fidzu : python

Who runs for the PSF Board? People who care about the Python community, who want to see it flourish and grow, and also have a few hours a month to attend regular meetings, serve on committees, participate in conversations, and promote the Python community. We're looking for candidates with a diverse range of skills and backgrounds, including leadership experience, fundraising knowledge, non-profit familiarity, and event organizing. Technical expertise, a record of collaboration, and experience speaking or teaching in the Python community are also all qualities we hope to see in Board members.

Want to learn more about being on the PSF Board? Check out the following resources to learn more about the PSF, as well as what being a part of the PSF Board entails:

• Life as Python Software Foundation Director video on YouTube
• FAQs About the PSF Board video on YouTube
• Our past few Annual Impact Reports:
• • 2024 Annual Impact Report
  • 2023 Annual Impact Report
  • 2022 Annual Impact Report

Board Election Timeline

• Nominations open: Tuesday, July 28th, 2:00 pm UTC
• Nomination cut-off: Tuesday, August 11th, 2:00 pm UTC
• Announce candidates: Thursday, August 13th
• Voter affirmation cut-off: Tuesday, August 25th, 2:00 pm UTC
• Voting start date: Tuesday, September 1st, 2:00 pm UTC
• Voting end date: Tuesday, September 15th, 2:00 pm UTC

Not sure what UTC is for you locally? Check this UTC time converter!

Nominations

You can nominate yourself or someone else. If you're nominating someone else, we'd encourage you to reach out to them first to make sure they're excited about the opportunity and give them a heads up that they'll need to submit their own nomination statement via the nomination form. Take a look at last year's nomination statements for reference.

To submit a nomination for yourself or someone else, use the 2026 PSF Board Election Nomination Form on our website. The form will open on Tuesday, July 28th, 2:00 pm UTC and close on Tuesday, August 11th, 2:00 pm UTC.

To support potential candidates and nominators, the PSF has created a nomination resource (embedded below). It includes tips, formatting instructions, and guidance on what to include in a nomination. The goal is to help nominees understand what to expect and ensure that all candidates are provided the same clear and consistent standards.

Nominee Election Participation

PSF Board nominees will be invited to participate in the PSF Board Office Hour on the PSF Discord on September 8th at 1PM UTC. PSF Board Office Hours are a chance for the Python community to ask questions, share perspectives, and in this case, connect with PSF Board nominees. If you are unable to attend the sessions for whatever reason, that's totally fine, though we'd love to have each of you participate!

PSF Board nominees will also be invited to participate in text-based interviews that will result in content published on the PSF Blog. The interview questions will be similar to those used in the video interviews that have been produced in years past:

• 2025
• 2024
• 2023

A current PSF Board member will reach out to you with instructions and field any questions you may have about the interviews. We ask that nominees keep an eye on their email inboxes during the nomination period and right after so that we can ensure your interview responses get published for the Python community's consideration.

Voting Affirmation Reminder

Every PSF Voting Member (Supporting, Contributing, and Fellow) must affirm their intention to vote no later than Tuesday, August 25th, 2:00 pm UTC, to participate in this year's election. You should have received an email from "psf@psfmember.org <Python Software Foundation>" with the subject "[Action Required] Affirm your PSF Membership voting intention for 2026 PSF Board Election" that contains information on how to affirm your voting status.

You can see your membership record and status on your PSF Member User Information page. If you are a voting-eligible member and do not already have a login, please create an account on psfmember.org first and then email psf-elections@pyfound.org so we can link your membership to your account.

23 Jul 2026 8:06am GMT

Django 6.1 release candidate 1 is now available. It represents the final opportunity for you to try out the version that offers a harmonious mélange of new features and usability improvements, before Django 6.1 final is released.

The release candidate stage marks the string freeze and the call for translators to submit translations. Provided no major bugs are discovered that can't be solved in the next two weeks, Django 6.1 will be released on or around August 5. Any delays will be communicated on the Django forum.

Please use this opportunity to help find and fix bugs (which should be reported to the issue tracker), you can grab a copy of the release candidate package from our downloads page or on PyPI.

The PGP key ID used for this release is Jacob Walls: 131403F4D16D8DC7

22 Jul 2026 8:00pm GMT

Starting Tuesday 28 July, 2026, the PSF Diversity & Inclusion (D&I) Workgroup is opening its virtual doors once a month on Discord. Come chat with workgroup members from all over the world!

