PEP 8: Add green and red sidbar for good and bad examples

[hugovk]

As suggested in python/docs-community#22.

Like https://pep8.org, add green and red borders on the left side of "good" and "bad" code examples.

For example:

(This PR also removes redundant Version, Last-Modified and Content-Type headers, and Local Variables: footer.)

Accessibility check: colourblindness

We are not relying on colour to convey information; as before, the info about whether examples are good or bad is conveyed via the text.

We can later apply this to other good/bad code examples in other PEPs, such as the dangerous SQL code in PEP 675.

Question

I only added green/red for examples that are comparatively marked as correct or wrong (or similar). I left the other examples unmarked. But I think we could also mark those green, because they too are examples of good/allowed style. Thoughts?

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📚 Documentation preview 📚: https://pep-previews--3567.org.readthedocs.build/pep-0008/

[Rosuav]

Nice. I suspect this annotation can be put to use in quite a few places elsewhere too. Excellent enhancement IMO.

[hugovk]

Question

I only added green/red for examples that are comparatively marked as correct or wrong (or similar). I left the other examples unmarked. But I think we could also mark those green, because they too are examples of good/allowed style. Thoughts?

Would look like this:

• https://hugovk-peps.readthedocs.io/en/green-red2/pep-0008/

And give us extra green in places like:

• https://hugovk-peps.readthedocs.io/en/green-red2/pep-0008/#module-level-dunder-names

[encukou]

Thank you! This looks useful for me as for a non-colourblind reader. I'm sure it could be made more accessible, perhaps in a dedicated PR.

I think we could also mark those green, because they too are examples of good/allowed style.

It does look better to me :)

IMO, in that case the outdated with example should be red (or left without colour): https://hugovk-peps.readthedocs.io/en/green-red2/pep-0008/#maximum-line-length
(perhaps with a comment that it's only for Python 3.10 and below)

[hugovk]

Thanks, I've updated this PR to add those extra ones.

MO, in that case the outdated with example should be red (or left without colour): hugovk-peps.readthedocs.io/en/green-red2/pep-0008/#maximum-line-length
(perhaps with a comment that it's only for Python 3.10 and below)

Good point, I've left this one uncoloured:

https://pep-previews--3567.org.readthedocs.build/pep-0008/#maximum-line-length

[warsaw]

Good point, I've left this one uncoloured

What about a yellow border for examples like this?

The diff is a little difficult to read, but I'll trust that there aren't any content changes. The red/green borders are very nice! Thanks for doing this.

[hugovk]

Good point, I've left this one uncoloured

What about a yellow border for examples like this?

Something like this? https://pep-previews--3567.org.readthedocs.build/pep-0008/#maximum-line-length

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The diff is a little difficult to read, but I'll trust that there aren't any content changes. The red/green borders are very nice! Thanks for doing this.

Correct, no content changes.

Sphinx is stricter for .. code-block:: (needed for the class) than ::, so I had to adjust some indents.

[warsaw]

Re: yellow - yes, exactly. It looks pretty good in both light and dark themes. Thanks!

[hugovk]

Thanks for the reviews! Let's merge this, and we can then add to other PEPs where appropriate.