()
foo()

fallen slateBOT Jun 16, 2020, 7:07 AM

#

@wide shuttle :white_check_mark: Your eval job has completed with return code 0.

001 | This function has been called 1 times
002 | Running foo!
003 | This function has been called 2 times
004 | Running foo!
005 | This function has been called 3 times
006 | Running foo!
007 | This function has been called 1 times
008 | running bar!
009 | This function has been called 2 times
010 | running bar!
011 | This function has been called 4 times
... (truncated - too many lines)

Full output: https://paste.pythondiscord.com/ikomuwiwuy

wide shuttle Jun 16, 2020, 7:08 AM

#

We don't want to redefine counter each time the wrapper/function is called, since we need to keep a count across calls

red solar Jun 16, 2020, 7:12 AM

#

ahh ok i see - kinda seems like static local

#

but ok that use makes sense

#

Completely forgot variable name shadowing was a thing in python

hollow crane Jun 16, 2020, 8:57 AM

#

Why doesn't counter get garbage collected there

#

What's the reasoning behind there still being a reference to it

#

Is that just how decorators work

wide shuttle Jun 16, 2020, 8:59 AM

#

The inner function holds a reference to the nonlocal object in its closure

#

Otherwise, decorators couldn't work at all (if you think about it, the function that was passed in, func, also is nonlocal to the inner function)

hollow crane Jun 16, 2020, 9:00 AM

#

Ahhh I see what I'm not understanding

#

Ok thanks

wide shuttle Jun 16, 2020, 9:03 AM

#

!e

def outer(func):
    def inner():
        print(func)
    print(inner.__closure__)

@outer
def some_function():
    pass

fallen slateBOT Jun 16, 2020, 9:03 AM

#

@wide shuttle :white_check_mark: Your eval job has completed with return code 0.

(<cell at 0x7f5b551749d0: function object at 0x7f5b55120e50>,)

shut anchor Jun 16, 2020, 9:38 AM

#

I mostly use it in sorted calls.

#

Whenever you don't feel like doing a def

brave badger Jun 16, 2020, 9:39 AM

#

Typically in one-off function calls that take a key parameter

radiant fulcrum Jun 16, 2020, 9:39 AM

#

i'd say in any place where you are not going to use the function more and once

#

like pure says a one off

gloomy rain Jun 16, 2020, 9:40 AM

#

@unkempt rock A lambda is unnamed, which implies it will only be used in one place. It can also only contain a single expression, so it should be relatively simple.

radiant fulcrum Jun 16, 2020, 9:40 AM

#

its generally bad practice to assign lambda to a var and use it multiple times

gloomy rain Jun 16, 2020, 9:40 AM

#

Well, it's pointless, for one thing.

#

You could just declare a regular function then.

modern night Jun 16, 2020, 9:41 AM

#

and lamda syntax isn't great, functions are much more readable

radiant fulcrum Jun 16, 2020, 9:41 AM

#

its good for one offs

gloomy rain Jun 16, 2020, 9:41 AM

#

There are certain functions that take another function as a parameter, in order to customize its behavior.

radiant fulcrum Jun 16, 2020, 9:41 AM

#

where a dedicated function is probably not worth it

#

but things like this:

📎 unknown.png

gloomy rain Jun 16, 2020, 9:42 AM

#

If you need to call such a function, but you don't want to declare a proper function for the parameter, you can use a lambda.

flat gazelle Jun 16, 2020, 9:42 AM

#

sorted(some_list, key=lambda x: int(x.id))

radiant fulcrum Jun 16, 2020, 9:42 AM

#

ps: stolen from #esoteric-python

gloomy rain Jun 16, 2020, 9:42 AM

#

sorted is an example of such a case

#

It's a function that sorts something, and you can customize its behavior by supplying a function to define what property it should sort by.

glad goblet Jun 16, 2020, 9:43 AM

#

anyone uses vscode?

gloomy rain Jun 16, 2020, 9:43 AM

#

You can declare a proper function to do that, like so: ```py
def my_sort_order(x):
return int(x.id)

sorted(some_list, key=my_sort_order)

glad goblet Jun 16, 2020, 9:43 AM

#

im in this weird situation

gloomy rain Jun 16, 2020, 9:43 AM

#

But that's pretty verbose.

#

@glad goblet If this is a help question, please see #❓｜how-to-get-help

#

This channel is for discussion, not help.

glad goblet Jun 16, 2020, 9:44 AM

#

oh ok

gloomy rain Jun 16, 2020, 9:45 AM

#

@unkempt rock The version @flat gazelle showed is less cumbersome to write, if you're not planning to reuse my_sort_order elsewhere.

flat gazelle Jun 16, 2020, 9:46 AM

#

that is pretty much it. You can also give them more parameters for formatting purposes

gloomy rain Jun 16, 2020, 9:47 AM

#

There are lots of situations where you want to embed values inside strings, and there are a bunch of different ways to do it.

flat gazelle Jun 16, 2020, 9:48 AM

#

f"{user_name:20}"``` will always be at least 20 characters, padding with spaces. You can make the stuff after `:` more complex to choose a specific char for padding, choose the padding side, limit size of the string, set the precision for float, ...

gloomy rain Jun 16, 2020, 9:48 AM

#

v1 = "Hello, " + name + ", how are you?"  # Cumbersome
v2 = "Hello, %s, how are you?" % name  # Better, but hard to know what %s refers to in context
v3 = f"Hello, {name}, how are you?"  # Best of both worlds

flat gazelle Jun 16, 2020, 9:50 AM

#

other things you can use are

f"{str(20)!r}" == "'20'" #use repr instead of str for getting the string to embed
f'{20 + 30 = }' == '20 + 30 = 50'#include the contents within {}, then place the result

#

| is the or operator, it is set union and bitwise or as well

#

or is logical/boolean or

#

| is bitwise or

#

{1, 2} | {3, 4} == {1, 2, 3, 4}
0b1010 | 0b1100 == 0b1110
{1: 2} | {2: 3} == {1: 2, 2: 3} # 3.9 only

#

you can customize the behavior with the __or__ method

magic python Jun 16, 2020, 11:59 AM

#

how does one ensure that the parameters in the docstring reflect those of the function arguments? Is this just visually? Or is there a better / more robust approach

paper echo Jun 16, 2020, 12:08 PM

#

pycharm yells at me if they get out of sync 😛

#

it would be nice if sphinx also yelled at you for it

#

im not sure if theres a standalone docstring linting tool that checks for such a thing. maybe one could be built using sphinx APIs

peak spoke Jun 16, 2020, 12:17 PM

#

Hopefully there aren't that many that it becomes impossible to keep track of in the docstring, but I usually only document the ones that need more beyond their name and a typehint

gloomy rain Jun 16, 2020, 12:20 PM

#

@magic python This is kind of an inherent problem with relying on comments. It's hard to ensure they stay up to date, because unlike code, they aren't validated just by running the code.

