Back to being a "Duty Programmer"

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I’ve been using AI to write code for a while. Up until recently I was just asking ChatGPT questions and then copying its answers into Visual Studio Code. This works fairly well and is good for me because I have a ChatGPT subscription. But, having seen what Claude can do inside Visual Studio Code I thought I’d give that a whirl.

At around 4:00pm today I decided to add rotary encoders to my Python powered Connected Little Boxes. I wanted an encoder manager that would generate events that other mangers could use to control things. Claude looked at the pattern for other managers and built the manager for me. Then I asked it to make a lamp manger that uses two encoders to control the brightness and colour of a pixel lamp. It did that too. But it didn’t quite work. I took a look at the code and had the following conversation with Claude:

This is exactly what I would have said to a human developer who had come to me and shown me their code (I typed the bit at the top). Claude took the input, modified the relevant source files and the device now works perfectly.

My first role when I graduated included working as the “Duty Programmer”. I sat in an office next to Computer Reception and any user with a problem could come along, show me their code listing and I would suggest how to fix it. I loved the work. New puzzles every day.

One of the best things about the job was that sometimes you didn’t have to have any understanding of the software being shown to you. The user would get half way through describing the fault and then say “Aha! That’s what it is!” and go off and fix it themselves. Turns out explaining a problem to someone else often ends up with you fixing it.

But on the occasions they were properly stuck I’d have to dig into their code and help them work out what was going wrong. After a few years I got quite good at it. And now I seem to have come full circle in my career. Only I’m not looking at code written by someone else, I’m looking at code written by something else. Interesting times.

Visually Explained Videos are Wonderful

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Python is a wonderful programming language. But, like most languages, there are things about it that you just have to know. You can’t infer the existence of things like *args and **kwargs. You need to be told about them, what they do and how best to use them.

The Visually Explained series of videos does a fantastic job of placing Python elements in context. It covers lots of fiddly things about the language which are super powerful but you might not know about. They are impeccably presented and just the right length. If there’s something you’re grappling with, or you just want to broaden your Python horizons, you should take a look at them.

Polaroid OneStep

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This is a nifty little camera from a while back. It takes Polaroid 600 film and has a funky flash flip up front. I got this one at the same time as I got the Polaroid MiniPortrait. I’m not sure which was thrown in with which. The camera works well. I love the way that when you move the slider on the left from tree to flower it slides in another lens to adjust the focus . Both lenses are plastic, so you don’t get anything tack sharp. But you do get pleasing colours and contrast.

There’s not that much more to say about it really. The flash normally fires for every picture. If you don’t want flash you can press the button which is wrapped around the release to trigger the shutter on its own (but you’d best brace the camera against something solid or you might be entering a world of camera shake).

If you want to dip your toe in instant photography you can pick these up pretty cheaply and they look really cool (I think) which is nice.

This shot shows the limits of the close focus. The bottoms of the vases are nice and sharp, but the flowerheads are a bit blurred because they are closer to the camera. But it made a good job of exposure and lighting.

Insights from Octopus

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You don’t say

We had our gas and electricity meters replaced yesterday with new smart ones. The process was quick and efficient. Although it felt strange to be in a house where nothing worked for the hour or so it took to swap the electricity one. The data feeds seem to be working now, although it might take a bit of time for the insights to catch up.

I was looking forward to getting a gadget to put in the kitchen to monitor my energy usage, but these aren’t given away anymore. Apparently nobody uses them and they end up in the back of a drawer. Everything can be done via the app. I’m tempted to see if I can’t make something to provide a display.

We did have a brief go with Agile Octopus a while back but we gave up when the prices reached the point where it was impossible to do things economically for long periods of the day. Perhaps we’ll take a look at some of the more adventurous tariffs in the future. I’m just looking forward to not having to submit meter readings every month.

FreeCAD Python Indent Settings

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Make sure that “Keep Tabs” is switched off

Layout is important in Python. How code is indented tells the compiler when code runs. You can indent your program text using tabs or spaces but you need to be consistent about this. Otherwise you will get impossible errors telling you that some of your code is wrong when it looks exactly right on the screen.

By default the Python editor in FreeCAD uses tabs to indicate indents. However, lots of other programs don't. If you use something like ChatGPT to make some code to paste in your FreeCAD program you might have lots of indenting errors when you try to run it. Or at least, I did.

There's no neat solution to this but you can make your life much easier by telling FreeCAD to use spaces for indents, rather than tabs. You can do this on the Edit>Preference menu at the Python Editor tab. This lets you set tab and indent sizes. Change the setting from "Keep tabs" to "Insert spaces".

Miniportrait pictures

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The picture above was taken with the new (to me) Polaroid Microportrait camera that I got yesterday. I had to put the camera and my Lomo Graflok Instax film back in a dark bag, extract a sheet of film from the film back and load it into the camera, take the camera out of the bag, take the shot, put the camera back in the dark bag, take the sheet of film out of the camera, put it back in the film back, take the film back out of the dark bag and eject the film to process it. Not something I’ll be doing again in a hurry.

