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PyCon: PyCon US 2024 Sprints will be here before you know it!

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The Development Sprints are coming soon. Make sure you plan ahead:

When: Sprints will take place on May 20, 2024 8:00am through May 23, 2024 11:00pm EST

Where: At PyCon US at the David L. Lawrence Convention Center in rooms 308-311 and 315-321

Project Signups: Get your project listed so that attendees can help support it by signing up here Submit Sprint Project:

What are Sprints?

PyCon Development Sprints are up to four days of intensive learning and development on an open source project(s) of your choice, in a team environment. It's a time to come together with colleagues, old and new, to share what you've learned and apply it to an open source project.

It's a time to test, fix bugs, add new features, and improve documentation. And it's a time to network, make friends, and build relationships that go beyond the conference.

PyCon US provides the opportunity and infrastructure; you bring your skills, humanity, and brainpower (oh! and don't forget your computer).

For those that have never attended a development sprint before or want to brush up on basics, on Sunday, May 19th, there will be an Introduction to Sprinting Workshop that will guide you through the basics of git, github, and what to expect at a Sprint. The Introduction to Sprint Workshop takes place in Room 402 on Sunday, May 19th from 5:30pm - 8:30pm EST.

Who can participate?

You! All experience levels are welcome; sprints are a great opportunity to get connected with, and start contributing to your favorite Python project. Participation in the sprints is free and included in your conference registration. Please go to your attendee profile on your dashboard and indicate the number of sprint days you will be attending. 

Mentors: we are always looking for mentors to help new sprinters get up and running. Reach out to the sprint organizers for more info. 

Which Projects are Sprinting?

Project Leads: Any Python project can signup and invite sprinters to contribute to their project. If you would like your project to be included, add your project to the list. Attendees, check here to see if which projects have signed up so far.  

Thanks to our sponsors and support team!

Have questions? reach out to pycon-sprints@python.org

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jepler
3 days ago
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_considers attending the beeware sprint_
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Google is Experimenting With Running Chrome OS on Android

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An anonymous reader shares a report: At a privately held event, Google recently demonstrated a special build of Chromium OS -- code-named "ferrochrome" -- running in a virtual machine on a Pixel 8. However, Chromium OS wasn't shown running on the phone's screen itself. Rather, it was projected to an external display, which is possible because Google recently enabled display output on its Pixel 8 series. Time will tell if Google is thinking of positioning Chrome OS as a platform for its desktop mode ambitions and Samsung DeX rival.
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jepler
4 days ago
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> Google recently enabled display output on its Pixel 8 series.

oh that's interesting
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xdg and mime types - stuff I would've loved to know a week ago

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Learned a few things about xdg and mimetype registration in the last week that could be helpful to have condensed in a single place.

No Need to Ship a Mailcap Mime File

If you already ship a .desktop file (that is what ends up in /usr/share/applications/) which has a MimeType declared, there is no need to also ship a mailcap file (that is what ends up in /usr/lib/mime/packages/). Some triggers will do the conversion work for you. See also Debian Policy 4.9.

Reverse DNS Naming Convention for .desktop Files

Seems to be a closely guarded secret, maybe mainly known inside the Gnome world, but it's in the spec. Also not very widely known inside Debian if I look at my local system as not very representative sample.

Your hicolor Theme App Icon can be a Mime Type Icon as Well

In case you didn't know the hicolor icon theme is the default fallback theme. Many of us already install application icons e.g. in /usr/share/icons/hicolor/48x48/apps/ which is used in conjunction with the Icon field in the .desktop file to locate the application icon. Now the next step, and there it seems quite of few us miss out, is to create a symlink to also provide a mime type icon, so it's displayed in graphical file managers for the application data files. The schema here is simple: Take the MimeType e.g. application/x-vymand replace the / with a - and use that as file name in e.g. /usr/share/icons/hicolor/48x48/mimetypes/. In the vym case that is /usr/share/icons/hicolor/48x48/mimetypes/application-x-vym.png. If you have one use a scalable .svg file instead of .png.