Doing diversity and inclusion work in tech can feel isolating sometimes. You might be organizing a meetup, writing a code of conduct, trying to get funding for your community, or helping people feel welcome, often in your spare time, and wondering if anyone else is wrestling with the same things.

They are. We are! And we would love to get all of us in the same room.

This July, the PSF D&I Workgroup will be hosting monthly office hours within Discord. These will be open, text-based conversations where we encourage you to ask questions, sha
re what you are working on, and connect with other people who care about making the Python community more welcoming.

The details

The PSF D&I Office Hours will be on the last Tuesday of every month. Because our community is spread across the globe, we will alternate between two times so we can cover as many time zones as possible:

• 1 PM UTC / 9 AM US Eastern

• 9 PM UTC / 5 PM US Eastern

Our first session will be on Tuesday, 28 July 2026 at 1 PM UTC. Here is roughly what that looks like around the world:

If 6 AM in Los Angeles or 11 PM in Sydney made you wince, do not worry. The August session will be at 9 PM UTC, and we will keep alternating from there.

You will find us in the #psf-diversity channel on the PSF Discord. If you're new to Discord, check out some Discord Basics to help you get started.

What will we talk about

Honestly? Whatever is on your mind related to Python, your communities, and D&I.

Since our workgroup exists to advise the PSF on diversity and inclusion, some conversations we are especially hoping to have include:

• Ideas for policies, initiatives, and grant proposals to diversify the PSF missions. Feedback from the community about these topics will help the PSF D&I Workgroup provide recommendations to the PSF Board of Directors.

• Your feedback, plain and simple. We want to understand how the PSF can better serve and grow a diverse membership, and we cannot do that without hearing from the community itself.

• How things are actually going. Part of our job is measuring and sharing the PSF's progress on its diversity initiatives, and we would rather do that in conversation with you than in a report nobody reads. We also want to understand and learn about the current state of Python communities around the world.

No camera, no mic, no pressure

Office hours are text chat only.

Show up in your pajamas, join from the bus, lurk quietly for the first twenty minutes. It is all fine.

And if you cannot make it at all, the conversation stays in the channel, so you can catch up later when it suits you. If something in the chat sparks a thought you would like to share with us directly, you are always welcome to email the workgroup at diversity-inclusion-wg@python.org.

Bring your own language

Because we are the D&I Workgroup, our members come from around the world! Alongside the main conversation, we will open threads in other languages where possible. Depending on the presence of our members, we would be happy to chat in Spanish, Portuguese, Chinese, Hindi, French or even Persian! Let us know during the office hour if you have a specific language you hope to converse in, or jump in with whichever language thread feels like home.

See you on the 28th!

The first office hour session is on Tuesday, 28 July 2026 at 1 PM UTC, in #psf-diversity on Discord.

Come say hi, even if it is just to tell us what you are working on with Python. We are really looking forward to meeting you!

22 Jul 2026 9:46am GMT

bliptracker was a side project that I happened to produce during June and last week realised I hadn't written about it here, so here goes!

One annoyance I have with Claude.ai (or other web based LLM interfaces), is that I would start multiple conversations across multiple topics such as client work, organising my Todoist, an idea to explore, gifts to research, the list goes on, but I was keeping open tabs for each conversation to not lose track of the active conversations, but this didn't work as I still had those open loops in my head to follow up to move each conversation forwards.

I didn't want a full blown task manager (I pay for Todoist which fits perfectly), but I did want to track the state of each conversation in Claude from both the web app and the mobile. The result is a two fold solution, first there is a system prompt telling Claude to end each respond with either a 🔴, along with the next action required from me, or a ✅ which tells me the conversation is resolved. The second part of the solution is a Chrome extension which then automatically updates the title of any conversation with the red dot or green check mark, so I can tell at a glance which chats need work and which are done.

I do have a couple more features planned such as supporting other LLMs and a possible snooze feature. But for now it's a small working project that keeps my chats organised. It's available at bliptracker.xyz.

One final point on this project, I hope that eventually it gets replace by Anthropic building a better native product for tracking the status of chats, it's very limited right now. More widely this highlights that while new models are powerful and can do more, it still requires us as engineers to build products that solve actual problems in novel, tasteful and well designed solutions. That is what we pay for when buy a tool and what our users expect from us and something that no model as far as I can see will ever replace.

