Nostr notes by Trey Hunner 🐍

Python Tip #100 (of 365): Prefer the pathlib.Path object's ...

2026-04-10T18:10:04Z

Python Tip #100 (of 365):

Prefer the pathlib.Path object's is_file() and is_dir() methods over exists()

The exists method tells you SOMETHING is there but not WHAT.

Using is_file() or is_dir() is more explicit about what you're actually checking for, and usually what you actually want.

Usually when I find myself using exists(), I'll realize that I wanted one of the more specific methods instead.

#Python #DailyPythonTip

Throwing some financial support toward @npub1vv8…6fhk? ...

2025-11-05T21:20:46Z

Throwing some financial support toward Python Software Foundation (npub1vv8…6fhk)? Excellent!

If you are a #Django user, consider also supporting the DSF.

The Django Software Foundation has been running a fundraiser for the past couple weeks. It ends it 5 days.

https://www.djangoproject.com/weblog/2025/oct/23/pycharm-django-annual-fundraiser/

I am very glad the Python Software Foundation is sticking to ...

2025-10-27T16:55:11Z

I am very glad the Python Software Foundation is sticking to their mission statement.

I'm also bummed that the US government's war on diversity forced the PSF to turn down $1,500,000 of funding.

Imagine if PyLadies and Black Python Devs couldn't have booths at PyCon. Imagine if Charlas and Mentored Sprints for Diverse Beginners couldn't happen. Imagine no PyLadies auction and no funding for meetups that mention diversity. I'm glad we don't live in that world.

https://pyfound.blogspot.com/2025/10/NSF-funding-statement.html

If you had the ability to run some Python code in every Python ...

2025-10-09T03:31:45Z

If you had the ability to run some Python code in every Python REPL launched on your machine what would it do? (Automagically available PyPI dependencies are allowed)

Asking for someone who just realized they are not yet heavily overusing their PYTHONSTARTUP file. (me)

Seriously, I'm looking for ideas. Good ones, bad ones, all ideas welcome.

#Python

Resources for creating #Python packages ...

2025-09-27T18:57:32Z

In reply to nevent1q…eh9p
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Resources for creating #Python packages

A PSA to use pyproject.toml instead of setup.py for #Python ...

2025-09-27T18:46:50Z

In reply to nevent1q…ujj9
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A PSA to use pyproject.toml instead of setup.py for #Python project metadata 📣

Parul Gupta comparing #Python packaging to preparing a gift at ...

2025-09-27T18:37:31Z

Parul Gupta comparing #Python packaging to preparing a gift at #PyBeach

Sad you can't make it to DjangoCon US next week? Me too. ...

2025-09-04T19:45:45Z

Sad you can't make it to DjangoCon US next week?

Me too.

That's why I just bought an online ticket.

You should too! Click "buy tickets" here: https://2025.djangocon.us

See you in the Slack!

#Django #DjangoCon

I am seeking a phrase to describe when someone with strong ...

2025-08-21T14:42:07Z

I am seeking a phrase to describe when someone with strong negative feelings about "LLMs" or "AI" blurts out poorly-thought-out hot takes.

Takes like "if an LLM was able to do it, then it must not be worth doing"

Like the opposite of "AI bro".

Using the description of "AI skeptic" isn't fair to AI skeptics.

Thoughts on names for this phenomenon?

A friend is building an app to help immigrants detained by ICE. ...

2025-06-23T21:08:55Z

A friend is building an app to help immigrants detained by ICE.

It's a web app currently, but is intended to be a mobile app.

Anyone have experience building and deploying mobile apps and interested in volunteering time to help a new app with a good cause?

Feel free to share with others or boost for reach.

Editing to link to the current repository:
https://github.com/habeas-project/habeas

DM me for a Signal username you can use or contact the email at the bottom of the README file.

#AndroidDev #iOSdev

I have a medium fitted #PyConUS and would like to trade for a ...

2025-05-18T21:39:08Z

I have a medium fitted #PyConUS and would like to trade for a medium straight cut. If anyone has the opposite problem let me know tonight!

I also have the same problem with a PyCon 2023 medium fitted shirt I accidentally bought.

I'm considering putting some very simple slides together for ...

