mpremote exec: semicolon for "one-liners" works. Will it alway work?

[DavesCodeMusings]

I've been looking for a way to run multiple MicroPython statements on one line using mpremote exec. It seems the semicolon works similar to the way one would expect in a BASH shell.

PS C:\> py -m mpremote exec "from os import listdir; print(listdir())"
['boot.py', 'device_specs.py']

This is fabulous, but also unexpected since Python doesn't end lines with semicolons like other languages. mpremote exec doesn't seem to mind the spaces trailing the semicolon either. Serendipity!

But, didn't see this feature mentioned in any documentation.

I'm happy it works, but is it an intentional feature? If I start writing exec strings like BASH one-liners will it break in some future release of mpremote?

[jimmo]

This is standard Python (and therefore MicroPython). Semicolons are optional as a statement separator in Python.

[jimmo]

And just to be clear w.r.t. your question, none of this is being handled or interpreted by myremote.
mpremore just passes the exec command directly to the REPL.

[DavesCodeMusings]

Thank you for the explanation. I was always under the impression that semicolons were taboo in Python. I learned something new today.

[peterhinch]

They are allowed by the language. Some disapprove of them on style/readability grounds, although PEP8 doesn't seem to have a view.

[DavesCodeMusings]

Here's a couple one-liners I came up with in the end...

Show the files in a directory:

from os import listdir, stat ; print([entry for entry in listdir() if stat(entry)[0] & 0x8000 != 0])

Show the subdirs in a directory:

from os import listdir, stat ; print([entry for entry in listdir() if stat(entry)[0] & 0x4000 != 0])

My goal was to use mpremote exec to grab a list of files from the microcontroller and then offer a selection list in a Visual Studio Code extension. The output from the one-liners is close enough to JSON that it can be parsed by the VSCode extension without much trouble. Just wanted to share in case anyone else is thinking of doing something similar.

[peterhinch]

You might be interested in this. It enables mpremote to be extended with your own custom scripts. For example I can run

$ mpremote wifi_connect

and mpremote will copy wifi_connect.py to the target's RAM and execute it.

[DavesCodeMusings]

That looks pretty cool.