Clarify documentation regarding AppSettings and child subcommand propagation

[andresv]

Clap 2.1.0

Example code is here (i have not yet pushed minor tweaks needed for clap 2.x, but overall concept is the same): https://github.com/cubehub/doppler/blob/master/src/usage.rs#L153.

If negative number like -6400 is given to --shift, i get this:

> cat ~/Downloads/rtl_fm_i16_raw_48k_145864_2.iq | ./target/debug/doppler const -i i16 -o i16 -s 48000 --shift -6400 > ~/Downloads/shifted.iq
error: Found argument '-6' which wasn't expected, or isn't valid in this context

[Vinatorul]

Thank you for example. I am not sure, but I think negative arguments should be passed in quotes. Let's wait for the @kbknapp answer.

[andresv]

I tried with quotes, still no go.

[kbknapp]

You have to use the AppSettings::AllowLeadingHyphen.

I'll leave this open until you can confirm that's working for you. 😉

[andresv]

Basically tried with that:

let matches = App::new("doppler")
            .setting(AppSettings::AllowLeadingHyphen)
            .version(env!("CARGO_PKG_VERSION"))
            .about("Compensates IQ data stream doppler shift based on TLE information, also can be used for doing constant baseband shifting")


            .subcommand(SubCommand::with_name("const")
                .about("Constant shift mode")
                .arg(Arg::with_name("SHIFT")
                   .long("shift")
                   .help("frequency shift in Hz")
                   .required(true)
                   .takes_value(true)))

            .get_matches();

And still got:

> cat ~/Downloads/rtl_fm_i16_raw_48k_145864_2.iq | ./target/debug/doppler const -i i16 -o i16 -s 48000 --shift -5700 > ~/Downloads/shifted.iq
error: Found argument '-5' which wasn't expected, or isn't valid in this context

[Vinatorul]

You should specify setting for subcommand, because it is also an App, like this:

let matches = App::new("doppler")
            .version(env!("CARGO_PKG_VERSION"))
            .about("Compensates IQ data stream doppler shift based on TLE information, also can be used for doing constant baseband shifting")
            .subcommand(SubCommand::with_name("const")
                .about("Constant shift mode")
                .setting(AppSettings::AllowLeadingHyphen)
                .arg(Arg::with_name("SHIFT")
                   .long("shift")
                   .help("frequency shift in Hz")
                   .required(true)
                   .takes_value(true)))

            .get_matches();

[kbknapp]

Ah ok, that's because the AppSettings only apply to the current command, and are not propagated down through child subcommands. This should be cleared up in the docs.

Edit: Oops @Vinatorul beat me to it! 😉

[andresv]

Very good now it works. I guess I can close it.

[Vinatorul]

@andresv thank you for response. I think it will be reclassified as documentation issue.
Negative values and subcomands are not clear enough