2025-05-08T03:11:44Z

I'm considering putting some very simple slides together for a lightning talk soon.

What do you prefer to use for making slides in 2025?

I've updated my "How to have a great first PyCon" ...

2025-04-09T01:08:00Z

I've updated my "How to have a great first PyCon" blog post for 2025.

I linked to more blog posts from others on "how to PyCon", updated links to this year's PyCon website, added more updates around the implosion of Twitter, and updated some outdated references.

See you at #PyConUS! 👋 #Python 🐍💖

https://trey.io/pycon-tips

good question. The pitch I make to my clients for upgrading is ...

2024-12-20T20:01:15Z

In reply to nevent1q…x02f
_________________________

good question. The pitch I make to my clients for upgrading is around being able to use third-party packages, since most drop support for versions that have reached EOL.

This is based on the premise that the EOL date is treated by many package maintainers roughly as "this is when we can stop supporting that Python version", which seems at least partially true.

If there was a date baked-in to the interpreter that many of my ...

2024-12-20T17:12:31Z

In reply to nevent1q…4dsq
_________________________

If there was a date baked-in to the interpreter that many of my students have, in 8 years I could ask everyone to run a command to see when their default python interpreter is supported until.

Telling them to trust me on the supported versions or going to a website that lists the end of life date feels a bit less definitive somehow.

I suspect they may be more likely to convinced to upgrade if the interpreter had its own end of life date baked-in.

I'm imagining that there would either be a requirement that ...

2024-12-20T17:08:21Z

In reply to nevent1q…x8dd
_________________________

I'm imagining that there would either be a requirement that downstream builds customize the date, keep it the same, or set it to None (or delete the value even) if they wanted to explicitly note that no support is promised.

This end of life date is used by user-facing folks already. A user-facing page might be a good idea to note what that date means.

Make context managers with enter & exit Read more ...

2024-12-20T14:45:42Z

Make context managers with __enter__ & __exit__

Read more 👉 https://trey.io/LNesnG

#python

Anyone know whether there's ever been a PEP for storing the ...

2024-12-20T02:00:01Z

Anyone know whether there's ever been a PEP for storing the end of life date for each Python version within Python?

I'm imagining a sys.supported_until datetime object.

I'd love to ask each of my current Python installations whether they're supported rather than looking that information up in online docs.

#Python

I just published a short screencast on the different ways to ...

2024-12-19T21:59:14Z

I just published a short screencast on the different ways to merge dictionaries in Python.

https://pym.dev/merging-dictionaries-in-python/

#Python

True. I'm starting with the assumption of "something that ...

2024-12-19T20:37:18Z

In reply to nevent1q…ax7s
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True. I'm starting with the assumption of "something that can be passed to int/float" (which I don't believe are localize-able).

A .replace(",", ".") could be used for localization.

Thousands separator support could also be added with a .replace("_", ",") (or with "." for countries that use . separators).

But of course, none of this in the right way to accomplish this. 😅

Oh and just to be clear for folks reading this and considering ...

2024-12-19T20:08:47Z

In reply to nevent1q…2w7s
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Oh and just to be clear for folks reading this and considering using isdecimal in your code:

1. isdecimal does also accepts some interesting non-ASCII "decimal" characters, but all of those characters will be accepted by Python's float() and int() functions.

2. I recommend against all the string isdecimal, isdigit, and isnumeric methods because they're confusing and probably not what you actually want. Use a regular expression or (better yet) attempt a conversion and try-except it!

ack. isdecimal() is the one I wanted. (Editing the original ...

2024-12-19T20:01:12Z

In reply to nevent1q…q8j3
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ack. isdecimal() is the one I wanted.

(Editing the original post...)

I always mix up is isdecimal, isdigit, and isnumeric even though I've written about their differences more than a few times now...

I think I just found my least favorite way to accurately check ...

2024-12-19T19:21:01Z

I think I just found my least favorite way to accurately check whether a string (value) represents a number in #Python. 😬

value.removeprefix("-").replace(".", "", 1).isnumeric()

I feel very honored to be selected as a PSF fellow this week ...

