Macro neli::impl_var_trait

macro_rules! impl_var_trait {
    (
        $( #[$outer:meta] )*
        $name:ident,
        $ty:ty,
        $impl_name:ident,
        $(
            $( #[cfg($meta:meta)] )*
            $var:ident => $val:expr
        ),*
    ) => { ... };
}

For defining a new enum implementing the provided marker trait. It accepts a name for the enum and the target type for serialization and deserialization conversions, as well as value conversions for serialization and deserialization.