#

I realize docstrings are hard to avoid. I think Pycharm inspections is probably the only tool I'm aware of.

paper echo Jun 16, 2020, 12:22 PM

#

https://docs.pylint.org/en/1.6.0/extensions.html @magic python pylint supports this

night coral Jun 16, 2020, 3:22 PM

#

can we specify which type of variable do we want in a lambda? is it possible? like in defs

def somemethod(somestr: str, someint: int):
```?

peak spoke Jun 16, 2020, 3:25 PM

#

Yes, you can typehint any name

wide shuttle Jun 16, 2020, 3:27 PM

#

The lambda syntax does not allow annotations, as far as I know

#

as the : is already in use as the separator between the argument list and the expression

#

If you assign the lambda to a name, you could probably annotate that name, but then you're assigning a lambda to a name

#

and not really annotation the lambda object internally

#

Lambda
lambda's syntax does not support annotations. The syntax of lambda could be changed to support annotations, by requiring parentheses around the parameter list. However it was decided [12] not to make this change because:

It would be an incompatible change.

Lambdas are neutered anyway.

The lambda can always be changed to a function.
https://www.python.org/dev/peps/pep-3107/#lambda

Python.org

PEP 3107 -- Function Annotations

The official home of the Python Programming Language

crystal pebble Jun 16, 2020, 3:32 PM

#

Neutered?

hasty thistle Jun 16, 2020, 3:35 PM

#

they probably mean that you can do more with a function compared to a lambda

#

multiple statements etc

wide shuttle Jun 16, 2020, 3:36 PM

#

They are neutered in the way that they don't carry a lot of debugging information

#

When you define a function, the function object keeps track of things like the initial name it was assigned to

#

A lambda does not do things like that

crystal pebble Jun 16, 2020, 3:38 PM

#

Ah

unkempt rock Jun 16, 2020, 4:12 PM

#


c = ssock.getpeercert(True)
x509 = M2Crypto.X509.load_cert_der_string(c)
publickey = x509.get_pubkey()
key = Crypto.PublicKey.RSA.importKey(publickey.as_der())

modulus = key.n
public_exponent = key.e``` How to get the modulus of certificate in Python 3?

#

The above code works for Python 2

gloomy rain Jun 16, 2020, 4:15 PM

#

@unkempt rock This is not a help channel. If you need help, see #❓｜how-to-get-help .

unkempt rock Jun 16, 2020, 4:15 PM

#

Okay

#

I thought of this as advanced python question

gloomy rain Jun 16, 2020, 4:16 PM

#

That's not what the topic says.

#

Discussion on the use cases, implementation and future of the Python programming language including PEPs, advanced language concepts, new releases, the standard library, and the overall design of the language.

unkempt rock Jun 16, 2020, 4:16 PM

#

Hmmm

#

Could you please answer this issue in help-silicon?

gloomy rain Jun 16, 2020, 4:17 PM

#

No, and don't advertise your help channel in other channels.

unkempt rock Jun 16, 2020, 4:18 PM

#

Okay

rich wharf Jun 16, 2020, 5:31 PM

#

I think we could add lambda annotations

#

lambda (x = 5: int), (y = 4: str): 5 * (x + y)

flat gazelle Jun 16, 2020, 5:33 PM

#

but why?

full jay Jun 16, 2020, 5:33 PM

#

Also it'd be flipped

#

(x: int = 5) for example

flat gazelle Jun 16, 2020, 5:33 PM

#

you already know the type the lambda has, because you are passing to something that has a type hint

boreal umbra Jun 16, 2020, 5:38 PM

#

If you implement your own version of the function type, how do you make functions with it?

#

A decorator?

flat gazelle Jun 16, 2020, 5:39 PM

#

sounds reasonable

hollow crane Jun 16, 2020, 5:39 PM

#

why would you ever want annotations for a lambda

boreal umbra Jun 16, 2020, 5:39 PM

#

@hollow crane t y p i n g

hollow crane Jun 16, 2020, 5:39 PM

#

but like

#

you don't type annotate every line of code

#

a lambda isn't really a function

wide shuttle Jun 16, 2020, 5:40 PM

#

I think we could add lambda annotations
@rich wharf

It was discussed (parentheses around the entire parameter list), but ultimately rejected

flat gazelle Jun 16, 2020, 5:40 PM

#

actually, is there a function that works like an identity function for functions?

brave badger Jun 16, 2020, 5:40 PM

#

I'd argue that if lambdas were deliberately used in code, you could probably infer the types from what it's supposed to be modifying/calling back to in the first place

hollow crane Jun 16, 2020, 5:40 PM

#

yeah that's my view, it's more like a block of a code than a function

flat gazelle Jun 16, 2020, 5:40 PM

#

generally, you pass them as args, and that arg has a Callable[...] type

rich wharf Jun 16, 2020, 5:41 PM

#

alright

crystal pebble Jun 16, 2020, 5:42 PM

#

Do you mean like something like:

    return comp (f, g)

h = compose(print, id)```?

flat gazelle Jun 16, 2020, 5:43 PM

#

no, I mean literally

def id(a): return a
``` but in the builtins somehow. Kind of like `int` and `int.conjugate` are identity functions for ints

crystal pebble Jun 16, 2020, 5:44 PM

#

https://stackoverflow.com/questions/8748036/is-there-a-builtin-identity-function-in-python#8748146

Stack Overflow

Is there a builtin identity function in python?

I'd like to point to a function that does nothing:

def identity(*args)
return args
my use case is something like this

try:
gettext.find(...)
...
_ = gettext.gettext
else:
_ =

#

Looks like there is not

#

That answer is 8-years old though

flat gazelle Jun 16, 2020, 5:46 PM

#

probably there is none. Shame

#

would let you make something entirely with decorators

radiant fulcrum Jun 16, 2020, 6:17 PM

#

built in no

#

but doesnt the identify module have that?

raven pike Jun 16, 2020, 6:45 PM

#

is c++ return void is the same as python return None ?

