Set-formats on fresh text file based on configuration

[DancingQuanta]

This is an extension of a related issue #485.

I would like to be able to set the format on a fresh text file or modify the text file based on the current configuration (local if available else global) without specifying the argument to --set-formats.

For example, for the configuration in local .jupyter

# Pair notebooks
default_jupytext_formats = "markdown//md,notebooks//ipynb,scripts//py:percent"

and we have a a directory structure with a .md file in markdown directory:

.
├── .jupytext
├── markdown
│   └── intro.md
├── notebooks
└── scripts

And the pairing setup of the markdown file could be:

• Within parent directory

jupytext --set-formats markdown/00-intro.md

• or within markdown directory

jupytext --set-formats 00-intro.md

Above two command examples should be informed by the configuration that the markdown file is in the markdown directory.

To check what the current version (1.5.0) does, I ran both commands and got the same error

Traceback (most recent call last):
  File "C:\Users\at17\.conda\envs\sthm\Scripts\jupytext-script.py", line 9, in <module>
    sys.exit(jupytext())
  File "C:\Users\at17\.conda\envs\sthm\lib\site-packages\jupytext\cli.py", line 376, in jupytext
    exit_code += jupytext_single_file(nb_file, args, log)
  File "C:\Users\at17\.conda\envs\sthm\lib\site-packages\jupytext\cli.py", line 389, in jupytext_single_file
    raise ValueError("Cannot sync a notebook on stdin")
ValueError: Cannot sync a notebook on stdin

Is this usecase not yet supported or is there a different command I should use?
Lastly, I wonder if commandline operations can be used with the configuration which will save me from typing same arguments repetitively.

[mwouts]

Hello @DancingQuanta , that's an interesting example!

The problem here is that you pass a file name to the --set-formats option rather than a format name.

I am sure you're not the only one to try this... a few days ago I found myself doing jupytext --to dest_file.md which is wrong for the same reason (a format name is expected there, not a file name). So I'll think of adding a warning when the value passed to --from, --to and --set-formats is a file name 😃 (please don't close this issue so that I don't forget)

So, on your side, you should do jupytext --sync markdown/00-intro.md, or jupytext --sync 00-intro.md in the markdown folder, or even jupytext --sync markdown/*, i.e. use --sync, not --set-formats.

Lastly, I wonder if commandline operations can be used with the configuration which will save me from typing same arguments repetitively.

You should be able to use jupytext --sync markdown/* - or are you looking for something else?

[DancingQuanta]

Got it --sync is the right one here!

My suggestion on the warning message is to check is the argument match the format specification and warn about it.