2024-12-19T05:32:52Z

I feel very honored to be selected as a PSF fellow this week alongside Jay Miller (npub180d…m4nr) and Kojo Idrissa @ Home (npub18f4…hxlr), who are 2 of the most welcoming folks I know in the Python community. 💖

Jay's post on becoming a fellow: https://kjaymiller.com/blog/on-becoming-a-psf-fellow.html

thanks Elena!

2024-12-19T01:16:20Z

In reply to nevent1q…3xxl
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thanks Elena!

thanks Jeff!

2024-12-18T15:23:12Z

In reply to nevent1q…nyus
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thanks Jeff!

thanks Hugo!

2024-12-18T15:22:50Z

In reply to nevent1q…wsep
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thanks Hugo!

I didn't note that because I haven't look into it. I ...

2024-12-18T14:19:47Z

In reply to nevent1q…4zyc
_________________________

I didn't note that because I haven't look into it.

I don't plan to ever activate those virtual environments, so I don't really care where uv stores them. I'm pretty sure it's in a hidden directory somewhere in my home folder.

The / indicates that every argument before the / is a ...

2024-12-18T11:00:57Z

The / indicates that every argument before the / is a positional-only argument.

Read more 👉 https://trey.io/vrp702

#Python

You can think of the tokenize, ast, and dis modules as ...

2024-12-16T22:53:21Z

You can think of the tokenize, ast, and dis modules as progressively deeper steps in the process of parsing the code in a Python module.

Read more 👉 https://trey.io/9v8gwb

#Python

No offense taken. I hadn't heard of Execute Program before ...

2024-12-16T18:23:27Z

In reply to nevent1q…vqjh
_________________________

No offense taken. I hadn't heard of Execute Program before your post. :)

Yes, Python Morsels does involve spaced repetition in a couple different ways and I'm working on making the repetitions more deliberate than they have been.

great points! Adding that podcast episode to my queue. 👍

2024-12-14T16:02:41Z

In reply to nevent1q…awzd
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great points! Adding that podcast episode to my queue. 👍

yes and no. You'll need to get past the basics at some point, ...

2024-12-13T20:49:16Z

In reply to nevent1q…84xr
_________________________

yes and no.

You'll need to get past the basics at some point, but I often work with folks seeking intermediate-level Python topics that don't yet have a strong grasp of more basic topics.

Knowing what the available tools are and identifying which tool might help in specific scenarios takes time and practice.

I've been thinking about these two problems over the past ...

2024-12-13T19:04:08Z

In reply to nevent1q…9q9l
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I've been thinking about these two problems over the past month and it's inspired a big update this week to the way exercise revisiting works in Python Morsels.

Exercise revisiting has been a Python Morsels feature for a few years, but revisiting the same exercise again feels boring and may sound pointless, so this feature has been severely underused.

As of this week, revisiting an exercise is much more highly encouraged, which I'm hoping will improve learning retention. Time will tell! 🤞

The solutions: • Active recall: attempting to retrieve ...

2024-12-13T19:04:08Z

In reply to nevent1q…e366
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The solutions:

• Active recall: attempting to retrieve information from your head, noting that you'll fail at this often but each attempt (even a failed one) helps make it stick
• Spaced repetition: repeatedly performing active recall, spaced hours, days, and weeks apart to allow time to forget a bit before attempting recall again

Active recall can feel challenging and spaced repetition can feel boring, so successful learning sometimes feels both boring and exhausting... at the same time! 😥

2️⃣ On not enough focus on repetition... So we learn by ...

2024-12-13T19:04:07Z

In reply to nevent1q…qv9v
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2️⃣ On not enough focus on repetition...

So we learn by information retrieval (quizzing, elaborating, doing), but we don't just need to retrieve once.

We learn through "repeated" information retrieval attempts. Learning doesn't typically stick unless we retrieve information repeatedly, spaced out over many days.

Repetition can feel VERY boring. You tried the thing. Maybe you even succeeded at the thing. Now you had to do the same thing again a week later? What?!

1️⃣ On too much focus on consuming information... This is a ...

2024-12-13T19:04:07Z

In reply to nevent1q…k3az
_________________________

1️⃣ On too much focus on consuming information...

This is a common question that I'm always suspicious of:

"What Python book should I read next?"

Our brains learn through repeated information retrieval attempts, not through information consumption.

That could mean quizzing, explaining a concept, or performing an action.