#

or we dont return anything at all is the equivalent?

flat gazelle Jun 16, 2020, 6:48 PM

#

every function in python returns something, None by default. C++ void means the function does not have a result

#

so they are not the same thing, but you would return None (or just return) in places where you would use void in C++

raven pike Jun 16, 2020, 6:49 PM

#

just "return" works? wow

flat gazelle Jun 16, 2020, 6:51 PM

#

you can also do

def fun():
    print('a')
print(fun())
``` and get
a
None
printed

red solar Jun 16, 2020, 7:13 PM

#

@raven pike are you coming from c++?

raven pike Jun 16, 2020, 7:13 PM

#

@red solar yeah, but i was not professional 🙂

#

some basic oop stuff

red solar Jun 16, 2020, 7:14 PM

#

ah, imagine it more like all objects are pointers (they are in cpython), and None is just nullptr (it's not)

raven pike Jun 16, 2020, 7:14 PM

#

😄 i'm still not over pointers. i mean not seeing them makes me always think

red solar Jun 16, 2020, 7:14 PM

#

in cpython everything is Py_Object* 🤷 (and all functions return Py_Object*, maybe there's some exceptions for special stuff like coroutines)

#

so you can still pretend you live in a land of pointers

wide shuttle Jun 16, 2020, 7:15 PM

#

This is a good video to watch when you're coming from a different language: https://www.youtube.com/watch?v=_AEJHKGk9ns

YouTube

PyCon 2015

Ned Batchelder - Facts and Myths about Python names and values - Py...

"Speaker: Ned Batchelder

The behavior of names and values in Python can be confusing. Like many parts of Python, it has an underlying simplicity that can be hard to discern, especially if you are used to other programming languages. Here I'll explain how it all works, and pre...

▶ Play video

#

It explains how names and values work in Python really well

raven pike Jun 16, 2020, 7:16 PM

#

doesn't __ things mean don't touch that?

#

or am i missing something

#

when looking at the preview

red solar Jun 16, 2020, 7:16 PM

#

it's python you can touch everything

raven pike Jun 16, 2020, 7:16 PM

#

i'm afraid 😄

flat gazelle Jun 16, 2020, 7:16 PM

#

in python __name__ is a dunder

red solar Jun 16, 2020, 7:16 PM

#

we have no access specifiers

flat gazelle Jun 16, 2020, 7:16 PM

#

they have a special meaning when used within classes

#

feel free to touch them

#

in fact, you must touch them in order to make class fields

red solar Jun 16, 2020, 7:17 PM

#

if you're coming from c++, i wouldn't worry about lack of pointers so much as lack of destructors

raven pike Jun 16, 2020, 7:18 PM

#

i'm always worried that if my ram would run out 😛 😄

red solar Jun 16, 2020, 7:19 PM

#

when int() takes a minimum of 24 bytes, thoughts of ram kinda fly out the window

raven pike Jun 16, 2020, 7:21 PM

#

i like your avatar, did you make it yourself? @red solar

#

😄

red solar Jun 16, 2020, 7:21 PM

#

a while back another msging app introduced video profiles, and i asked a friend to send me a few looping gifs, and i chose this one 🙂 (so no)

wide shuttle Jun 16, 2020, 7:22 PM

#

doesn't __ things mean don't touch that?
@raven pike

I think there are two things at play here:

Single and double leading underscores are used to indicate private attributes, with __attribute being a stronger indication that also adds some "name mangling"
double leading and trailing underscores ("dunders"), like __name__ are given to names/attributes that have a special meaning in Python/the Python data model

raven pike Jun 16, 2020, 7:23 PM

#

so _name_ are safe?

wide shuttle Jun 16, 2020, 7:23 PM

#

A lot of those dunders allow you to implement your own classes of objects that behave much like built-ins and that can hook into many parts of the language

#

You shouldn't create your own; it has a very special meaning

#

But, you will typically implement the ones that exist

#

Like __init__ or __len__ or __repr__

flat gazelle Jun 16, 2020, 7:24 PM

#

__name__ does not mean absolutely never touch this, probably compiler specific like in C/C++.

peak spoke Jun 16, 2020, 7:24 PM

#

You probably shouldn't be accessing them directly most of the time because builtins or modules have ways of accessing them. The only real thing you shouldn't do is use their names for your own things or things may break if python does end up using them, and is confusing

red solar Jun 16, 2020, 7:25 PM

#

in general where in c++ we have operator... or constructors, in python we have __magic__

#

so like operator+ would be __add__ (i think)

#

and while (like in c++) you can access them through magic, usually you use the corresponding operator or function

paper echo Jun 16, 2020, 7:33 PM

#

Importantly dunders are not fully polymorphic like c++ operators

red solar Jun 16, 2020, 7:34 PM

#

c++ operators are polymorphic?

paper echo Jun 16, 2020, 7:34 PM

#

Can't you change the meaning of + depending on operands?

#

Or am I thinking of R

red solar Jun 16, 2020, 7:35 PM

#

thats function overloading, not polymorphism

paper echo Jun 16, 2020, 7:35 PM

#

Right

crystal pebble Jun 16, 2020, 7:35 PM

#

You can do operator overloading, but I don't think you can change types

paper echo Jun 16, 2020, 7:36 PM

#

In any case dunder methods on classes only dispatch on the class they're defined on

crystal pebble Jun 16, 2020, 7:36 PM

#

So + for some type has to return that same type

paper echo Jun 16, 2020, 7:36 PM

#

Interesting

red solar Jun 16, 2020, 7:36 PM

#

ok i'm confused, king areyou talking about python or c++?

crystal pebble Jun 16, 2020, 7:36 PM

#

https://en.cppreference.com/w/cpp/language/operators

operators

paper echo Jun 16, 2020, 7:36 PM

#

Anyway thats why you have __add__ and __radd__ in Python

#

When I said polymorphism I meant multiple dispatch

red solar Jun 16, 2020, 7:38 PM

#

ah yeah

#

there's no __ladd__? 😦

paper echo Jun 16, 2020, 7:39 PM

#

Actually wait, multiple dispatch is for run time?

red solar Jun 16, 2020, 7:39 PM

#

i think so

paper echo Jun 16, 2020, 7:39 PM

#

__add__ is ladd

red solar Jun 16, 2020, 7:39 PM

#

oh lol

paper echo Jun 16, 2020, 7:39 PM

#

That's my point, those methods are not symmetric

#

a + b is a.__add__(b), or b.__radd__(a) if a has no __add__ method

red solar Jun 16, 2020, 7:41 PM

#

huh ok we actually have multiple dispatch

paper echo Jun 16, 2020, 7:41 PM

#

Finally falling back to built in +

