How to let clap v4 allow multiple occurrences?

help
1

I want my program to allow multiple occurrences of a flag. The flag isn't a vector, so action = ArgAction::Append doesn't work for me, and I want the last occurrence to take priority. I haven't found any way to do this yet.

struct Args {
    /// Input files
    files: Vec<String>

    #[arg(short, long, default_value = "mystruct")]
    flag: MyStruct
}

With my current code, running my_program --flag value1 --flag value2 raises an error:

error: the argument '--flag <FLAG>' cannot be used multiple times

Usage: my_program [OPTIONS] [FILES]...

For more information, try '--help'.
1 Like
2

You can use overrides_with.

#[derive(Parser, Debug)]
struct Args {
    /// Input files
    files: Vec<String>,

    /// A flag that can be specified multiple times; last occurrence wins
    #[arg(short, long, default_value = "mystruct", overrides_with = "flag")]
    flag: MyStruct,
}
1 Like
3

Thanks! But is there a way not to repeat it for every argument? If not, that's okay.

1 Like
4

I am not sure if there is a way to set it globally, but I think using it on each field individually should work.

1 Like
5

There is args_override_self.

#[derive(Parser)]
#[command(args_override_self = true)]
struct Args {
    /// Input files
    files: Vec<String>

    #[arg(short, long, default_value = "mystruct")]
    flag: MyStruct
}
4 Likes
6

Thank you so much!