Macro sarge::get_val

macro_rules! get_val {
    ( $parser:ident, short, $tag:expr ) => { ... };
    ( $parser:ident, long, $tag:expr ) => { ... };
    ( $parser:ident, both, $short:expr, $long:expr ) => { ... };
}

Like get_arg!, but instead returns an option containing its ArgValue

Example:

use sarge::{arg, get_arg, get_val, Tag, ArgType, ArgValue, Argument, ArgumentParser};
 
let mut parser = ArgumentParser::new();
parser.add(arg!(flag, long, "help"));
parser.parse_args(vec!["abc".into(), "--help".into()]);

assert_eq!(get_val!(parser, long, "help").expect("Failed to get argument value"), ArgValue::Flag(true));