Macro wrap_keyboard_handler 

macro_rules! wrap_keyboard_handler {
    ($ vis : vis struct $ name : ident ; impl KeyboardHandler { $ ($ (# [$ attrs_name : meta]) * fn $ method_name : ident (& $ self : ident $ (, $ arg_name : ident : $ arg_type : ty) * $ (,) ?) $ (-> $ return_type : ty) ? { $ ($ body : tt) * }) * }) => { ... };
    ($ vis : vis struct $ name : ident $ (< $ ($ generic_type : ident : $ first_generic_type_bound : tt $ (+ $ generic_type_bound : tt) *) , + $ (,) ? >) ? { $ ($ field_vis : vis $ field_name : ident : $ field_type : ty) , * $ (,) ? } impl KeyboardHandler { $ ($ (# [$ attrs_name : meta]) * fn $ method_name : ident (& $ self : ident $ (, $ arg_name : ident : $ arg_type : ty) * $ (,) ?) $ (-> $ return_type : ty) ? { $ ($ body : tt) * }) * }) => { ... };
}

Implement the WrapKeyboardHandler trait for the specified struct. You can declare more members for your struct, and in the impl KeyboardHandler block you can override default methods implemented by the ImplKeyboardHandler trait.

Example

wrap_keyboard_handler! {
    struct MyKeyboardHandler {
        payload: String,
    }

    impl KeyboardHandler {
        // ...
    }
}

fn make_my_struct() -> KeyboardHandler {
    MyKeyboardHandler::new("payload".to_string())
}