This involves our brain attempting something it can't quite do yet, which can feel VERY challenging, but minute-by-minute it's usually MUCH more productive than re-reading.

Learning a new skill? I bet you're making 2 big mistakes. 1. ...

2024-12-13T19:04:06Z

Learning a new skill? I bet you're making 2 big mistakes.

1. You're focusing too much on consuming information
2. You're not focusing enough on repetition

I notice new Python learners falling into this trap. It's a big problem with the resources we use to learn and the way we talk about and use those resources.

🧵

#learning #teaching #Python

this is very contextual for me. I often rely on the falsiness of ...

2024-12-10T20:26:06Z

In reply to nevent1q…ugr8
_________________________

this is very contextual for me. I often rely on the falsiness of None, but if a falsey non-None value could be valid as well, I definitely use an "x is None" check.

I understand the truthiness over True-checking recommendation but ...

2024-12-10T17:55:38Z

In reply to nevent1q…kl6t
_________________________

I understand the truthiness over True-checking recommendation but I've always ignored the "is True" is worse than "== True" note. The only time I check for exactly True is in tests and I *want* and I identity check in that case.

I'd be curious what the history/reasoning behind "is True being worse than "== True" is.

Why do we use "is" when checking for None in Python? 2 ...

2024-12-10T16:43:00Z

Why do we use "is" when checking for None in Python?

2 reasons you'll hear:

1. Python objects can overload "==" but not "is" so an object could say it's equal to None but "is" will only check for the (one and only) None
2. Using "is" doesn't even look at the object, but only looks at its memory location so it's technically faster

I don't find those reasons convincing, but I DO use "is" to check for None.

Why?

PEP 8.

I don't have a decent reason for bucking convention, so I stick with it.

this is exactly the reason I asked. I suspect it may be overused ...

2024-12-10T15:27:20Z

In reply to nevent1q…7cdy
_________________________

this is exactly the reason I asked. I suspect it may be overused in unfortunate ways.

that's a good one too. It does seem like "the original ...

2024-12-10T15:26:17Z

In reply to nevent1q…mhhl
_________________________

that's a good one too. It does seem like "the original error is an unimportant implementation detail" is the clearest use.

interesting. So the line and column number of the decode ...

2024-12-10T04:41:57Z

In reply to nevent1q…pdty
_________________________

interesting. So the line and column number of the decode weren't useful in your case, I assume because it wasn't even JSON in the response at that point?

Have you used "raise ... from None" in #Python? If so, ...

2024-12-10T03:09:00Z

Have you used "raise ... from None" in #Python?

If so, what was your use case for "from None"?

What was the original exception that you were suppressing from the traceback and do you feel that suppression was helpful for users of your code (or were you just having fun with a new thing you learned)?

An assignment in Python points a variable to an object. Read more ...

2024-12-09T22:54:48Z

An assignment in Python points a variable to an object.

Read more 👉 https://trey.io/1m8zFT

#Python

There's one thing I've been REALLY enjoying using uv for: ...

2024-12-09T20:10:24Z

There's one thing I've been REALLY enjoying using uv for: writing standalone Python scripts that require third-party dependencies.

More on my current (somewhat conservative) uses for uv: https://treyhunner.com/2024/12/lazy-self-installing-python-scripts-with-uv/

#Python #uv

"But there's an even better way to check whether one ...

2024-12-09T14:45:32Z

"But there's an even better way to check whether one string is the substring of another string."

Read more 👉 https://trey.io/5gu5Fs

#python

glad you found it helpful!

2024-12-09T06:23:14Z

In reply to nevent1q…5cs2
_________________________

glad you found it helpful!

Every Wednesday morning, I share a Python tip via email. I've ...

2024-12-06T00:00:06Z

Every Wednesday morning, I share a Python tip via email. I've been doing this since June 1, 2022.

If you'd like to read a Python tip from me each week, you can subscribe at https://trey.io/news 🐍💌

#Python

Creating a singleton class by making a custom constructor does ...

2024-12-05T22:50:28Z

Creating a singleton class by making a custom constructor does work, but it might seem a little bit misleading to someone using this class.

Read more 👉 https://trey.io/RAvlR1

#Python

When debugging in #Python, I prefer this: >>> ...