#

Yeah, this is a hack to implement multiple dispatch on selected binary operators

wide shuttle Jun 16, 2020, 7:43 PM

#

Yeah. (__add__ may also return the NotImplemented singelton to indicate that it doesn't implement it for this combination of a and b)

paper echo Jun 16, 2020, 7:43 PM

#

Interesting

#

I always wondered what that was for

#

https://eli.thegreenplace.net/2016/a-polyglots-guide-to-multiple-dispatch/ anyway time to read up before I get my terminology any more confused

red solar Jun 16, 2020, 7:47 PM

#

if __add__ returns NotImplemented, does the interpreter than try to run __radd__?

wide shuttle Jun 16, 2020, 7:47 PM

#

yeah

#

NotImplemented

This type has a single value. There is a single object with this value. This object is accessed through the built-in name NotImplemented. Numeric methods and rich comparison methods should return this value if they do not implement the operation for the operands provided. (The interpreter will then try the reflected operation, or some other fallback, depending on the operator.) Its truth value is true.

See Implementing the arithmetic operations for more details.

#

!e

class Foo():
    def __init__(self, value):
        self.value = value

    def __add__(self, other):
        return NotImplemented

    def __repr__(self):
        return f"Foo(value={self.value})"


class Bar():
    def __init__(self, value):
        self.value = value

    def __radd__(self, other):
        return self.value + other.value

    def __repr__(self):
        return f"Bar(value={self.value})"


one = Foo(1)
two = Bar(2)

print(one + two)

fallen slateBOT Jun 16, 2020, 7:53 PM

#

@wide shuttle :white_check_mark: Your eval job has completed with return code 0.

red solar Jun 16, 2020, 7:54 PM

#

the only part i don't agree with is it being True why wouldn't it be False

#

like the name starts with Not

peak spoke Jun 16, 2020, 7:55 PM

#

It is the default

#

You're most probably not going to be using the truthy value of it in any way, so there's no reason to provide a non default value

grave jolt Jun 16, 2020, 8:13 PM

#

thats function overloading, not polymorphism
Isn't overloading just ad hoc polymorphism?

#

(as opposed to parametric polymorphism, which is called polymorphism in OOP)

unkempt rock Jun 16, 2020, 9:09 PM

#

How would I go about creating polymorphic code and what are some uses?

crystal pebble Jun 16, 2020, 9:17 PM

#

@unkempt rock https://ocharles.org.uk/blog/guest-posts/2014-12-18-rank-n-types.html

#

I think that has some good explanations of when and why you would want to use polymorphic code

modern frigate Jun 16, 2020, 10:16 PM

#

@mental totem Do ik you?

mental totem Jun 16, 2020, 10:19 PM

#

yep

#

we went to school together

#

franklin

#

lmao

#

you where the drone kid

#

@modern frigate

modern frigate Jun 16, 2020, 10:20 PM

#

indeed

boreal umbra Jun 16, 2020, 10:44 PM

#

I'm trying to think of the most elegant way to define how instances of a certain class are sorted.

#

but don't you basically have to implement __lt__ and __gt__ for each class?

somber halo Jun 16, 2020, 10:45 PM

#

and __eq__ I believe. Seems to be a way to me.

peak spoke Jun 16, 2020, 10:45 PM

#

I believe you only need the lt

boreal umbra Jun 16, 2020, 10:46 PM

#

I wish there was a __key__ dunder that gets used for sorting if it's defined.

#

so I could do

#

def __key__(self):
    return (self.a, self.b, self.c)

#

etc

#

would also make it easier if you need it to work recursively.

#

so if self.a isn't a builtin type, it could use __key__ for that class if it's defined, otherwise try __le__.

languid mesa Jun 16, 2020, 10:48 PM

#

ok not sure if this is the right place to put this but #python-discussion has been muted so... does anyone know a good place to learn matplotlib? i've found the docs but for python i'm not great at learning from docs cuz i'm not great at python

#

a good but relatively brief intro into the module that will help me get my feet wet before i dive into the docs would be great

peak spoke Jun 16, 2020, 10:51 PM

#

That feels like abstracting a lot, implementing lt isn't horribly inconvenient and makes sense in the context

#

things like min also use the key arg in a simliar fashion so you'd cause confusion there

deft pagoda Jun 16, 2020, 10:52 PM

#

theres a @total_order decorator somewhere

north root Jun 16, 2020, 10:52 PM

#

functools.total_order

boreal umbra Jun 16, 2020, 10:52 PM

#

I ended up making a base class for all these classes, and I'll make __key__ an abstract method and make __le__ use whatever that function returns

peak spoke Jun 16, 2020, 10:52 PM

#

believe that's total_ordering, but it's unnecessary for sort

deft pagoda Jun 16, 2020, 10:53 PM

#

https://docs.python.org/3.8/library/functools.html#functools.total_ordering

north root Jun 16, 2020, 10:53 PM

#

you just have to define __lt__ i think with total_ordering, but sort only uses __lt__ anyway i believe

deft pagoda Jun 16, 2020, 10:53 PM

#

yes

peak spoke Jun 16, 2020, 10:53 PM

#

Just feels like complicating stuff more, and making your own dunder also isn't very nice

deft pagoda Jun 16, 2020, 10:54 PM

#

why wouldn't you just define __lt__

#

what am i missing

boreal umbra Jun 16, 2020, 10:56 PM

#

let me paste the code

#

!paste

#

https://paste.pythondiscord.com/afazohisuh.py

#

I didn't actually make each class a subclass of the first one yet

#

I'm very quickly approaching inheritance-as-code-obfuscation territory

peak spoke Jun 16, 2020, 10:58 PM

#

Your last class will just error out

boreal umbra Jun 16, 2020, 10:58 PM

#

it's not done

peak spoke Jun 16, 2020, 11:00 PM

#

I don't really see much use for your key as comparing stuff thruogh random types doesn't make much sense. I'm also not sure why you're changing your lists to be tuples when they're both sequences of arbitrary items

deft pagoda Jun 16, 2020, 11:00 PM

#

dataclasses have a order=True kw

crystal pebble Jun 16, 2020, 11:00 PM

#

@peak spoke What do you think looks cleaner?

#

(Sorry, one sec)

boreal umbra Jun 16, 2020, 11:01 PM

#

@peak spoke I'm trying to make a framework for interacting with certain text data and I want people to be able to modify it to their liking

crystal pebble Jun 16, 2020, 11:02 PM

#

getMatche = dimap matchPairs (bestMatch . sortMatches) validMatches
  where sortMatches  = sortBy (\mA mB -> compare (matchConf mA) (matchConf mB))
