Python: Black doesn't wrap long lines

Question

I am using black==20.8b1.

I have a long string like:

return f"{self.name}, a {adjective.to_name()} {kin_string}{self._type.to_name()} who works for the {target.get_relationship_target_string()}."

I run:

$ black -l 80 . -t py38
All done! ✨  ✨
2 files left unchanged.

Why is the string not wrapped? I thought that black supports wrapping strings now (based on issues in github).

score 29 · Answer 1 · edited Sep 21 '22 at 15:22

29

Currently we have to add --experimental-string-processing tag to it. I think in future versions it will be made default.

black -l 80 --preview file.py

edited Sep 21 '22 at 15:22

develmusa

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answered Nov 09 '20 at 08:28

Eka

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Looks like we have a new flag to replace `--experimental-string-processing now`: `--preview`. When running with `--experimental-string-processing`: `:12: Deprecated: `experimental string processing` has been included in `preview` and deprecated. Use `preview` instead.` – Taylor D. Edmiston Apr 06 '22 at 18:17

GG. · Answer 2 · 2022-07-04T17:06:02.253

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Since 22.1.0 (Jan 29, 2022), you have to run Black with --preview.

edited Jul 04 '22 at 17:06

answered May 03 '22 at 21:36

GG.

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Thank you! This works for me when I do `black --preview file.py`. How can this work in VScode? I have included `"python.formatting.blackArgs": [ "--preview" ]` in my project's settings.json, but line wrapping is not enforced. – KLaz Oct 20 '22 at 11:38
@KLaz not really sure. These are my settings in VSCode: `"python.formatting.provider": "black", "python.formatting.blackArgs": ["--preview"]` (on MacOS). Looks like we have the same. It works for me. Does your VSCode succeed to format a file in Python (I mean, other than the line wrapping)? Maybe it can't find the Black binary on your system. – GG. Oct 20 '22 at 16:06

Ronald Pereira · Answer 3 · 2020-08-31T13:55:15.210

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Currently, Black doesn't wrap long strings or long comments. You can see an open issue in their project GitHub saying:

Black currently doesn't wrap long string literals or merge string literals that happen to be on the same line. [...] It would require modifying the AST which isn't 100% safe and has a bunch of edge cases to be dealt with.

edited Aug 31 '20 at 13:55

answered Aug 31 '20 at 03:53

Ronald Pereira

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Do you know why this issue is closed https://github.com/psf/black/issues/182 I thought it was already done? – gruszczy Aug 31 '20 at 15:38

Python: Black doesn't wrap long lines

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