2024-12-04T02:08:00Z

When debugging in #Python, I prefer this:

>>> vars(some_obj)

Over this:

>>> some_obj.__dict__

Why?

1. When possible, I prefer high-level operations over direct dunder access
2. It's 2 fewer characters!

And yes I also use dir(), but the two have slightly different uses and both can be handy!

More on dir & vars: https://pym.dev/inspecting-python-objects/

I really enjoyed his classes. I tried to configure my quarterly ...

2024-12-03T23:26:35Z

In reply to nevent1q…jvul
_________________________

I really enjoyed his classes. I tried to configure my quarterly schedule to increase my changes of taking various classes with him because I enjoyed his teaching style so much.

Just realized an odd coincidence from a 13-year-old open source ...

2024-12-03T19:45:25Z

Just realized an odd coincidence from a 13-year-old open source contribution.

I contributed the "ping" command to the WINE command prompt to make it simply sleep (DOS didn't have sleep so batch files often used ping to sleep).

This OSS contribution was part of a homework assignment.

I just realized today that my professor for that class (Dr. Paul Eggert) was one of the two authors of the GNU/Linux sleep utility (along with many other utilities he helped write). 🤯

#OpenSource

What's a fairly fundamental #Python feature that you're ...

2024-12-03T16:43:00Z

What's a fairly fundamental #Python feature that you're glad you've embraced?

Could be a feature that some other programming languages don't have or one whose purpose you didn't really understand when you first learned about it.

Recursion is most often useful when the problem you're ...

2024-12-03T07:17:15Z

Recursion is most often useful when the problem you're solving involves traversing or constructing a tree-like structure.

Read more 👉 https://trey.io/vIw7Up

#recursion #python

Need to remove duplicates from a list? >>> items = [2, ...

2024-12-03T03:09:00Z

Need to remove duplicates from a list?
>>> items = [2, 1, 6, 4, 2, 4, 7]

This works:
>>> dedup = set(items)

But item order will be lost:
>>> dedup
{1, 2, 4, 6, 7}

If the original order should be maintained, you can use the keys of a dictionary:
>>> dedup = list(dict.fromkeys(items))

Dictionary keys maintain their insertion order in #Python:
>>> dedup
[2, 1, 6, 4, 7]

More on that last approach: https://pym.dev/deduplicate-lists/#de-duplicating-without-losing-order

Last day to get Python Jumpstart for 50% off. 🐍 There's a ...

2024-12-02T19:21:00Z

Last day to get Python Jumpstart for 50% off. 🐍

There's a 30 day money-back guarantee, no questions asked. 💰

https://pym.dev/courses/jumpstart/overview

#Python #CyberMonday

If you're new to #Python and seeking a solid hands-on ...

2024-12-02T01:46:00Z

If you're new to #Python and seeking a solid hands-on introduction, keep in mind that tomorrow is the last day to save $100 on Python Jumpstart. ⏰

Money-back guarantee for 30 days, no questions asked. 💌

https://pym.dev/courses/jumpstart/overview

Learning Python is like learning the flute. 🪈 You won't ...

2024-11-30T19:21:01Z

Learning Python is like learning the flute. 🪈

You won't get far from just watching videos and reading. 📼

Practice should take up MOST of your learning time. 🧠

That's why my new #Python Jumpstart course is practice-centered. Each day, you'll watch a 4 minute video and then attempt to write Python code. ⌨

It's 2 hours of video, but about 20 hours of carefully crafted bite-sized exercises. 🍪

I just launched this course and it's 50% off, but only through Monday. 💸

https://pym.dev/courses/jumpstart/overview

Looking for Python-related Black Friday sales? 🐍🤑 I made a ...

2024-11-29T19:23:11Z

Looking for Python-related Black Friday sales? 🐍🤑

I made a list of all the sales I'm aware of.

https://treyhunner.com/2024/11/python-black-friday-and-cyber-monday-sales-2024/

Includes sales from me, Reuven M. Lerner (npub10qr…kh0f), Brian Okken (npub1j7s…hmke), Michael Kennedy (npub1mcu…7m70), Rodrigo 🐍🚀 (npub1c0x…ptl2), Mike Driscoll (npub1ht8…374v), Sundeep (npub12e8…p2qf), and many more Python content creators.

