pub type FnGridObject = fn (mut object GridObject)

@[flag]
pub enum GridObjectAuto {
    drag
    drop
    scale_on_hover
    pickup
    sound
    off // auto "deactivation"
}

@[params]
pub struct GridObjectConfig {
    auto GridObjectAuto = ~GridObjectAuto.zero()
    on   ?FnGridObject
}

@[heap]
struct GridObject {
mut:
    config GridObjectConfig
    auto   GridObjectAuto = ~GridObjectAuto.zero()
}

pub fn on(config GridObjectConfig) &GridObject {
    mut ob := &GridObject{}
    ob.config = config
    ob.auto = config.auto
    if func := ob.config.on {
        func(mut ob)
    }
    return ob
}

fn test_main() {
    _ := on(
        on: fn (mut o GridObject) {
            o.auto = .off | .pickup | .sound
        }
    )
    assert true
}