Feature or enhancement

In Python 3.13 we added colour output to the new REPL,traceback anddoctest, and in 3.14 tounittest,test.regrtest andcalendar, that can also be controlled with thePYTHON_COLORS,NO_COLOR andFORCE_COLOR environment variables:

• https://docs.python.org/3.14/whatsnew/3.14.html#unittest
• https://docs.python.org/3.14/using/cmdline.html#using-on-controlling-color

Let's add colour toargparse help output.

Survey

First, here's a survey of some other CLIs that use colour:

Survey

uv
cargo
composer
ruff
lsd
fd
	See also: bat, hyperfine, oxipng, zizmor
gh
rich-cli
typer

These fall into four groups:

• uv/cargo: green + cyan
• composer: yellow + green
• ruff/lsd/fd/gh: only bold
• typer/rich-cli: green + cyan + yellow

Prototypes

I've made prototypes of two of these (uv/cargo style, typer/rich-cli style), and another with blue + magenta similar to the 3.13 REPL/traceback.

Prototypes

main
uv/cargo style
typer/rich-cli style
REPL style

I think I prefer the typer/rich-cli style: the extra colour makes it easier to pick out the (green) short options from the (cyan) long options, and from their (green) arguments. And it should also be somewhat familiar to Python users who have used typer-based CLIs.

Linked PRs

• gh-130645: Add colour toargparse help #132323
• gh-130645: Add color to stdlib argparse CLIs #133380
• GH-130645: Default to color help in argparse #136809
• [3.14] GH-130645: Default to color help in argparse (GH-136809) #136886