Allow good/warning/error/hint color to be customized

[milesj]

Please complete the following tasks

• I have searched the discussions
• I have searched the existing issues

Clap Version

3.0.0-rc.9

Describe your use case

I would like to use colored help/errors/etc in our CLI, but would like to change the colors to match our "brand".

Describe the solution you'd like

Provide a setting for good/warning/error/hint that allows the ANSI color code to be provided, based on the 256 table (or maybe 16m if you're crazy). https://upload.wikimedia.org/wikipedia/commons/1/15/Xterm_256color_chart.svg

It may be better to name the colors based on their actual usage, like arg/bin/label, etc.

Alternatives, if applicable

No response

Additional Context

No response

[epage]

One challenge with this is the API. We can't accept ANSI escape codes because clap3 intentionally added support for non-ANSI Windows terminals. We could copy the enums for color selections but we'd also need styling and the ability to compose them together. We end up starting to duplicate a decent chunk of a terminal styling API which we are hesitant to do (#1790 is a bit more extreme of an example).

We've been instead preferring for feedback on #2963 for improving our defaults and #2914 for allowing people to more thoroughly customize things when those defaults don't work.

It may be better to name the colors based on their actual usage, like arg/bin/label, etc.

We've been moving in that direction. Originally, it was named after the color but the color also implied some other styling with it. The next step is for us to split off --help parts from abusing the existing semantics and giving them their own. Since this is internal, this isn't too much of a priority though will be addressed as part of #2963 and #2389.

would like to change the colors to match our "brand".

Mind elaborating what is "ok" and what runs counter to your "brand"? In what way does it run counter?

[milesj]

@epage That all makes sense. I've had enough experience with ANSI and CLI tools so I totally get it.

As for the branding piece, the colors are shades of purple/blue/teal. Here's an example of the log output.

And this is where the colors are configured if you're curious: https://github.com/milesj/moon/blob/master/crates/logger/src/color.rs

[epage]

If you have any feedback or proposals for #2963, could you post it there?

Also, how important are errors or is the main concern the help?

Also, for anyone finding this issue, something that can help for re-evaluating is examples of precedence for this (like dialoguer) and proposals for how this would work either with older Windows support or why we can justify only supporting ANSI escape codes.

Otherwise, at this time I am closing out this issue, since there is no plan to grow the clap API to support this.

[epage]

Since this was closed, I've started work on https://github.com/epage/anstyle which aims to allow color definitions to be used in an API independent of the implementation which will allow users to define their stylesheet.

Blocked on https://github.com/epage/anstyle/issues/14