Constructors

Firstly, when a Rust struct has synchronous new method, it will automatically become the default constructor in Dart. For example:

rust

pub struct MyStruct {
    ...
}

impl MyStruct {
    #[frb(sync)]
    pub fn new() -> Self { ... }
}

will become:

dart

var a = MyStruct(); // calls the `fn new()` on Rust side

The reason why the sync is needed is that, things are async by default to ensure Flutter thread (isolate) is never blocked.

Secondly, you can construct your object freely using whatever method name and synchronousness, and they will be simply static methods and nothing special happens. For example:

rust

impl MyStruct {
    pub fn new_with_name(name: String) -> Self { ... }

    #[frb(sync)]
    pub fn new_from_pieces(a: String, b: i32, c: Vec<u8>) -> Self { ... }

    pub async fn whatever_you_like(x: (String, String)) -> Self { ... }
}

can be used as:

dart

var a = await MyStruct.newWithName(...);
var b = MyStruct.newFromPieces(...);
var c = await MyStruct.whateverYouLike(...);