The uniffi::Record derive

The Record derive macro exposes a struct with named fields over FFI. All types that are supported as parameter and return types by #[uniffi::export] are also supported as field types here.

It is permitted to use this macro on a type that is also defined in the UDL file, as long as all field types are UniFFI builtin types; user-defined types might be allowed in the future. You also have to maintain a consistent field order between the Rust and UDL files (otherwise compilation will fail).

#[derive(uniffi::Record)]
pub struct MyRecord {
    pub field_a: String,
    pub field_b: Option<Arc<MyObject>>,
    // Fields can have default values
    #[uniffi(default = "hello")]
    pub greeting: String,
    #[uniffi(default = true)]
    pub some_flag: bool,
}