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Methods

There is support for structs with methods. Both static methods, and non-static methods are supported. No special syntax is needed, and just write normal impl YourStruct { pub fn your_method() {} }.

Methods in external crates​

For methods that are not defined in the rust_input folders in the current crate, the #[frb(external)] syntax (see example below) is needed to make flutter_rust_bridge aware of the methods.

Example​

Example 1: Methods in same crate​

pub struct SumWith { pub x: u32 }

impl SumWith {
    pub fn sum(&self, y: u32) -> u32 { self.x + y }
    pub fn sum_static(x: u32, y: u32) -> u32 { x + y }
}

Becomes:

class SumWith {
  final int x;

  const SumWith({
    required this.x,
  });

  Future<int> sum({required int y, dynamic hint}) { ... }

  static Future<int> sumStatic({required int x, required int y, dynamic hint}) { ... }
}

Remark: If you are curious about Future, have a look at this.

Example 2: Methods in external crates​

Suppose we have these in external crates:

pub struct MyExternalStruct {
    ...
}

impl MyExternalStruct {
    pub fn simple_external_method(&self) -> String {
        // ... some long implementations ...
    }
}

Then, we only need to repeat the function signatures in our main crate as follows:

#[frb(external)]
impl MyExternalStruct {
    pub fn simple_external_method(&self) -> String {}
}

Remark: Just leave the function body empty (i.e. {}), no need to put anything there.

This feature is compatible with the mirroring feature as well.