        validMatches = filter (getPredicate pMatchTest) . map buildMatch
        bestMatch m  | null m    = Nothing
                     | otherwise = Just (head m)```
vs ```haskell
getMatch = dimap matchPairs bestMatch validMatches
  where validMatches = filter (getPredicate pMatchTest) . map buildMatch
        bestMatch m  | null m    = Nothing
                     | otherwise = Just (maximum m)```

#

I think the second one looks cleaner and the added quality is worth the few extra lines you need to write

peak spoke Jun 16, 2020, 11:03 PM

#

Not sure what I'm supposed to be looking at

crystal pebble Jun 16, 2020, 11:03 PM

#

😦

#

Basically, I think a few extra lines of codes in order to define how to order things is a great abstraction if you plan on sorting in more than one place

#

I wanted to show you an example but that's the only one I have on hand

#

(The key thing to note here is in the top one I had make a sort function on the spot or to have a function somewhere that can be called upon. The alternative to this is make ordering a of our class so that we can just use the same sort function we use everywhere else and ignore the little details about what we're sorting over)

void sonnet Jun 16, 2020, 11:15 PM

#

thoughts on imports at a lower level (not top of module; in a function/method), after sys.path has been modified? i've seen it in the wild, but it just feels dirty.

i just am in a spot where i need to clone a repo that contains a module i need to use, which may change with the commit ref i'm cloning (this is a CI/testing situation).

viral hawk Jun 16, 2020, 11:16 PM

#

Sometimes you need a conditional import- is that such a crime?

#

I often want to avoid an unnecessary dependency while giving users a choice of - for instance - low-level IO library. So if you don’t pass in your “SPI” instance, it imports a library and sets up a default.

#

Actually used this as a crutch to do testing by using a custom IO class that emulated hardware more thoroughly than a mock object could. Have since learned more about mocking.

void sonnet Jun 16, 2020, 11:26 PM

#

yeah, i've had plenty of instances of that in smaller interpreters (CircuitPython, which is actually what i'm testing). the constraints there have always been able to override my "its dirty" thoughts. just never personally used it in less-constrained environments. i've seen it a couple places in CPython projects, just not sure how wide-spread it is or how acceptable.

raven ridge Jun 17, 2020, 1:07 AM

#

@void sonnet In CPython projects it's usually used as a dirty trick to break circular imports, a la https://stackabuse.com/python-circular-imports/

#

perhaps also to delay the cost of loading an expensive module until it's actually needed, but in my experience that's rarer than doing it to break a circular dependency.

deep storm Jun 17, 2020, 1:25 AM

#

Does anyone know how to cast a python integer to a C integer? Possibly with cython?

peak spoke Jun 17, 2020, 1:26 AM

#

For what use?

deep storm Jun 17, 2020, 1:27 AM

#

i need to send a c int into sdl2 to change the keyboard output for android and ios

#

0 = UIKeyboardTypeDefault

#

4 = UIKeyboardTypeNumberPad

#

ect

peak spoke Jun 17, 2020, 1:28 AM

#

This may be better suited to an another channel but should it do that itself? There's always ctypes for something builtin if it's necessary

deep storm Jun 17, 2020, 1:28 AM

#

well the numbers come from python. i could assign them at a lower level in cython

#

but i thought it should be trivial to cast a python int as a cdef int but maybe its not

raven ridge Jun 17, 2020, 1:36 AM

#

it happens implicitly, in fact. if you declare a C function as taking an int in a cdef extern block, then Cython will automatically cast a Python int to a C int when you try to call it. See https://cython.readthedocs.io/en/latest/src/userguide/external_C_code.html#external-c-code

void sonnet Jun 17, 2020, 1:47 AM

#

@raven ridge thanks. luckily, i'm not in a circular import. its really just a deferment since i have to wait until i have the "desired" version of the module.

true hollow Jun 17, 2020, 6:55 AM

#

Are async/await considered keywords in Python 3?

grave jolt Jun 17, 2020, 6:56 AM

#

Well, it depends on the version.

#

Before they were added, they weren't keywords.

true hollow Jun 17, 2020, 6:57 AM

#

Python 3.8?

grave jolt Jun 17, 2020, 6:57 AM

#

📎 unknown.png

wide shuttle Jun 17, 2020, 6:57 AM

#

They were only upgraded to keywords in 3.7, I think

true hollow Jun 17, 2020, 6:57 AM

#

oooooh

#

cool

wide shuttle Jun 17, 2020, 6:57 AM

#

async and await names will be softly deprecated in CPython 3.5 and 3.6. In 3.7 we will transform them to proper keywords. Making async and await proper keywords before 3.7 might make it harder for people to port their code to Python 3.

grave jolt Jun 17, 2020, 6:58 AM

#

Yep

true hollow Jun 17, 2020, 6:58 AM

#

~~damn, soo many keywords~~

grave jolt Jun 17, 2020, 6:58 AM

#

Because if someone had named their variable await or async, making them keywords right away would be a breaking change.

true hollow Jun 17, 2020, 6:58 AM

#

yeah

grave jolt Jun 17, 2020, 6:58 AM

#

!e

import keyword
print(keyword.kwlist)

fallen slateBOT Jun 17, 2020, 6:58 AM

#

@grave jolt :white_check_mark: Your eval job has completed with return code 0.

['False', 'None', 'True', 'and', 'as', 'assert', 'async', 'await', 'break', 'class', 'continue', 'def', 'del', 'elif', 'else', 'except', 'finally', 'for', 'from', 'global', 'if', 'import', 'in', 'is', 'lambda', 'nonlocal', 'not', 'or', 'pass', 'raise', 'return', 'try', 'while', 'with', 'yield']

grave jolt Jun 17, 2020, 6:59 AM

#

As you can see, there are keywords!

true hollow Jun 17, 2020, 6:59 AM

#

i didn't know that module exists lol

#

today I learned something new! yay

wide shuttle Jun 17, 2020, 6:59 AM

#

It's pretty middle of the road as far as the number of keywords go

#

This answer on SO has a comparison; I haven't checked it: https://stackoverflow.com/a/4980785

brave badger Jun 17, 2020, 7:47 AM

#

@rich wharf Re: #help-avocado
Here's a hacky implementation that I wrote
https://gist.github.com/PureFunctor/cd1c40d65ee08345cd51cb6aabd662c1

Gist

attrfunc.py

GitHub Gist: instantly share code, notes, and snippets.

#

Though if the properties of the decorator are supposed to be passed to the method, that's also different

