Validate interaction between args and subcommands

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Issue by JayiceZ
Monday Dec 06, 2021 at 10:56 GMT
Originally opened as TeXitoi/structopt#515

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Hi, I am new to structopt. And I am not sure is it a structopt issue or a clap issue? Here is the situation I met:

I defined it, like:

struct Opt {
    #[structopt(long)]
    cat: Option<String>,

    #[structopt(long)]
    dog: Option<String>,

    #[structopt(long)]
    host: Option<String>,

    #[structopt(subcommand)]
    cmd: Option<Cmd>,
}

enum Cmd {
    Test {
        #[structopt(long)]
        dir: Option<String>,
    },
    Debug{
        #[structopt(long)]
        remote: Option<String>,
    },
}

And what I want is: When Test SubCommand is set, one of cat and dog should be set(or it means that they are in a Group, and the group is required when Test is set); And when Debug is set, host should be set.

I have read the doc and examples, but I am not sure how to implement this function? 😭

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Comment by epage
Monday Dec 06, 2021 at 12:46 GMT

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From what I've seen so far, clap allows validation of relationship of args and groups but subcommands are effectively in another namespace, preventing them from interacting with that system.

In clap3, there is App::error to create clap-like errors for custom validation. There is also interest in generalizing clap's mechanisms so people are less likely to run into hurdles like this.

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This is also related to #1204

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See #3008 which should allow users to do this themselves