This seems to be an area where Debian lacks a bit of tooling to automatically convert application icons to all the different sizes and install it in all the appropriate places. What is already there is a trigger to run gtk-update-icon-cache when you install new icons into one of the icon theme folder so they're picked up.

No Priority or Order in .desktop Files

Likely something that hapens on all my fresh installations: Libreoffice is installed and xdg-open starts to open pdf files with Libreoffice instead of evince. Now I've to figure out again to run xdg-mime default org.gnome.Evince.desktop application/pdf to change that (at least for my user). Background here is that the desktop file spec explicitly mandates "Priority for applications is handled external to the .desktop files.". That's why we got in addition to all of that mimeapps.list files. And now, after running the xdg-mime command from above, we've a ~/.config/mimeapps.list defining

[Default Applications]
application/pdf=org.gnome.Evince.desktop

Debian as whole seems to be not very keen on shipping something like a sensible default mimeapps.list outside of desktop environment specific ones. A quick search gave me just

$ apt-file search mimeapps.list
cinnamon-desktop-data: /usr/share/applications/x-cinnamon-mimeapps.list
gdm3: /usr/share/gdm/greeter/applications/mimeapps.list
gnome-session-common: /usr/share/applications/gnome-mimeapps.list
plasma-workspace: /usr/share/applications/kde-mimeapps.list
sxmo-utils: /usr/share/applications/mimeapps.list
sxmo-utils: /usr/share/sxmo/xdg/mimeapps.list

While it's a bit anoying to run into that pdf vs Libreoffice thing every now and then, it's maybe better to not have long controversial threads about default pdf viewer, like the ones we already had about the default MTA choices. ;) And while we're at it: everyone using Libreoffice should give a virtual hug to rene@ for taming that beast since 2010 and OpenOffice.org before.

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jepler
6 days ago
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things I wished I didn't know about xdg-mime: it parses xml files with sh+awk
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Forget aerobars: Ars tries out an entire aerobike | Ars Technica

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My brain registered that I was clearly cycling. My feet were clipped in to pedals, my legs were turning crank arms, and the arms were linked via a chain to one of the wheels. But pretty much everything else about the experience felt wrong on a fundamental, almost disturbing level.

I could produce a long list of everything my mind was struggling to deal with, but two things stand out as I think back on the experience. The first is that, with the exception of my face, I didn't feel the air flow over me as the machine surged forward down a slight slope. The second, related to the first, is that there was no indication that the surge would ever tail off if I didn't hit the brakes.

Living the dream

My visit with a velomobile was, in some ways, a chance to reconnect with a childhood dream. I've always had a fascination with vehicles that don't require fuel, like bicycles and sailboats. And during my childhood, the popular press was filled with stories about people setting human-powered speed records by putting aerodynamic fiberglass shells on recumbent bicycles. In the wake of the 1970s oil crises, I imagined a time when the roads might be filled with people cycling these pods for their commutes or covering long distances thanks to a cooler filled with drinks and snacks tucked in the back of the shell.

But the pods seemed to vanish from public consciousness as I got older, and I also learned that recumbent bikes are absolutely terrible on hills, which I'm now fond of climbing. The dreams had faded from my awareness when a reader, in response to one of our e-bike reviews, suggested I check out a velomobile. It turns out that my dreams weren't dead; they had just relocated to Europe without mentioning it to me.

Velomobiles are a product category with a variety of designs and manufacturers producing them, most of them based in Europe. They're also the fiberglass pods of my youth updated to current standards. Gone is the weight of fiberglass, and the one-off, hand-made hardware has been replaced by standardized models that have gone through refinements across generations. Safety features like lights, directionals, and mirrors are now standard.