red solar Jun 17, 2020, 8:24 AM

#

TypeError: argument 1 must be , not int

#

tf do i do now

#

is this a normal error?

#

ah it's me being dumb and not properly reading documentation

#

yay it works 🙂

unkempt rock Jun 17, 2020, 8:45 AM

#

get gud

magic python Jun 17, 2020, 10:25 AM

#

when debugging one can trigger an ipython session - within this session variables which are in memory can't be used in list comprehensions, does anyone know why that is?

hollow crane Jun 17, 2020, 10:25 AM

#

what error do you get

#

like what happens

magic python Jun 17, 2020, 10:30 AM

#

says that it's not found

#

if you have some list l that you can see with just l <ret>, you won't be able to do [x for x in l if x > 3] or whatever

flat gazelle Jun 17, 2020, 10:33 AM

#

does l[0], [*l] and such work?

hollow crane Jun 17, 2020, 10:57 AM

#

what about vars["l"]

magic junco Jun 17, 2020, 11:50 AM

#

Are python lists arrays?

flat gazelle Jun 17, 2020, 11:50 AM

#

In the background yes.

magic junco Jun 17, 2020, 11:51 AM

#

but you can't store multiple data types in an array

#

how does python do that?

flat gazelle Jun 17, 2020, 11:51 AM

#

They are all the same type, PyObject *

peak spoke Jun 17, 2020, 11:52 AM

#

They're arrays of pointers to the python objects, so it's still one type

magic junco Jun 17, 2020, 11:52 AM

#

does this mean that string and integers are all the same type in python?

flat gazelle Jun 17, 2020, 11:54 AM

#

They are both python objects, but they do have some specific properties as well afaik

magic junco Jun 17, 2020, 11:56 AM

#

I see, thank you

gloomy rain Jun 17, 2020, 12:05 PM

#

So that means there's no way to store, say, an array of integers side by side in memory? I mean, without calling into some C library?

flat gazelle Jun 17, 2020, 12:13 PM

#

not that I am aware of, you would need to use something like the builtin array library

red solar Jun 17, 2020, 1:23 PM

#

import ctypes

ten_int_array = ctypes.c_int * 10
for i in range(len(ten_int_array)):
    ten_int_array[i] = i

#

if array is too boring 🙂

hasty thistle Jun 17, 2020, 1:42 PM

#

🤔

flat gazelle Jun 17, 2020, 1:43 PM

#

you can also use bytearray for just 1 byte unsigned ints

red solar Jun 17, 2020, 2:19 PM

#

does python not have atomic types?

hollow crane Jun 17, 2020, 2:30 PM

#

like what

#

it doesn't have fixed size atomic types by default

#

as in a char or an unsigned long or something

red solar Jun 17, 2020, 2:30 PM

#

i don't want to use a mutex for a single int :/

hollow crane Jun 17, 2020, 2:30 PM

#

for hinting?

red solar Jun 17, 2020, 2:30 PM

#

no for thread safety

hollow crane Jun 17, 2020, 2:30 PM

#

oh wait

#

yeah

#

seems like a common problem

#

maybe python's atomics are threadsafe

#

idk

#

or like in assignment

red solar Jun 17, 2020, 2:31 PM

#

python has atomics?

#

the only thing i can think of is x = y is atomic, and then if y changes, x won't

#

(and technically it's only atomic on some platforms)

timid orbit Jun 17, 2020, 2:32 PM

#

Joe said this might fit here; Any ideas?

📎 Screenshot_20200617_163205.png

red solar Jun 17, 2020, 2:32 PM

#

oh yay just been doing this 🙂

timid orbit Jun 17, 2020, 2:33 PM

#

I've also tried using a void* as struct member, but that led tho this: cpp src/py_nitro_emulator.cpp: In function ‘int NitroEmulator_Init(PyObject_NitroEmulator*, PyObject*, PyObject*)’: src/py_nitro_emulator.cpp:8:33: error: expected type-specifier before ‘nitro_emulator’ 8 | self->emulator = (void*)new nitro_emulator(); | ^~~~~~~~~~~~~~

red solar Jun 17, 2020, 2:33 PM

#

it's header only?

timid orbit Jun 17, 2020, 2:33 PM

#

it's not; I'm trying to write an extension for a Cpp lib but it uses classes

red solar Jun 17, 2020, 2:34 PM

#

are you linking the cpp file? (the nitro one)

timid orbit Jun 17, 2020, 2:34 PM

#

I am

red solar Jun 17, 2020, 2:35 PM

#

have you defined tp_alloc, tp_new or tp_init?

timid orbit Jun 17, 2020, 2:35 PM

#

# setup.py

import glob
from setuptools import setup, Extension

setup(
    name="libnitro_native",
    ext_modules=[
        Extension('libnitro_native',
                  sources=(glob.glob("src/*.c") +
                           glob.glob("src/*.cpp") +
                           glob.glob("../../src/*.cpp")),  # libnitro source; I'll set up linking later
                  include_dirs=["include/",
                                "../../include/"],  # libnitro headers
                  language='c++')
    ]
)

red solar Jun 17, 2020, 2:35 PM

#

also does python allow c++ classes? even with c++ linkage?

timid orbit Jun 17, 2020, 2:36 PM

#

the issue is that nitro_emulator somehow isn't found by the compiler and I have no clue why

lost nexus Jun 17, 2020, 2:38 PM

#

is there any other advantages to double assignment over tuple unpacking (for assigning the same value to multiple names)? I know some compilers do this in auto-optimization and that one-less instruction doesn't really matter with modern cpus.

timid orbit Jun 17, 2020, 2:39 PM

#

@lost nexus if you provide two samples I can look into what's faster and why

red solar Jun 17, 2020, 2:39 PM

#

@timid orbit can you try running the command python3 setup.py build executed but with g++ instead of gcc?

timid orbit Jun 17, 2020, 2:39 PM

#

I wouldn't know how to make python select g++

red solar Jun 17, 2020, 2:39 PM

#

no just copy paste what it did

#

but with g++

lost nexus Jun 17, 2020, 2:40 PM

#

one = one_aswell = 1
# load 1
# store one
# store one_aswell

(one, one_aswell) = (1, 1)
# load 1
# load 1
# store one
# store one_aswell

timid orbit Jun 17, 2020, 2:41 PM

#

same error with g++

red solar Jun 17, 2020, 2:41 PM

#

damn :/

flat gazelle Jun 17, 2020, 2:41 PM

#

In [12]: dis.dis('one = one_aswell = 1')
  1           0 LOAD_CONST               0 (1)
              2 DUP_TOP
              4 STORE_NAME               0 (one)
              6 STORE_NAME               1 (one_aswell)
              8 LOAD_CONST               1 (None)
             10 RETURN_VALUE

In [13]: dis.dis('(one, one_aswell) = (1, 1)')
  1           0 LOAD_CONST               0 ((1, 1))
              2 UNPACK_SEQUENCE          2
              4 STORE_NAME               0 (one)
              6 STORE_NAME               1 (one_aswell)
              8 LOAD_CONST               1 (None)
             10 RETURN_VALUE
``` there is a difference

