is_colored/is_terminal API

[Rudxain]

I'm developing a program that prints sorted stats by default, but only when stdout is connected to a TTY:

let cli = Cli::parse();
let mut out = std::io::stdout().lock();
let must_sort = cli.sort.unwrap_or_else(|| out.is_terminal());

Then I realized that clap also performs an "is-TTY" check. I want to reuse that data in my app, to avoid duplicate code-gen and sys-calls.

It seems clap doesn't provide such "low-level" details, that's why I've opened this discussion.

Another alternative would be to support configuring clap to not perform the check, and instead rely on the user to provide the bool value themselves. This way, the user can check if stdout is a TTY in whatever way they want

[epage]

It seems clap doesn't provide such "low-level" details, that's why I've opened this discussion.

We intentionally keep our API surface focused for easier maintenance.

I want to reuse that data in my app, to avoid duplicate code-gen and sys-calls.

If the concern is build times, you can always use the same underlying library, either anstream or anstyle-query (depending on how low level you want to get).

As for runtime performance, the overhead should be unnoticeable especially considering everything else clap or the rest of a CLI will do. I'd recommend being guided by benchmarking and profiling.

Another alternative would be to support configuring clap to not perform the check, and instead rely on the user to provide the bool value themselves. This way, the user can check if stdout is a TTY in whatever way they want

We do have Command::color for overriding our logic at runtime. We do not have a way to avoid it at compile time without disabling all color support within clap. The main way to do that with features and features have a lot of usability problems and we already have more features than I care for. It doesn't seem worth it to break this down into finer grained features.