Let me know if you spot more sales that I missed.

#Python #BlackFriday

For Black Friday, why not buy yourself a bunch of Python skills? ...

2024-11-29T18:10:00Z

For Black Friday, why not buy yourself a bunch of Python skills?

You can't really do that, but you CAN buy yourself a commitment to learn Python.

My new Python Jumpstart course is 50% off today. 💸

https://pym.dev/courses/jumpstart/overview

#Python #BlackFriday

When the first line in a function is a string all on its own, ...

2024-11-28T02:06:21Z

When the first line in a function is a string all on its own, Python reads that string as documentation, and it stores that docstring on the function, so that tools like help can find it.

Read more 👉 https://trey.io/a5O8qe

#Python

What's in a name? That which we call a duck By any other name ...

2024-11-28T01:46:00Z

What's in a name? That which we call a duck
By any other name would quack the same;
So a sequence would, were it not a sequence call'd,
Retain that dear iterability which it bears
Without that title. Sequence, doff thy name,
And for that name which is no part of thee
give thy iterator to me.

#Python #DuckTyping

Most Intro to Python courses consist of 2 hours of lectures and ...

2024-11-27T16:08:00Z

Most Intro to Python courses consist of 2 hours of lectures and 2-10 exercises.

My new Python Jumpstart course is different.

It's dozens of very short videos, each followed by an exercise.

You'll watch/read something new for 4 minutes and immediately try it out yourself.

This new course is 50% off through Monday.

https://pym.dev/courses/jumpstart/overview

#Python

n >= k (where n is the size of the iterable and k is the ...

2024-11-27T06:09:40Z

In reply to nevent1q…09am
_________________________

n >= k (where n is the size of the iterable and k is the number of items you want) so n log n >= n log k, meaning sorting will be slower (especially if k is much smaller than n).

The number of items to retrieve. 3 in this case.

2024-11-27T05:03:18Z

In reply to nevent1q…jym8
_________________________

The number of items to retrieve. 3 in this case.

Avoid unnecessary sorting in Python. ❌ Instead of this: ...

2024-11-27T02:08:00Z

Avoid unnecessary sorting in Python.

❌ Instead of this:
smallest = sorted(items)[0]

✅ Do this:
smallest = min(items)

❌ Instead of this:
smallest = sorted(items)[:3]

✅ Do this:
import heapq
smallest = heapq.nsmallest(3, items)

Why avoid sorting?

1. Performance: min is O(n), nsmallest is O(n log k), sorted is O(n log n)
2. Readability: min & nsmallest note what we really want our code to do

For more on the performance of various operations in #Python, see https://pym.dev/time-complexities/

Data structures don't contain objects, they contain pointers ...

2024-11-27T00:44:23Z

Data structures don't contain objects, they contain pointers to objects.

Read the full article: Data structures contain pointers
▸ https://trey.io/uvntzs

#Python

With Python Jumpstart, there are no 10-20 minute lectures in ...

2024-11-26T16:43:01Z

In reply to nevent1q…6nz2
_________________________

With Python Jumpstart, there are no 10-20 minute lectures in Jumpstart. Just 4 minutes on a new topic and then 30 minutes trying it yourself. (You'll repeat that process many times 🔁)

My new Python Jumpstart course is 50% off through Monday. 💸

Ready to jumpstart your learning? 🎓

https://pym.dev/courses/jumpstart/overview/

Trouble learning Python? 🐍 You need active recall and spaced ...

2024-11-26T16:43:00Z

Trouble learning Python? 🐍

You need active recall and spaced repetition. 🧠

In other words, attempt to write code yourself to apply each new concept you visit and do this repeatedly over many days.

Most Intro to Python courses consist of a series of lectures. 📺

Good lectures can be a lot of fun, but they do very little to help making learning stick.

That's why my new Python Jumpstart course is 90% exercise-driven.

#Python

parent doesn't work well for non-absolute paths. ...

2024-11-26T06:36:15Z

In reply to nevent1q…ejxy
_________________________

parent doesn't work well for non-absolute paths. Path('.').parent returns Path('.')

In Python, instead of this: BASE_DIR = ...