Instax film is smaller than the original pack film so the images don’t fill the frame properly. I had to guess the exposure a bit because I wasn’t sure how powerful the flash was and I’m not convinced I set the focus properly. The results show potential though. I’ll try a few more later.

The camera is extremely restricted in terms of what you can do with it. The lens is fixed focus, for portraits of people. You can adjust the aperture, but there are only two shutter speeds available. Having said that, it does take the pictures very well and is super fun to use.

I’ve discovered that you can still get packs of film for it, but they stopped making new film over twenty years ago and what is left (which might not work) is selling for at least ten pounds a shot. You do get four pictures per shot though. Perhaps when I’m rich…

What I plan to do next is make a back that will let me use sheet film with camera. A sheet of 4x5 film will cover the entire image with room to spare. Then I will be able to take super high quality portraits.

Polaroid Miniportrait - four pictures in one

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Got given this today. Well, it was free with another camera I bought. But what a beauty! It’s a Polaroid MinPortrait which was made for taking passport pictures and the like. You can set it to take four shots at the same time, giving four identical pictures, or you can take individual or dual images. It has ultrasonic focusing, a beefy flash (that works) and it is all round awesome. Only snag is that you can’t get the film for it anymore. But I’ve got plans involving Instax Wide instant film. Great fun.

Python Shorts 18: Unpacking tuples and passing them as arguments

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Tuples are a great way to group data together. Say I want to pass into a function the minimum and maximum values for a particular random item. Say I was writing a function to draw stars, and I want to make random ones with points in the range 5 to 20. I can make tuple like this to express the requirement.

points_min_max=(5,20)

This makes me a tuple with the two values. However, when I call random.randint from the random library it wants two individual arguments. I could do this by getting each value out of the tuple and passing it into the call:

random.randint(points_min_max[0],points_min_max[1])

This is not very elegant, and it would be a real pain if I wanted to pass lots of tuple values. So, instead Python lets you do this:

random.randint(*points_min_max)

We just have to specify the name of the tuple variable, preceded by a * which in this context means "unpack". When the function or method is called Python will convert the values in the tuples into individual arguments and then pass those. The order of the arguments matches the order of the values in the tuple.

You can find all the Python Shorts here.

Fun with Fonts in FreeCAD

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I hate it when reality breaks. I hate it when I have two facts, both incontrovertible and mutually exclusive. It happened today in FreeCAD. I’ve got a program that makes 3D wordsearches. At one point the program goes off and finds a font file it then uses for character designs. I wanted to make a version that runs on the Raspberry Pi, so I did some due diligence (had a look in the fonts folder on the Pi) and found a path to the font file I wanted to use. I then put that path into my program and expected it to just work. It just didn't. The font file was not found. Which was annoying. After I’d convinced myself that the filename was correct (which took a while) I  asked FreeCAD to show me the files it could see in each environment:

Shurely Shome Mishtake..

The screenshot above shows what I got. In the console at the top you can see the files that the Raspberry Pi has in its font folder. Underneath you can find the files that a Python program running in FreeCAD can see. I’ve got two different views of what should be the same part of the file system. Wah!

After a few minutes I figured it out. The easiest way to get FreeCAD to run on a Raspberry PI is to install it as a Flatpak application. I even explain how to do it here. It works a treat. Unfortunately, Flatpak exposes a different reality to programs that run within it it. This is all to do with making them portable across different platforms. So my fonts weren’t where I was expecting them to be. All I had to do was use a font path which made sense in the Flatpak universe and all was well.

There’s useful lesson here. If things don’t seem real, it might be because your program might be running in a different reality.

Lego's new Smart Brick looks fun

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Lego have just launched a new Smart Play system. It’s based around a Smart Brick that contains an embedded processor which enables the brick to make sounds, flash lights and react to movement. They’ve created a custom ASIC (Application Specific Integrated Circuit) to control everything and added wireless charging for the tiny internal battery. The charging coil used to get power into the brick is also used for brick-to-brick communication and to talk to the other two components in the system, plates and minifigures which contain NFC (Near Field Communication) chips. Plus, and this is the really interesting part for me, the charging coils can also be used to allow one smart brick to tell the location of another.

The less interesting part for me is that none of this is programmable, at least at the moment. The bricks run custom firmware which executes built-in routines triggered by external events. This means that you are limited to what behaviours have been hard wired into the devices and so that the kit has much more in common with the Lego Mario smart devices than with Lego Mindstorms. However, there is also a Bluetooth interface in each brick which can talk to an app, so maybe in the future your might be able to string together behaviours to bring your ideas to life.

The first Lego Smart Play sets come out in March and you’ll be able to reserve them in a couple of days. But you’ll need deep pockets. The sets are all Star Wars branded, which means that as well as a smart premium you’re also paying extra for licencing. I’m still tempted though…

Developing Nicely

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Always fancied one of these cars, but I don’t think I’d fit into it

We spent some time yesterday developing colour film. This went surprisingly well and I really like the results. We used these chemicals which make colour development as easy as black and white. We did the first batch of prints at the end of November. It’s nice to know that the chemicals keep for a reasonable time.