22 Jul 2026 5:00am GMT

I recently migrated one of my client projects from the legacy django-csp package to Django 6.0's built-in Content Security Policy (CSP) support (release note). This security header is a powerful tool for preventing unwanted content from being loaded on your site, so configuration correctness is paramount. The migration was fairly straightforward, but a few pages had complicated overrides, so I wanted to be sure that no CSP headers had been changed by my swapping of CSP implementations.

I had the idea to verify no page had changed its content-security-policy header by crawling the site with Django's test client, outputting URL and header contents during the process. By diffing the output from crawls before and after the migration, I could check for changes and track down which pages had been affected.

The core loop of that script looked something like this:

from collections import deque
from django.test import Client


client = Client()
client.force_login(superuser)

queue: deque[str] = deque(["/", "/admin/"])
...

while queue:
    url = queue.popleft()
    ...
    response = client.get(url, follow=False)
    ...
    print(f"{url}\t{response.headers.get('content-security-policy')}")
    ...
    for anchor in BeautifulSoup(response.content, "html.parser").find_all(
        "a", href=True
    ):
        # Enqueue these found links
        ...

This simple crawl of the site ended up flushing out seven non-CSP bugs, despite the project having 100% test coverage and a full suite of integration tests. Those bugs were due to incorrect link generation, admin features not being disabled, and regular old broken code.

I was pretty impressed with the power of this technique for finding broken stuff! Given this experience, I wanted to expand the script into a reusable tool, which I have now done with django-crawl.

To use django-crawl, install it, add it to INSTALLED_APPS, and you can run the crawl management command:

$ ./manage.py crawl -v 2
🐛 Crawling up to 1000 URLs, logged in as Ad Min
/
/about/
/blog/
/contact/
/dev/
/blog/2026/
/blog/2025/
/blog/2026/07/22/introducing-django-crawl/
...
🦋 Crawled 1000 URLs, encountered 0 errors, stopped due to reaching max URL limit of 1000.

The command reports any errors it encounters, from broken links to exceptions. The output uses Rich for pretty formatting and a live spinner while it runs. Adding -v 2 prints the URLs as they are crawled.

The crawler discovers links in various forms in HTML responses (<a href>, <link href>, <script src>, <img src>, etc.), sitemaps, and feeds. If you have a sitemap, you can start your crawl with a simple:

$ ./manage.py crawl /sitemap.xml

The HTML parsing is done with a custom Rust extension built with html5ever, the HTML parser from the Servo project, so it's very fast. And with no overhead from real HTTP requests or inter-process communication, the crawl is limited only by how fast your application code can run.

django-crawl also provides a Python API that you can use to make a mega-test that crawls your whole site with example data, raising an ExceptionGroup if any errors are encountered:

from django.contrib.auth.models import User
from django.test import TestCase

import django_crawl


class CrawlTests(TestCase):
    @classmethod
    def setUpTestData(cls):
        cls.admin = User.objects.create_superuser(username="admin")

    def test_crawl(self):
        client = django_crawl.CrawlClient()
        client.force_login(self.admin)
        django_crawl.crawl("/", "/admin/", client=client)

I am not sure if this is a good fit for most projects, since it will leave you with one long test that exercises many views. But it might be good for building a "safety net" on untested projects, something I know Jeff Triplett likes to do (ref Django Chat #24).

22 Jul 2026 4:00am GMT

Seven days of sponsor booth, talks, sprints, and hallway chats.

21 Jul 2026 11:56am GMT

As I have discussed in previous posts, "AIs" can make mistakes. In fact, they do make mistakes, and their mistake-making patterns are such that where and how they will make mistakes is both uncertain and constantly changing.

Thus, in any scenario where you want to attempt to make "productive" use of "AI", you must have a system in place for checking every result. Not checking some results; checking every result. If each result might have a consequence for you (and if it didn't have a consequence, why bother automating it?) and you cannot predict in advance which kinds of results will need verification, then verification is always required.

The verification often ends up being just as expensive as doing the work in the first place, which means that if you want your usage of "AI" to be personally profitable, you have to find someone else to externalize the cost of verification onto. This person becomes your adversary, and, if you are successful, your "AI's" victim.