2024-11-26T03:09:00Z

In Python, instead of this:

BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))

I prefer this:

BASE_DIR = pathlib.Path(__file__).resolve().parent.parent

For more on the magic of Python's pathlib module, check out the article I published last week: https://pym.dev/pathlib-module

#Python #pathlib

Python's list comprehensions and if-else Read more 👉 ...

2024-11-25T20:13:21Z

Python's list comprehensions and if-else

Read more 👉 https://trey.io/djaxuq

#Python

Folks have been asking me for YEARS whether I have a self-paced ...

2024-11-25T19:12:42Z

Folks have been asking me for YEARS whether I have a self-paced Intro to Python course.

I'm finally launching one! It's called Python Jumpstart. 🎉

For this first launch week, it's 50% off.

Jumpstart your Python journey.
https://pym.dev/courses/jumpstart/overview/

#Python

Anyone done any work with the #Signal protocol? If you're up ...

2024-11-22T19:02:10Z

Anyone done any work with the #Signal protocol?

If you're up for answering questions from a friend who is building a Signal app for a good cause, please reply.

Thanks!

The first time folks use the re module in #Python, they often ...

2024-11-22T18:10:01Z

The first time folks use the re module in #Python, they often reach for re.match().

I usually recommend against using re.match().

Why?

Because re.match() matches from the beginning of the string, but does not match until the end of the string. Many find this behavior unexpected.

re.match(r"...") is equivalent to re.‍search(r"^...").

re.fullmatch(r"...") is equivalent to re.‍search(r"^...$").

I usually recommend reaching for re.‍search().

There's only ever one None value in memory within each Python ...

2024-11-22T08:26:41Z

There's only ever one None value in memory within each Python process.

Read more 👉 https://trey.io/8slkex

#Python

nice!

2024-11-22T01:07:47Z

In reply to nevent1q…2wra
_________________________

nice!

For the past 7 years, I've posted a summary of ...

2024-11-21T19:21:00Z

For the past 7 years, I've posted a summary of #Python-related Black Friday & Cyber Monday sales.

I'm posting extra early this year. I'll be updating as more sales are announced over the next week. Let me know if you hear of any I should add!

https://treyhunner.com/2024/11/python-black-friday-and-cyber-monday-sales-2024/

Comprehensions have their own scope: >>> n = 4 ...

2024-11-21T01:46:02Z

Comprehensions have their own scope:

>>> n = 4
>>> squares = [n**2 for n in range(9)]
>>> n
4

But loops do NOT have their own scope:

>>> n = 4
>>> for n in squares: ...
>>> n
81

This may seem like a gotcha, but there's a good reason for this.

For convenience, Python lacks variable declarations. Assignments "declare" implicitly. Due to this, function-level scope makes a LOT more sense in Python, so #Python's scope is function-level, not block-level.

https://trey.io/function-scope-oddity

#PythonOddity

Fixed. Thanks for noting that!

2024-11-20T03:07:03Z

In reply to nevent1q…ladv
_________________________

Fixed. Thanks for noting that!

I've updated my new pathlib article with additional examples, ...

2024-11-20T02:08:00Z

I've updated my new pathlib article with additional examples, improved wording, and more links to documentation. ✨

One nice thing about finally publishing in text form: folks happily provide (frequently) constructive feedback so I can immediately iterate. 💗

https://pym.dev/pathlib-module/

#Python #pathlib

I've been enjoying "uv tool" as a pipx replacement, ...

2024-11-19T16:43:00Z

I've been enjoying "uv tool" as a pipx replacement, but I hadn't looked into uvx.

💡 uvx is a way to play with a #Python CLI tool without installing it.

$ uvx --from strptime-cli strptime

$ uvx --from dramatic python -m dramatic

$ uvx names

Or jump into a virtual environment with a package pre-installed:

$ uvx --from requests python -q
>>> import requests

Context managers do sandwich our block of code between two steps, ...

2024-11-18T22:23:15Z

Context managers do sandwich our block of code between two steps, but they also ensure that the exit step is performed regardless of whether an exception occurred.

Read more 👉 https://trey.io/meA1Mx

#Python

I've finally written a pathlib cheat sheet & sales pitch ...

