Have an argument imply others and set them?

[classabbyamp]

I'd like to have a flag that sets other flags, like --packaging implies --system --skip-pkginfo, and also sets system and skip_pkg_info to true.

This is what I'm currently doing:

#[derive(Args, Clone)]
pub struct InstallCmd {
    #[clap(
        long = "system",
        help = "Perform a system-wide installation",
        global = true
    )]
    pub system: bool,
    #[clap(
        short = 'D',
        long,
        requires = "system",
        help = "Install all the files relative to this directory",
        env
    )]
    pub destdir: Option<String>,
    #[clap(
        long = "skip-pkginfo",
        help = "Skip the installation of rinstall pkginfo, used for uninstallation"
    )]
    pub skip_pkg_info: bool,
    #[clap(
        long,
        help = concat!("Enable flags needed for packaging (enables --system",
                       " and --skip-pkginfo, requires --destdir)"),
        conflicts_with_all(["skip_pkg_info", "system"]),
        requires = "destdir"
    )]
    pub packaging: bool
}

impl InstallCmd {
    pub fn system(&self) -> bool {
        self.system || self.packaging
    }
    pub fn skip_pkg_info(&self) -> bool {
        self.skip_pkg_info || self.packaging
    }
}

[epage]

In #4793, I've started gathering thoughts for how to add support for this without in a more extensible way