The Ladder-Climber And Their Reverse-Centaur Rungs

One way that this constellation of facts can straightforwardly assemble themselves into a dystopian nightmare is the phenomenon, described by Cory Doctorow, of the reverse centaur. This is when your employer non-consensually turns you into the verification system. The "AI" does the fun part of initially performing the work, and then you do the boring part where you check if the robot is right and clean up its messes, even if everyone already knows that it would, in aggregate, be cheaper for you to do the work in the first place.

Reverse centaurs can be made from any automation, not only "AI" automation. I think that there is a reason that this term happens to have emerged in the "age of AI", though, and not with earlier automation technologies (even those which were considerably more viscerally horrific). That reason is: the wrongness of "AI" output is not merely a technical feature that must be compensated for, it is a generalized externality.

As I mentioned above, if you are responsible for the entirety of the work, both extruding the "AI" output and checking it, it's usually cheaper to have humans do the entirety of the work to begin with. When humans do the writing directly, we can check as we go, and thus verification doesn't need to be as comprehensive.

When "AI" coding advocates say "code review is the bottleneck", what they are observing is that the LLM is still rolling the dice for each PR, and a human is still necessary to verify that each of those rolls is a winner. But calling this process "code review" is a bit of a misnomer; it's not really "code review" in the traditional sense, it's human understanding.

Before the advent of "AI", the human understanding was implicit in the process of writing the code in the first place¹, and the code review was a way of diffusing and extending that understanding. Now that the code can be authored with no initial understanding taking place, that cost has not gone away, it has moved.

Human understanding was always the bottleneck.

However, this is taking a collaborative view of a software project, where satisfying the needs and solving the problems of your customers are the goals. We can see that "AI" is a bad tool to satisfy those goals, because all it's doing is converting the first half of the work, that of understanding the code as you write it, to understanding the agent's output as you read it.

What if, instead, we were to take the view that every software company is a Hobbesian nightmare, red in tooth and claw? In this view, the only goal of a software project is for the individual developers to make their promo cycles and get their bonuses. Given that there is only a certain amount of money to go around, this is a zero-sum game where each programmer wants to look more productive than their colleagues.

Pretty much every organization finds it easy to reward "productivity" as expressed by lines of code emitted, but the benefits of doing thorough and thoughtful design, analysis, and code review very difficult to reward. In this world, an LLM is an invaluable tool for the sociopathic ladder-climber, particularly if your legacy organization is still structuring their workflows as if the person prompting the bot is "writing" the code, and then they get to foist off the act of "reviewing" the code onto someone else.

Here, the prompter effectively externalizes the cost of the LLM's failures but internalizes any benefits. The prompter will vibe-code a big feature, so large that the assigned reviewer can't possibly comprehend it all effectively. When this happens, the reviewer will, eventually, be pressured to approve it, even if they can try to spot a few problems along the way. The reviewer has their own work to get back to, after all, the obligation to review the prompter's (read: the bot's) code is a drain on their time that they are not going to get rewarded for.

If this feature is a big success, the prompter gets a promotion. If it causes a big issue, well, the reviewer must not have been careful enough.

This is why LLMs are "good for coding", and also why their biggest promoters keep having outages.

The Generative Gish Galloper

Coding is the biggest "success story" of this type of adversarial communication, but it is by far not the only instance of such a thing. LLMs create a new form of leverage that can turn Brandolini's law from a linear advantage into an exponential one. If you are engaged in a political debate where you want to overwhelm the other side in nonsense, an LLM can generate bullshit faster than it is physically possible for a human being to type, let alone respond thoughtfully. There is an asymmetry to the utility of this weapon as well: only one side of the political spectrum wants to flood the zone and destroy trust in institutions and the concept of truth. There's a good reason that the fascists love it.

Straightforward Spam and Fraud

This is kind of obvious, but LLMs can generate lightly-customized, plausible-looking text much more quickly than any human being. This facilitates their use in fraud, spam, and scams. In a spamming or fraudulent interaction, once again, the costs are externalized onto the victim: the recipient of a spam message has to do all the work of "checking" the LLM's output. Spammers already expect very low hit rates from boilerplate, and if the LLM can increase those percentages from 1% to 5% the technology will pay for itself; they don't need anything like reliable accuracy.

