Selection formatting mode (VS Code v1.49 feature support)

[GriceTurrble]

Is your feature request related to a problem? Please describe. Visual Studio Code v1.49 offers a "modifications only" formatting mode, in which it will run the selected formatter only on modified lines of the file on save: https://code.visualstudio.com/updates/v1_49#_only-format-modified-text

However, Black cannot currently support selection formatting, so it is not possible to use this feature.

Describe the solution you'd like Add support for Black to format selected ranges of code within a file in support of VS Code's feature.

[ichard26]

Duplicate of #830 or #1352 depending on what kind of solution and workflow you want. #830 wants to add a --lines CLI option that tells Black which part of the code it is allowed to touch. While #1352 just wants Black to able to process indented code (which is probably a section of a file) and not error out. Of course #830 depends on #1352, but not the otherway around.

Thanks for the suggestion anyhow!