But the prices, while not exorbitant (mostly in the $8,000–$10,000 range—for bicycles; you can pay more for far less carbon fiber), mean that living my childhood dream really wasn't an option. The European Union-based companies don't seem to have any agreements with US bike shops that would let me check one out in a showroom; I've heard of only two dealers in the US that keep velomobiles in stock, and neither is anywhere close to me. Fortunately, that didn't preclude the option of trying one. One major vendor of velomobiles, Romania's Velomobile World, has an ambassadors program, where people agree to let potential buyers take test rides in return for a discount on purchases.

That's how I found myself setting out for a short spin near the Maryland-Pennsylvania border in a Velomobile Bülk owned by Marc Rosen, who also fielded a lot of my questions about the hardware.


Page 2

A velomobile is typically a tricycle with two forward wheels and one in the rear (there's at least one four-wheel design). This adds stability that's critical for two reasons. The first is that there's a lot of flat surface to catch crosswinds, which could potentially topple a two-wheeled version over. The second, as mentioned earlier, is that these things are terrible on climbs since you can't force your entire body weight down on the pedals. Rosen said the three-wheeler's stability allows him to crawl up hills in an extremely low gear at a pace that might be slow enough to cause a two-wheeled bike to fall over.

The tricycle itself is a fairly standard recumbent setup, with the cranks in front and slightly above the seat, which can be adjusted for different riders' legs. The cranks typically have two chainrings and drive a chain that runs under the seat and to the rear axle, where there's a standard derailleur. Rosen went for internal gearing on his. Hardware called a Schlumpf Drive allows him to shift between two gearings with a flick of his heel: either a direct drive from the full 65-tooth crank ring or a gearing that reduces the effective crank ring by a factor of 2.5, which is better for handling hills.

On the Bülk, all of this hardware is accessible from the exterior via carbon fiber panels held in place by velcro. To avoid the weight, lack of aerodynamics, and complexity of hinges and latches, the Bülk uses velcro extensively.

It's typically recommended that you replace bike chains every 2,500 miles or so. But Rosen said that having a chain that's far more protected from the environment extends the lifetime of velomobile chains considerably—many riders don't find chain wear becomes extensive until 10,000 miles or more. That's probably a good thing, as the distance between the cranks and rear derailleur requires three traditional bike chains linked together.

While many of the existing models place some wheels in wells, on the Bülk, they're all fully encased. But the axle doesn't extend through the wheel, so it's possible to change tires and tubes simply by working your way around the wheel while operating on the small portion that extends below the bottom of the velomobile. Rosen said he typically flips his velomobile on the side on some grass, but he knows of other riders who carry blankets in the cargo space behind the rider. He also said that, in some of the company's earlier models, this cargo space is large enough to carry two spare wheels that can be swapped in if needed.

While the Bülk isn't an e-bike, it does have an electrical system. A rechargeable battery powers headlights, directionals, and tail lights (the precise details of many of these systems are user-configurable at purchase). Also reminiscent of powered vehicles: side-view mirrors on either side of the body. There's even a ventilation system, with an intake just under the nose in front leading to a vent pointed straight at the rider. The hood that covers the rider also has a vent that can be lowered to increase the airflow. After cooling you off, the air exits vents at the back.

All of this is encased in an extremely thin carbon fiber shell. In some ways, getting into the velomobile is like lowering yourself into a bathtub, except you need to be careful about only placing your feet where there's some structural support. The fit is also very snug; I couldn't lower my shoulders directly into the machine and had to duck them under the edge one at a time.

We also weren't certain that my knees would have clearance under the hood, even though it's shaped to specifically allow them a bit of space (I'm over 6 feet/190 cm tall, and much of that height is in my legs). There were some issues with my relatively large feet (US size 12/EU 46) hitting the shell as I pedaled; the cranks had three places to thread pedals in, so this could have been solved by moving the pedals inward.

The payoff for all that awkwardness? Aerodynamics. By the time a cyclist hits about 40 km/hr (25 mph), about 90 percent of the energy being put into the bicycle goes into overcoming the wind resistance. Get rid of much of that and it's possible to power yourself to some mind-blowing speeds. Compared to record-setting aero cycles, a velomobile gives up just a bit of aerodynamic efficiency for a massive dose of user-friendliness.