Customer "Support"

If you have any kind of commercial relationship with a company, I probably don't even need to mention this: customer "support" bots are a misery. Everybody knows it at this point. But customer support is usually conceptualized by businesses as an adversarial interaction, because it is a cost center. They maintain internal metrics on time-to-resolution and try to optimize them. Implicitly, this creates a dynamic where the goal of the customer service agent's job is not to solve your problem, but to emit noise that will cause you to think your problem is resolved, or to give up, as fast as possible. Unsurprisingly, LLMs can emit this noise faster than humans can, getting those customers off the phone. But those customers will remember those interactions, and the story outside the TTR metrics is horrible.

Similarly to the situation in software development, LLMs can look very good on paper for customer support, but mostly what they are doing is illuminating the problems with the industry's existing metrics, by turning "winning the metrics battle against the customer" into a more obvious and immediate defeat for the company's long term reputation.

"Education"

In 2026 it is sadly a fact of life that students cheat all the time using "AI", and that this cheating is very successful, in that the teachers find it very hard to detect.

LLMs are great for cheating on schoolwork because the student is externalizing the work of the checking onto the teachers, who are often starting at a disadvantage to begin with, at least in the US.

My view is that this is happening because of a divergence in the way that students vs. teachers (or, more accurately, "the broader educational system") view grading.

When a student is asked to write an essay, the teachers see the effort as both intrinsically worthwhile for the student, as well as useful as a pedagogical tool to evaluate and react to the student's progress. The student, by contrast, sees a stumbling block designed to knock them off the path to success and into a permanent underclass. It is no wonder that the student sees "AI" as useful to their own goals and has no compunction about deploying it.

There is a bitter irony that the ability to understand the inherent value of actually writing the essay on their own is the sort of thing that students can really only learn by writing a bunch of essays. There's no way that I can think of which makes the benefit legible as long as a shortcut is available.

The net effect here is a downward spiral, where the already-wobbling educational system is sustaining an attack that it doesn't have the resources to recover from. The individual students' attacks against their teachers and their schools' grading systems might appear to momentarily succeed, but they will win the battle and lose the war.

Spamming "For Good"?

Usually when we talk about someone unilaterally choosing to enter into an adversarial relationship, that's an "attack" and for good reasons we have a negative impression of the attacker. However, I would be remiss if I did not point out that there are some cases where the relationship was already adversarial; just because you're the attacker doesn't mean that you are evil.

For example we might imagine use-cases like automatically filing appeals for prior authorizations against health insurance. It's relatively well-known at this point that the main way for-profit insurers maintain their margins is by denying claims right up to the line of the policies themselves being fraud, so using a spamming tool to fight them might be entirely justifiable² in that case.

Similarly, using an LLM could be justified in a fight against a company refusing to honor a warranty. One could imagine using an LLM to immediately generate replies and escalations.

However, even in imagined cases like these, the underlying problem is that the insurers and the vendors already have a tremendous amount of structural power, so it is more likely that they will have the advantage in deploying a communications weapon like an LLM, as well as enacting policies to simply ignore any LLM-based communication that you might submit. Worse, if these strategies were to become widespread, they might provide an excuse to reject any communications by feeding them into an unreliable "LLM detector" and issuing an automated "computer says no" even to hand-written correspondence.

It is also worth stressing that these cases are imagined, as compared to the very real coworker-abuse, spam, scam, fraud, and disinformation campaigns being waged in real life today.

Therefore, while legitimate uses might exist, it's hard to imagine that there's anywhere they would be genuinely valuable and sustainable. In the best case "AI" will provide a temporary advantage for underdogs that will provoke an arms race which the resource-advantaged adversaries will win in the long run, in the worst case the arms race itself will cement permanent structural change that will make things worse.

"Search" By Stealing

Most of the adversarial utility of "AI" is on the "write" side, since write-amplification is more obviously aggressive than reading. But the "read" side of LLMs - summarization and question-answering - can be a form of attack as well.

To begin with, the act of reading itself is currently enormously destructive, but that's arguably not a fundamental aspect of this technology. They could set reasonable rate-limits and respect things like robots.txt, as search engines have for decades now. They could also refrain from committing criminal levels of copyright infringement. But, today, using "AI" tools does suborn this sort of out-of-control crawling.

