Add an optional flag in Derive mode

[tchaumeny]

Hi!

I have recently learnt Rust and used it with clap to write a simple program (an Ising model simulator, for those who know).

I have used the Derive method to declare my CLI options and one of these options (symmetry_breaking, see here) is a bool.

I'd like to be able to just pass --symmetry-breaking to set it to true but currently I have to pass --symmetry-breaking true.

I have tried different things but couldn't find a way to make it work, what should I do?

[epage]

Your flag is defined as

        /// Use the symmetry breaking boundary conditions
        #[arg(long)]
        symmetry_breaking: Option<bool>,

to get it to to not accept a value, you need to change it to

        /// Use the symmetry breaking boundary conditions
        #[arg(long)]
        symmetry_breaking: bool,

See also

• https://docs.rs/clap/latest/clap/_derive/_tutorial/chapter_2/index.html#flags
• https://docs.rs/clap/latest/clap/_derive/index.html#arg-types

[tchaumeny]

Thanks! Don't know how I missed that...