Papercuts in handle_local_options's return parameter

[A6GibKm]

The virtual method handle_local_options returns a glib::ExitCode, it is special cased so that the application exits when the return value is positive (e.g. ExitCode::FAILUE, ExitCode::SUCCESS) and continues to run when when negative.

Returning (-1).into() is an option, but it is not very nice.

[sdroege]

@A6GibKm Want to provide a PR for this? Docs say this:

   * Returns: an exit code. If you have handled your options and want
   * to exit the process, return a non-negative option, 0 for success,
   * and a positive value for failure. To continue, return -1 to let
   * the default option processing continue.

Now this just needs to be wrapped into meaningful types. All negative values are the same (default processing), 0 is success but no default processing, all values > 0 are errors and returned like that

[A6GibKm]

What I dont follow is when it is actually a return code? I will test later if 0 is a return code.

It could be an enum

LocalOptionsHandling {
    ExitCode(glib::ExitCode),  //  >= 0
    DefaultProcessing,  // -1
}

or something like that.