Page 3

So what's it like to ride one of these things? Despite having done so, I don't think I can offer a fair description. Nearly everything about the ride is different from my normal cycling experiences, and it's a lot to process all at once. For starters, the ground clearance on the Bülk isn't that substantial, so I tried to be very conscious of the pavement quality and avoid areas where the machine might bottom out.

This required using the steering, called a "tank" configuration, after the treaded vehicles. Two grips are at the end of short poles nestled up against the left and right side of the shell; pulling back on one turns the bike in that direction. This is also where the brake handles live, and one has a toggle switch that works the directionals.

Getting comfortable with the steering and brakes also competed with my brain's attempts to process the different sensations, as I mentioned above. One of the big sources of wind resistance that cyclists face is their own body; feeling the wind rushing over your shins is as much a part of the experience as feeling it on your face. And, well, it's not part of the velomobile experience. Having skipped the hood, I at least got a bit of a breeze on the upper part of my face, but it's possible to eliminate it entirely.

And then there's the speed. What really stood out was a slight down slope—one that was barely perceptible pedaling back up in the opposite direction. On one of my normal bikes, without pedaling, I'd probably accelerate a bit until the slope and wind resistance offset each other. In the velomobile, there was no indication that the wind resistance would ever slow things down—I'd run out of slope first. I had to hit the brakes simply because I didn't have confidence in my steering skills.

I fully expect that with more experience with the controls, I'd feel less burdened with figuring everything out and could simply enjoy the good aspects of what appeared to be a very well-made machine. But that would take some time.

Who’s this for?

The area where Rosen lives is pretty hilly, so he recommended a very short out-and-back. But the experience was enticing enough to leave me interested in taking him up on his offer to meet up when he takes his machines to someplace flat over the summer. I'd like to do a long enough ride to get comfortable with the practicalities of riding and focus more on the experience.

Would I want one myself? To an extent, I'm not the typical user. Scroll through the stories of the people who serve as velomobile ambassadors and you'll find a repeated theme: injuries that made using a traditional bicycle impossible, which forced dedicated cyclists onto recumbents. Later came the discovery of the velomobile as a better form of recumbent. (Rosen fits this description perfectly, with back problems relegating him to recumbents until the day a group of velomobiles blew past him during an organized ride.) The option to fully enclose the cabin also makes them appealing for people who ride in a variety of weather conditions—especially the cold and rain.

But they're clearly not for everyone. One major barrier is the high price—$10,000 is a lot to spend on an "every now and then" machine. You'll want to ensure your velomobile will get a lot of use, and that's not likely to be the case if it's just an addition to an existing stable.

Also, getting what I want out of cycling on a velomobile (meaning a few hours pushing pedals) would require a pretty long trip, which would be hard to do without spending time on some heavily trafficked roads. And that is tough to get enthused about, given my general lack of trust in drivers. Despite all the lights on the velomobile, I feel less confident that drivers would be fully aware of me compared to how I feel when I'm on my regular bicycle and positioned at eye level with them.

Would I like to see velomobiles take off, though? Absolutely. I still like my childhood visions of roads filled with human-powered commute machines. And this is the closest thing I've ever seen to that.

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jepler
7 days ago
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"It turns out that my dreams weren't dead; they had just relocated to Europe without mentioning it to me."
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acdha
7 days ago
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Washington, DC
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Automatically render images of your PCB with GitHub Actions

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kicad render action may be interesting for anyone who uses GitHub to host their
KiCad projects.

It’s a small Github Actions (WIP) that uses the KiCad nightly docker image to render a PCB image via the kicad-cli.

Currently it is using Kicad nightly since there is yet no Kicad release containing the image rendering command in the CLI.

See more on GitHub. Via X.

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jepler
13 days ago
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this is great
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Saturday Morning Breakfast Cereal - Trolley

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10 points to anyone who gets a paper published containing the term sack-blast.

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jepler
13 days ago
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if you don't find the answer obvious you may be affected by longtermism
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