More insidiously, consider the scenario described in this YouTube video. The LTT Bros decided to try Linux again, and in the course of so doing, they had problems. When trying to solve these problems, they were faced with a choice: they could consult Reddit, or they could ask an LLM. Asking an LLM would "gaslight the heck out of" them, but they still found it preferable, because they would at least get an answer without getting yelled at.

Initially this sounds great. But it also means that you want to extract knowledge from a community, while mechanically eliding any values or norms that the community may want to impart as part of offering that knowledge. As someone who spent many years in a community tech support role, this is worrying. Many requests for support are people asking how to do things that will momentarily solve a superficial problem but create a long-term reliability problem or even an immediate security risk, that the question-asker doesn't want to hear about. Consider the question "I'm tired of entering my password so much, how do I make it so my laptop unlocks automatically". An obsequious chatbot will helpfully tell you how to do this without pushback.

But, this is also a sort of ethically murky area. The Linux community is somewhat famously, for many years now, a toxic cesspool of general hostility, misogyny, etc. It is certainly a good thing that people can get access to this knowledge without subjecting themselves to abuse. But it also means that the people with the power and the privilege to change the community for the better can just quietly withdraw, rather than fixing the problems. It also means that the positive elements of culture cannot be transmitted, and people will have no opportunity to learn about unknown unknowns.

In this case, the "adversarial" communication is with society. The thing that using an LLM for search lets you do is withdraw from society and avoid forming any personal connections. There are some personal connections which are painful and annoying, and so that can feel like a momentary balm. But the need to make connections in general is, like, the concept of society itself.

Who Am I Hurting?

LLMs are good at adversarial communication. They are so good at it, relative to their other benefits, that they will tend to make communications adversarial if you are not remaining vigilant about the possibility that it might do so. My request to you, dear reader, if you are going to use such tools, is to always ask yourself, "who might I be hurting, if I use an LLM for this?"

If you're using an "AI", who is its adversary? If you haven't given it one yet, who might the "AI" turn into an adversary? Who might you overwhelm with an asymmetric amount of output, or, if you're receiving information and not sending it, who are you taking that information from without consulting?

Figure out the answers to these questions and conduct yourself accordingly; the answer might be "yourself".

Acknowledgments

Thank you to my patrons who are supporting my writing on this blog. If you like what you've read here and you'd like to read more of it, or you'd like to support my various open-source endeavors, you can support my work as a sponsor!

23 Jun 2026 8:06pm GMT

Codecov's unreliability breaking CI on my open source projects has been a constant source of frustration for me for years. I have found a way to enforce coverage over a whole GitHub Actions build matrix that doesn't rely on third-party services.

09 Jun 2026 12:00am GMT

Let's say you're writing a Python library.

In this library, you have some collection of state that represents "options" or "configuration" for a bunch of operations. Such a set of options is a bundle of potentially ever-increasing complexity. Thus, you will want it to have an extremely minimal compatibility surface, with a very carefully chosen public interface, that is either small, or perhaps nothing at all. Such an object conveys state and might have some private behavior, but all you want consumers to be able to do is build it in very constrained, specific ways, and then pass it along as a parameter to your own APIs.

By way of example, imagine that you're wrapping a library that handles shipping physical packages.

There are a zillion ways to do it ship a package. There are different carriers who can ship it for you. There's air freight, and ground freight, and sea freight. There's overnight shipping. There's the option to require a signature. There's package tracking and certified mail. Suffice it to say, lots of stuff.

If you are starting out to implement such a library, you might need an object called something like ShippingOptions that encapsulates some of this. At the core of your library you might have a function like this:

1
2
3
4
5

async def shipPackage(
        how: ShippingOptions,
        where: Address,
    ) -> ShippingStatus:
    ...

If you are starting out implementing such a library, you know that you're going to get the initial implementation of ShippingOptions wrong; or, at the very least, if not "wrong", then "incomplete". You should not want to commit to an expansive public API with a ton of different attributes until you really understand the problem domain pretty well.

Yet, ShippingOptions is absolutely vital to the rest of your library. You'll need to construct it and pass it to various methods like estimateShippingCost and shipPackage. So you're not going to want a ton of complexity and churn as you evolve it to be more complex.

