Adding Custom Formatters

To define a custom formatter, you can do so in the Jupyter notebook configuration (usually found ~/.jupyter/jupyter_notebook_config.py or something along those lines), the following example adds a rather useless formatter as a example.

from jupyterlab_code_formatter.formatters import BaseFormatter, handle_line_ending_and_magic, SERVER_FORMATTERS

class ExampleCustomFormatter(BaseFormatter):

    label = "Apply Example Custom Formatter"

    @property
    def importable(self) -> bool:
        return True

    @handle_line_ending_and_magic
    def format_code(self, code: str, notebook: bool, **options) -> str:
        return "42"
        
SERVER_FORMATTERS["example"] = ExampleCustomFormatter()

When implementing your customer formatter using third party library, you will likely use try... except in the importable block instead of always returning True.

Remember you are always welcomed to submit a pull request!