https://github.com/dymk/tui-rs/blob/dymk--interactive-form/src/interactive_form/macro_impl.rs

01_macro_invocation.rs

use tui::widgets::TextInputState;
tui::interactive_form_state!(struct Foo {
    bar: TextInputState = "baz",
    quux: TextInputState = "smaz",
    whup: TextInputState
});

02_expanded.rs

use tui::widgets::TextInputState;
struct Foo {
    focused_state_idx: Option<usize>,
    bar: TextInputState,
    quux: TextInputState,
    whup: TextInputState,
}
impl Foo {
    pub fn input_states_len() -> usize {
        <[()]>::len(&[(), (), ()])
    }
    #[allow(unused_variables)]
    pub fn input_state_at(
        &self,
        idx: usize,
    ) -> Option<&dyn crate::widgets::InteractiveWidgetState> {
        if 0 == idx {
            Some(&self.bar)
        } else {
            if (0 + 1) == idx {
                Some(&self.quux)
            } else {
                if ((0 + 1) + 1) == idx {
                    Some(&self.whup)
                } else {
                    None
                }
            }
        }
    }
}
impl std::default::Default for Foo {
    fn default() -> Foo {
        #[allow(unused_imports)]
        Foo {
            focused_state_idx: None,
            bar: "baz".into(),
            quux: "smaz".into(),
            whup: Default::default(),
        }
    }
}
impl crate::interactive_form::InteractiveFormHooks for Foo {
    fn focused_state_idx(&self) -> Option<usize> {
        self.focused_state_idx
    }
    fn set_focused_state_idx(&mut self, idx: Option<usize>) {
        self.focused_state_idx = idx;
    }
    fn input_states_len(&self) -> usize {
        Foo::input_states_len()
    }
    #[allow(unused_variables)]
    fn input_state_at_mut(
        &mut self,
        idx: usize,
    ) -> Option<&mut dyn crate::widgets::InteractiveWidgetState> {
        if 0 == idx {
            Some(&mut self.bar)
        } else {
            if (0 + 1) == idx {
                Some(&mut self.quux)
            } else {
                if ((0 + 1) + 1) == idx {
                    Some(&mut self.whup)
                } else {
                    None
                }
            }
        }
    }
}