Worse yet, this object has to hold a ton of state. It's got attributes, maybe even quite complex internal attributes that relate to different shipping services.

Right now, today, you need to add something so you can have "no rush", "standard" and "expedited" options. You can't just put off implementing that indefinitely until you can come up with the perfect shape. What to do?

The tool you want here is the opaque data type design pattern. C is lousy with such things (FILE, pthread_*_t, fd_set, etc). A typedef in a header file can easily achieve this.

But in Python, if you expose a dataclass - or any class, really - even if you keep all your fields private, the constructor is still, inherently, public. You can make it raise an exception or something, but your type checker still won't help your users; it'll still look like it's a normal class.

Luckily, Python typing provides a tool for this: typing.NewType.

Let's review our requirements:

1. We need a type that our client code can use in its type annotations; it needs to be public.
2. They need to be able to consruct it somehow, even if they shouldn't be able to see its attributes or its internal constructor arguments.
3. To express high-level things (like "ship fast") that should stay supported as we add more nuanced and complex configurations in the future (like "ship with the fastest possible option provided by the lowest-cost carrier that supports signature verification").

In order to solve these problems respectively, we will use:

1. a public NewType, which gives us our public name...
2. which wraps a private class with entirely private attributes, to give us an actual data structure, while not exposing the constructor,
3. a set of public constructor functions, which returns our NewType.

When we put that all together, it looks like this:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17

from dataclasses import dataclass
from typing import Literal, NewType

@dataclass
class _RealShipOpts:
    _speed: Literal["fast", "normal", "slow"]

ShippingOptions = NewType("ShippingOptions", _RealShipOpts)

def shipFast() -> ShippingOptions:
    return ShippingOptions(_RealShipOpts("fast"))

def shipNormal() -> ShippingOptions:
    return ShippingOptions(_RealShipOpts("normal"))

def shipSlow() -> ShippingOptions:
    return ShippingOptions(_RealShipOpts("slow"))

As a snapshot in time, this is not all that interesting; we could have just exposed _RealShipOpts as a public class and saved ourselves some time. The fact that this exposes a constructor that takes a string is not a big deal for the present moment. For an initial quick and dirty implementation, we can just do checks like if options._speed == "fast" in our shipping and estimation code.

However, the main thing we are doing here is preserving our flexibility to evolve the related APIs into the future, so let's see how we might do that. For example, let's allow the shipping options to contain a concrete and specific carrier and freight method:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35

from dataclasses import dataclass
from enum import Enum, auto
from typing import NewType

class Carrier(Enum):
    FedEx = auto()
    USPS = auto()
    DHL = auto()
    UPS = auto()

class Conveyance(Enum):
    air = auto()
    truck = auto()
    train = auto()

@dataclass
class _RealShipOpts:
    _carrier: Carrier
    _freight: Conveyance

ShippingOptions = NewType("ShippingOptions", _RealShipOpts)

def shipFast() -> ShippingOptions:
    return ShippingOptions(_RealShipOpts(Carrier.FedEx, Conveyance.air))

def shipNormal() -> ShippingOptions:
    return ShippingOptions(_RealShipOpts(Carrier.UPS, Conveyance.truck))

def shipSlow() -> ShippingOptions:
    return ShippingOptions(_RealShipOpts(Carrier.USPS, Conveyance.train))

def shippingDetailed(
    carrier: Carrier, conveyance: Conveyance
) -> ShippingOptions:
    return ShippingOptions(_RealShipOpts(carrier, conveyance))

As a NewType, our public ShippingOptions type doesn't have a constructor. Since _RealShipOpts is private, and all its attributes are private, we can completely remove the old versions.

Anything within our shipping library can still access the private variables on ShippingOptions; as a NewType, it's the same type as its base at runtime, so it presents minimal¹ overhead.

Clients outside our shipping library can still call all of our public constructors: shipFast, shipNormal, and shipSlow all still work with the same (as far as calling code knows) signature and behavior.

If you need to build and convey some state within your public API, while avoiding breakages associated with compatibility churn, hopefully this technique can help you do that!

Acknowledgments

Thanks for reading, and thank you to my patrons who are supporting my writing on this blog. If you like what you've read here and you'd like to read more of it, or you'd like to support my various open-source endeavors, you can support my work as a sponsor.

22 May 2026 12:33am GMT