2024-11-18T16:44:01Z

I've finally written a pathlib cheat sheet & sales pitch combination post. ✨

Another many-year-old to-do list item done. ✅

If you've been looking for a post to link your pathlib-curious/confused coworkers to, I'm hoping this will help. 🔗

https://pym.dev/pathlib-module/

#Python #pathlib

I do not remember this but I'm curious 🤨

2024-11-18T05:14:42Z

In reply to nevent1q…zsvh
_________________________

I do not remember this but I'm curious 🤨

PEP idea from April 1 💡 Support for importing EVERYTHING: from ...

2024-11-18T04:39:17Z

PEP idea from April 1 💡

Support for importing EVERYTHING:

from * import *

#Python

When I find myself wondering what a specific #Python object is ...

2024-11-15T18:10:00Z

When I find myself wondering what a specific #Python object is all about, there are 4 functions I reach for:

1. type
2. help
3. dir
4. vars

More on inspecting Python objects: https://pym.dev/inspecting-python-objects/

Today I completed my annual ritual of checking whether I've ...

2024-11-14T22:25:12Z

Today I completed my annual ritual of checking whether I've created my PyCon account yet with any of the emails that exist in my password manager from past PyCon years. 😅

I could probably train my password manager to understand the year after the domain... but then I would lose this unusual ritual. 😆

"Mutation changes an object, which any number of variables ...

2024-11-14T22:23:14Z

"Mutation changes an object, which any number of variables may be pointing to."

Read more 👉 https://trey.io/h6y0n9

#Python

Trying to decide which tutorial ideas to submit to #PyConUS 2025. ...

2024-11-13T23:31:37Z

Trying to decide which tutorial ideas to submit to #PyConUS 2025.

Which of these 3 hour #Python tutorials would you want to work through at PyCon?

Our brains have at least two modes: one where we're focused ...

2024-11-13T14:50:35Z

Our brains have at least two modes: one where we're focused deeply on a problem and one where our mind is wandering.

Read more 👉 https://trey.io/rQVM9y

#CodingChallenge #Python

🤔 I'm curious to see examples of what you're imagining

2024-11-13T02:41:28Z

In reply to nevent1q…nnq6
_________________________

🤔 I'm curious to see examples of what you're imagining

I added support for many more formats to https://pym.dev/strptime ...

2024-11-13T02:08:01Z

I added support for many more formats to https://pym.dev/strptime and released a command-line version.

$ pipx install strptime-cli
$ strptime "Tue, 12 Nov 2024 09:50:24"
%a, %d %b %Y %H:%M:%S

The next time you run across a date/time string you need to parse in #Python, try it out!

I brought this issue up on the forum and am now even more ...

2024-11-12T22:24:23Z

In reply to nevent1q…67ya
_________________________

I brought this issue up on the forum and am now even more uncertain about which to recommend when.

https://discuss.python.org/t/clarify-usage-of-platform-system/70900

This ☝ The built-in exceptions are good enough in most cases. ...

2024-11-12T15:19:02Z

In reply to nevent1q…thud
_________________________

This ☝

The built-in exceptions are good enough in most cases.

If distinguishing between a KeyError and a MyLibraryKeyError is useful then make MyLibraryKeyError that inherits from KeyError.

If that's not useful today, but might be in the future then use KeyError now and you can always inherit from KeyError in that eventual future that might come one day.

We often rely on the falsiness of None in Python. Read more 👉 ...

2024-11-12T04:48:20Z

We often rely on the falsiness of None in Python.

Read more 👉 https://trey.io/dAEgtL

#Python

I've been preferring platform.system() as well, but I suspect ...

2024-11-12T03:07:45Z

In reply to nevent1q…ns4w
_________________________

I've been preferring platform.system() as well, but I suspect that may be the wrong approach, as the docs say that platform.system() returns a user-facing OS name, which implies that the string isn't necessarily meant to be machine-readable.

I link to the same SO question. I don't find the argument ...

2024-11-11T22:54:25Z

In reply to nevent1q…3acu
_________________________

I link to the same SO question. I don't find the argument against sys.platform, especially given that the docs show a table of known values while the platform.system docs are much less complete.

This could be a documentation issue, but when docs are lacking I tend to assume a tool might not be as officially sanctioned as I might otherwise assume.