Check for updates periodically

[jqnatividad]

It would be nice if self_update incorporates an update check policy that works across platforms, where you can set a time interval between checks, so the next time the binary is run and the interval has passed, it will invoke the update automatically.

[jaemk]

Seems like a good idea. Maybe implemented as some struct that you pass a file path to where it can look for and save the last timestamp at which it checked, and then run a lambda against that timestamp? Some like

let f = xdg_dirs.place_config_file("last_update.stamp")?;
let g = UpdateGuard::new(f, |ts| {
    (now() - chrono::DateTime::parse_from_rfc3339(s)?) > Duration::from_secs(60 * 60 * 24 * 7)
})?;
if g.should_try()? {
    ...
    g.save_attempt();
}

[jqnatividad]

Great! Perhaps you can have a default of using the bin name to save the last_update.stamp file in a hidden directory (e.g. ".foo" for program ""foo").

Perhaps, there can even be a way for users to optionally specify their update preferences similar to how cargo.toml checks for semver (say "selfupdate.toml" in the same hidden directory) - so folks can pin to a specific version, or only allow patch updates.