Macro with_params_readonly 

macro_rules! with_params_readonly {
    (
        get $name:ident = $($key:ident).+ or $default:expr;

        $($body:tt)*
    ) => { ... };
    (
        set $($key:ident).+ = $val:expr;

        $($body:tt)*
    ) => { ... };
    ($($body:tt)*) => { ... };
}