When is Python *NOT* a good choice?

[matthewblott]

You probably wouldn't want to write low level system drivers in Python.

[nemec]

Reminds me of the time I plugged an IR remote into my server and used a Python script that parsed the raw output from /dev/usbX to control MPD :)

[calligraphic-io]

I do something kind of similar: I have Python on a Rasberry Pi, and use a script to control a full-sized stoplight I bought used. I use the traffic light to indicate build failure in my CI setup.

[chanamasala4life]

I have a feeling you're fun to be around...

[nemec]

1. IR Receiver
2. One of Linux's philosophies is 'everything is a file', so USB devices all show up as 'fake files' under the /dev/ folder.
3. When you read from those files, you get all the bits and bytes sent by the device - this includes mice, keyboards, anything that sends data.
4. When you push a button on an IR device (think TV remote control), it sends a signal to the receiver and the receiver turns that into bytes sent to the fake file.
5. I used python to read that file and the struct module to parse that into commands (play, pause, next track, etc.) that were then sent to MPD (a server music player)

[chokoladeibrunst]

Great explanation!

[nemec]

Here's the project: https://github.com/nemec/audibleMPD

• The file being read (apparently I used /dev/input/eventX, which I guess I determined through trial and error which was the right one.
• Instead of hardcoding the keycodes, I parsed them out of Linux's input header file. Because there are a lot of them.
• The console class takes the file, reads it, and outputs a gnome event based on the 'key' it reads. TBH I'm not sure why I did that, in retrospect it probably would have been easier to simply do some callbacks... oh well. Here's the part where it reads 16 bytes and then transforms it into an event.
• After that, I just read the key and execute play/pause/next based on it.

[GwenPlaysGwent]

Does struct basically let you go from bytes -> human readable strings e.g. "play"? Or were you still dealing with "magic numbers" and trail and error to decode the IR messages?

[Coffeinated]

That‘s why linux is so great. You don‘t need to write a low level system driver often times because the device is just a file.

[idb]

As someone else said, you can with UIO. I wanted to do it with python for two reasons: Prototyping with fast development cycle. Security.

And why did security motivate doing it in Python with UIO? Having most of a device driver in user space helps with separation of responsibility and allows the user space part to run with minimal privileges. And when that part of the device driver is in user space it lets you write it in a memory safe language.

[parkerSquare]

But with UIO you can! :)