default value based on os.

[madelaney]

I'm trying to look for a way to change the default value based off the OS. For example, I want to change the default path for the parameter config if the OS is FreeBSD/BSD vs. Linux vs. Windows.

#[derive(Clone, Parser, Debug)]
#[clap(author, version, about, long_about = None)]
pub struct Cli {
  /// The config file to load in.
  #[clap(short, long)]
  pub config: String
}

I tried to use a CONST and a function but neither worked and I couldn't find in the examples.

Any suggestions?

[madelaney]

I was able to solve this by using default_value_t instead of default_value.

#[derive(Clone, Parser, Debug)]
#[clap(author, version, about, long_about = None)]
pub struct Cli {
  /// The config file to load in.
  #[clap(short, long, default_value_t = config_path())]
  pub config: String,
}

fn config_path() -> String {
  if cfg!(os = "freebsd") {
    String::from("/usr/local/etc/service.yaml")
  }
  else {
    String::from("/etc/service.yaml")
  }
}