Force color

[darrenburns]

Type of changes

• [ ] Bug fix
• [x] New feature
• [ ] Documentation / docstrings
• [ ] Tests
• [ ] Other

Checklist

• [x] I've run the latest black with default args on new code.
• [x] I've updated CHANGELOG.md and CONTRIBUTORS.md where appropriate.
• [x] I've added tests for new code.
• [x] I accept that @willmcgugan may be pedantic in the code review.

Description

Adds support for FORCE_COLOR environment variable. Presence of this variable in the environment results in Console.force_terminal = True. If FORCE_COLOR and NO_COLOR are both set, NO_COLOR takes priority.

NO_COLOR = 1 only

NO_COLOR = 1 and FORCE_COLOR = 1

FORCE_COLOR = 1 only

[codecov-commenter]

Codecov Report

Merging #2449 (0162d17) into master (19e518f) will decrease coverage by 0.11%. The diff coverage is 98.38%.

@@            Coverage Diff             @@
##           master    #2449      +/-   ##
==========================================
- Coverage   98.71%   98.59%   -0.12%     
==========================================
  Files          73       72       -1     
  Lines        7771     7769       -2     
==========================================
- Hits         7671     7660      -11     
- Misses        100      109       +9     

Flag	Coverage Δ
unittests	98.59% <98.38%> (-0.12%)	:arrow_down:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
rich/default_styles.py	100.00% <ø> (ø)
rich/logging.py	100.00% <ø> (ø)
rich/progress.py	92.76% <ø> (ø)
rich/scope.py	100.00% <ø> (ø)
rich/segment.py	98.72% <93.10%> (+<0.01%)	:arrow_up:
rich/_inspect.py	100.00% <100.00%> (ø)
rich/box.py	100.00% <100.00%> (ø)
rich/cells.py	96.05% <100.00%> (-3.95%)	:arrow_down:
rich/color.py	100.00% <100.00%> (ø)
rich/console.py	97.67% <100.00%> (-0.62%)	:arrow_down:
... and 6 more

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[darrenburns]

@willmcgugan would appreciate a review here when you get a chance.

[hugovk]

Thank you for this!

Do you have a rough idea of when the next release is?

Would be great to get this released, integrated and tested into pip in time for their next release some time on October.

[willmcgugan]

Potentially as soon as this weekend.

[henryiii]

And it’s out! <3

[webknjaz]

(discoverability comment) PSA: looks like using NO_COLOR for overriding FORCE_COLOR is currently broken:

• https://github.com/Textualize/rich/issues/2924
• https://github.com/pypa/pip/issues/12405

[henryiii]

I believe the problem is that this is handled unusually: if both NO_COLOR and FORCE_COLOR are set, instead of avoiding ANSI escapes, it instead makes everything black and white, but still uses ANSI escapes for things like bold text. (Personally, I prefer controlling color by the value of FORCE_COLOR; in plumbum I use the value for the color mode).

[willmcgugan]

I asked the author of the NO_COLOR spec, and he confirmed that NO_COLOR wasn't intended as a strip all escape sequences switch. i.e. bold / italic etc isn't considered color.

[hugovk]

For reference: https://github.com/jcs/no_color/issues/240

[henryiii]

I’m not sure that’s the correct reference. That one says monochrome is still color. :)

A big part of the problem is you can’t set NO_COLOR to an empty string or some sort of false value (that’s part of the spec). Unsetting an environment value is sometimes hard (there’s no “none” in TOML, for example, which means tools like cibuildwheel and scikit-build-core can’t undo a set variable via static config since there’s no way to indicate it). But that’s part of the spec, not much that can be done.

[webknjaz]

I asked the author of the NO_COLOR spec, and he confirmed that NO_COLOR wasn't intended as a strip all escape sequences switch. i.e. bold / italic etc isn't considered color.

Honestly, reading https://github.com/jcs/no_color/issues/240 I interpreted it differently..

Also, I don't think that “bold” is a good example, since some terminals don't implement it properly and abuse it for making the color brighter. I hit this with Kitty, which implements the standard to the letter and when some apps misuse it, they sometimes ends up printing “invisible” color (as in black on black).

[webknjaz]

I’m not sure that’s the correct reference. That one says monochrome is still color. :)

A big part of the problem is you can’t set NO_COLOR to an empty string or some sort of false value (that’s part of the spec). Unsetting an environment value is sometimes hard (there’s no “none” in TOML, for example, which means tools like cibuildwheel and scikit-build-core can’t undo a set variable via static config since there’s no way to indicate it). But that’s part of the spec, not much that can be done.

Exactly, in my case, it's YAML, which does have None through ~. But the context is GHA where you can only override environment variables, but not unset them on the workflow level.

[webknjaz]

@willmcgugan so it looks like the combination of env vars like FORCE_COLOR= NO_COLOR=1 ends up forcing non-color ANSI escape codes.

One would expect that NO_COLOR would neuter FORCE_COLOR (as in, has the exact opposite effect). But in practice, the latter forces color and non-color ANSI-codes and the former only cancels out the color ANSI-codes.

This brings up a question — which ANSI-codes constitute color? You mentioned bold/italic being non-color, so why does FORCE_COLOR implies enabling them, then?

https://force-color.org suggests that FORCE_COLOR should enable color ANSI escape codes, but it seems like Rich does more than that.

Command-line software which outputs colored text should check for a FORCE_COLOR environment variable. When this variable is present and not an empty string (regardless of its value), it should force the addition of ANSI color.