Tuple arguments (e.g. --user login password)

[max-ishere]

I had 2 subcommands and for consistency I wanted to have an optional config file as an optional positional. However, in one of the commands I also had to specify additional information. Here is an example:

$ app do1 [config]
$ app do2 [config] [-a <address> <port>] # address and port may/not be required

Ideally do2 would become

struct Subcommand {
    Do2 {
        config: Option<String>
        address: (String, u16),
        // or
        address: Option<(String, u16)>,
    }
}

But they cannot. One solution would be:

Do2 {
    // both address and port are required
    address: String,
    port: u16,
    config: Option<String>,
}

But if you have port and address as optional, and you want the syntax in the example (-a <ADDR> <PORT>), you will need to make an optional subcommand a. But that's confusing because in help you don't see a, you see <COMMAND>:

$ app help do2

app do2 [config] [<COMMAND>]
# what should be there:
app do2 [config] [-a <ADDR> <PORT>]

[epage]

Our issue for this is #1717

The main problem is we only allow one value_parser per argument and need a design for how to specify value parsers per value.

One workaround is to have them be two separate flags that require each other

#[arg(short, long, requires = "port")]
addr: String,
#[arg(short, long, requires = "addr")]
port: u16,

The other is to parse the value after parsing clap.