peak spoke Jun 17, 2020, 2:42 PM

#

Well there's no need to use unpacking there where you can just store two names

flat gazelle Jun 17, 2020, 2:42 PM

#

though do note that

a, b = [], []
``` and ```py
a = b = []
``` are different

lost nexus Jun 17, 2020, 2:42 PM

#

i know

timid orbit Jun 17, 2020, 2:42 PM

#

DUP_TOP is a lot faster than UNPACK_SEQUENCE

peak spoke Jun 17, 2020, 2:43 PM

#

Python is really too high level to worry about cpu instructions (and in most applications lower level languages too)

red solar Jun 17, 2020, 2:43 PM

#

c++ is fine to worry about asm

lost nexus Jun 17, 2020, 2:43 PM

#

@peak spoke i know i'm just curious if there's any other advantages

flat gazelle Jun 17, 2020, 2:44 PM

#

optimizing bytecode is good as in it speeds things up. But generally at that point you will be better off using FFI

lost nexus Jun 17, 2020, 2:44 PM

#

FFI?

flat gazelle Jun 17, 2020, 2:44 PM

#

foreign function interface, the way to call C stuff

fallen slateBOT Jun 17, 2020, 2:44 PM

#

Hey @timid orbit!

It looks like you tried to attach file type(s) that we do not allow (.zip). We currently allow the following file types: .3gp, .3g2, .avi, .bmp, .gif, .h264, .jpg, .jpeg, .m4v, .mkv, .mov, .mp4, .mpeg, .mpg, .png, .tiff, .wmv, .svg, .psd, .ai, .aep, .xcf, .mp3, .wav, .ogg.

Feel free to ask in #community-meta if you think this is a mistake.

lost nexus Jun 17, 2020, 2:44 PM

#

ic

timid orbit Jun 17, 2020, 2:44 PM

#

:(

peak spoke Jun 17, 2020, 2:45 PM

#

Just worry about what's more readable while keeping your behaviour

timid orbit Jun 17, 2020, 2:45 PM

#

will dm source @red solar

lost nexus Jun 17, 2020, 2:45 PM

#

what do you see as more readable

peak spoke Jun 17, 2020, 2:45 PM

#

in the case of immutables the multiple assignment is probably more readable than unpacking, and if you need to do it for something longer it'll be better to just do it on separate lines

lost nexus Jun 17, 2020, 2:46 PM

#

yeah

rich wharf Jun 17, 2020, 5:23 PM

#

thanks @brave badger

red solar Jun 17, 2020, 5:35 PM

#

is there a way to synchronize objects in shared memory? do i literally need a lock?

#

there's no lock free way?

#

ok ig moving on cuz i can't find anything online

#

if we had atomic, would it be atomic.long, atomic.Long, or atomic.AtomicLong? (ok probably can't be the first one because with atomic.int, from atomic import * would cause it to clash with int())

unkempt rock Jun 17, 2020, 5:51 PM

#

thats why you dont from x import *

red solar Jun 17, 2020, 5:51 PM

#

yeah but you know someone's going to do it lol

unkempt rock Jun 17, 2020, 5:51 PM

#

thats their own fault IMO

red solar Jun 17, 2020, 5:52 PM

#

maybe, but i'm not gonna shoot them in the foot for slightly misusing a language feature 😂

#

so Long or AtomicLong?

unkempt rock Jun 17, 2020, 5:53 PM

#

that i have no clue ;-;

red solar Jun 17, 2020, 5:53 PM

#

damn :/

unkempt rock Jun 17, 2020, 5:55 PM

#

from pynput.keyboard import Key, Controller
import time

keyboard = Controller()

time.sleep(2)

for char in "wwwwww":
    keyboard.press(char)
    print(char + " was pressed")
    time.sleep(0.02)

so basically this code works fine h
however when I enter a game the player doesnt move forward or whatever
how can I fix this? I made sure the code ran
pls help

true hollow Jun 17, 2020, 6:30 PM

#

@unkempt rock please visit #❓｜how-to-get-help 🙂
this channel is to talk and discuss about PEPs, implementation of the python language, the future of the python language and etc

#

you can read more about this on this channel's topic

unkempt rock Jun 17, 2020, 6:34 PM

#

oh

raven pike Jun 17, 2020, 6:50 PM

#

do you guys think python should borrow series from pandas?

#

i mean it's like lists but different you know, and it might be so valuable to so many libraries and people ofc

paper echo Jun 17, 2020, 6:55 PM

#

i think not

#

series isn't just a data structure

#

it comes with a huge amount of functionality

#

adding anything to the standard library at this point deserves very very careful consideration

cedar nimbus Jun 17, 2020, 6:59 PM

#

where i can find a list of all global variables that python makes such as __name__?

charred wagon Jun 17, 2020, 7:01 PM

#

Probably here https://docs.python.org/3/reference/datamodel.html

#

Under the "modules" section

#

This may have it too https://docs.python.org/3/reference/import.html#importsystem

red solar Jun 17, 2020, 7:08 PM

#

@paper echo why?

#

i wanna add atomics :/

raven pike Jun 17, 2020, 7:08 PM

#

@paper echo not the functionality, the structure. just leave something like _init_ for people to customize it themselves

paper echo Jun 17, 2020, 7:08 PM

#

what's the point then?

#

python already has array.array

#

what's an atomic? @red solar

raven pike Jun 17, 2020, 7:09 PM

#

can arrays be appended?

#

i meant non-numeric functions, but series like functions should be implemented

red solar Jun 17, 2020, 7:09 PM

#

an atomic is an object on which operations are indivisible (so thread safe)

paper echo Jun 17, 2020, 7:10 PM

#

@raven pike i just dont see the point

#

other than "making python itself bigger, harder to re-implement, and harder to test/maintain"

raven pike Jun 17, 2020, 7:11 PM

#

maybe i'm over-thinking

paper echo Jun 17, 2020, 7:11 PM

#

when we already have well-established powerful libraries doing this stuff

#

if anything we should be deprecating old things in the stdlib like the http parser, xml parser, etc. and handing them off to 3rd parties willing to do their own maintenance. but that's a somewhat extreme opinion

#

@red solar i think that's the whole point of the GIL, so good luck with that one 😛

raven pike Jun 17, 2020, 7:13 PM

#

shouldn't there be an initiative first? i mean someone should make something like these parsers; then they can hand it over.
cutting them in order to make community take care of them is sounding like a harsh solution as you put

paper echo Jun 17, 2020, 7:17 PM

#

i think thats backwards

#

libraries get popular, then they get funding by some big organization like the PSF or NumFocus or Pydata

red solar Jun 17, 2020, 7:18 PM

#

GIL doesn't help if i want to put my object in shared memory

paper echo Jun 17, 2020, 7:18 PM

#

what language has atomics? c++?

