fieldvtable.rs

#[derive(Debug, PartialEq, Eq, Clone)]
struct Custo {
    pub d: i32,
}

/// A Struct with FieldVTable
/// a StruTypes enum will be generated too
#[derive(Debug, FieldVTableDerive)]
struct Stru {
    pub one: String,
    pub two: usize,
    pub three: Custo,
}

fn main() {
    let s = Stru { one: "test".to_owned(), two: 1312, three: Custo { d: 1 } };

    // It works as a trait object too
    let mut s: Box<dyn FieldVTable<StruTypes>> = Box::new(s);

    // Get field by name (as fast as a big match)
    if let Ok(StruTypes::two(n)) = s.get_field("two") {
        assert_eq!(n, 1312);
    }

    // Set field by name (again a big match)
    s.set_field("two", StruTypes::two(420)).unwrap();
    assert_eq!(s.get_field("two").unwrap(), StruTypes::two(420));

    // the generated enum wraps around the type of any field in the struct.
    // it is checked at runtime but doesn't render the type system useless.
    s.set_field("one", StruTypes::one("woah".into())).unwrap();
    s.set_field("three", StruTypes::three(Custo { d: 2 })).unwrap();

    assert!(s.set_field("four?", StruTypes::two(69)).is_err());
    assert!(s.set_field("one", StruTypes::two(69)).is_err());
}