raven pike Jun 17, 2020, 7:19 PM

#

also asked in general but this place seems more appropriate for this one:
how i can retrieve a type stub file? for example for pandas, where can i get it? or everyone doing custom ones for themselves?

paper echo Jun 17, 2020, 7:19 PM

#

id just be curious what an "atomics" library looks like

raven pike Jun 17, 2020, 7:19 PM

#

@paper echo that's kind of scary, orgs behind these; then they might disappear one day?

red solar Jun 17, 2020, 7:19 PM

#

you don't want to see c/c++'s one - you won't understand a word of it (i don't)

paper echo Jun 17, 2020, 7:19 PM

#

the PSF might disappear too 🤷‍♂️

red solar Jun 17, 2020, 7:19 PM

#

what parsers?

raven pike Jun 17, 2020, 7:20 PM

#

@paper echo 😦

paper echo Jun 17, 2020, 7:20 PM

#

@raven pike you want to physically obtain the .pyi files? or just make sure that mypy can find them?

raven pike Jun 17, 2020, 7:21 PM

#

actually i'm using pyright; and it can't catch lots of things from docstrings

red solar Jun 17, 2020, 7:21 PM

#

thought pandas would be written in c - turns out they just use scipy/numpy :/

peak spoke Jun 17, 2020, 7:21 PM

#

There's typeshed for python, but you'll have to search for other libraries if they didn't make it themselves

paper echo Jun 17, 2020, 7:21 PM

#

@red solar they have some Cython code at the low level

red solar Jun 17, 2020, 7:21 PM

#

where? i'm looking at the github

paper echo Jun 17, 2020, 7:21 PM

#

but yes it's based on Numpy (which is mostly C extensions)

#

there are a few .pyx files in the pandas repo

raven pike Jun 17, 2020, 7:22 PM

#

the official one right?

red solar Jun 17, 2020, 7:22 PM

#

yeah

raven pike Jun 17, 2020, 7:22 PM

#

or are there some community made ones?

paper echo Jun 17, 2020, 7:22 PM

#

pandas has stub files for sure, idk where they are

raven pike Jun 17, 2020, 7:22 PM

#

i downloaded a mypy extension for pandas, but it's full of false-positives

#

science-data-types i guess its name

paper echo Jun 17, 2020, 7:23 PM

#

i never got an extension

#

i just use mypy and it works on pandas stuff

raven pike Jun 17, 2020, 7:23 PM

#

gotcha. do you think chaining might confuse mypy @paper echo

#

like df.drop(...).dropna(...).etcetc

paper echo Jun 17, 2020, 7:24 PM

#

no

#

numpy i think has stub files in the main repo

#

pandas might too somewhere

harsh delta Jun 17, 2020, 7:34 PM

#

any free server to use mqtt portal

#

??

magic python Jun 17, 2020, 8:23 PM

#

i've no idea if there's any reasoning to this... but in path lib there's Path().exists() and in pandas there's pd.DataFrame.empty, they seem to do pretty similar things? Why is the pathlib a method and the pandas an attribute 🤔

#

exists doesn't seem to take an argument, so idk why it can't just be an attribute too... it probably doesn't matter at all, i was just curious

inland acorn Jun 17, 2020, 8:30 PM

#

this is just a guess, but exists is probally calling the system to check it, while empty is just checking values that are in ram. might be wrong on that tho

#

@magic python

magic python Jun 17, 2020, 8:34 PM

#

right, makes sense

magic python Jun 17, 2020, 8:58 PM

#

Is it possible to use a logger across different modules?

#

I guess I'd have to pass it as an argument to them... not worth it perhaps

wide shuttle Jun 17, 2020, 9:06 PM

#

within the same application?

#

You shouldn't have to pass them around

#

Just use:

log = logging.getLogger(<samenamehere>)

#

but usually you want unique names that reflect the hierarchy in your project

#

a common version is

#

log = logging.getLogger(__name__)

magic python Jun 17, 2020, 9:20 PM

#

@wide shuttle same application, I guess? I have a script that calls various other modules to process analysis... though maybe that's just bad design from the start 🤔

paper echo Jun 17, 2020, 9:22 PM

#

i usually pass around loggers, idk why

#

notably if you run something with -m the __name__ changes to '__main__'

magic python Jun 17, 2020, 9:23 PM

#

i've been using loguru ... i think this project is probably an unsalvagable clusterfuck at this point though

gloomy rain Jun 17, 2020, 9:27 PM

#

Passing around loggers sounds like a huge hassle

#

There's a reason why they are considered to be a valid use case for singletons

magic python Jun 17, 2020, 9:38 PM

#

@gloomy rain a singleton means that only one instance of it is created?

raven ridge Jun 17, 2020, 9:39 PM

#

that only one instance can be created, generally.

paper echo Jun 17, 2020, 9:39 PM

#

@gloomy rain i usually do from mymodule.submodule1 import logger as submodule1_logger

#

maybe thats bad style

gloomy rain Jun 17, 2020, 9:39 PM

#

It's an OOP pattern where you design a class in such a way that you can't instantiate it more than once. Not really possible to implement properly in Python, since it doesn't enforce member access control.

magic python Jun 17, 2020, 9:39 PM

#

so mymodule.submodule1 is the "master" script?

raven ridge Jun 17, 2020, 9:40 PM

#

The standard is something like

log = logging.getLogger(__name__)
``` Anything other than that is weird, and makes it harder for users to configure logging for your libraries.

void sonnet Jun 17, 2020, 9:40 PM

#

@paper echo i was doing that. gdude convinced me otherwise.

gloomy rain Jun 17, 2020, 9:40 PM

#

It also essentially makes the one instance a global variable.

paper echo Jun 17, 2020, 9:40 PM

#

yeah i always do that at the top of my module @raven ridge

magic python Jun 17, 2020, 9:40 PM

#

@void sonnet what was the otherwise 😄

paper echo Jun 17, 2020, 9:40 PM

#

i just dont typically use getlogger when i need to get another module's logger, i just import it from that module

#

(at least within an application)

magic python Jun 17, 2020, 9:40 PM

#

I have

from loguru import logger as log

🤔

raven ridge Jun 17, 2020, 9:41 PM

#

you should never get another module's logger - I'm curious how you got into a situation where you wanted to do that in the first place 😄

paper echo Jun 17, 2020, 9:41 PM

#

@raven ridge in __main__.py when i'm configuring output to the console

#

like if i run with a --debug option

peak spoke Jun 17, 2020, 9:41 PM

#

Not unusual in testing

paper echo Jun 17, 2020, 9:41 PM

#

that too ^ to make assertions about log output