Can't save LuaFunction

[rise0chen]

struct Uart<'lua> {
    on_message: LuaFunction<'lua>,
}
impl<'lua> LuaUserData for Uart<'lua> {}


    let exports = lua.create_table()?;
    lua.create_userdata(Uart {
        on_message: lua.create_function(|_, msg: String| Ok(()))?,
    });

    pub fn create_userdata<T>(&self, data: T) -> Result<AnyUserData>
    where
        T: 'static + MaybeSend + UserData,
    {
        unsafe { self.make_userdata(UserDataCell::new(data)) }
    }

I think, create_userdata just need 'lua. Why require 'static?

[khvzak]

UserData needs 'static due to TypeId::of::<T> requirements.
TypeId is used for generating and attaching shared metatable to UserData.

As an alternative, you could use Scope::create_nonstatic_userdata, it does not have 'static requirements and as a tradeoff uses unique metatable per instance (which is less efficient).

[rise0chen]

let uart = lua.scope(|scope| {
    scope.create_nonstatic_userdata(Uart {
        on_message: lua.create_function(|_, msg: String| Ok(()))?,
    })
})?;

pub fn scope<'lua, 'scope, R, F>(&'lua self, f: F) -> Result<R>
where
    'lua: 'scope,
    R: 'static,
    F: FnOnce<(&Scope<'lua, 'scope>,), Output = Result<R>>,

Oh no, Result<R>> require 'static.

[khvzak]

This is how Scope works - it drops scoped objects on function leave.

1. You could place logic inside Scope
2. Or alternatively store Lua objects in Registry using Lua::create_registry_value and keep RegistryKey which is 'static
   You can retrieve values back using Lua::registry_value

[rise0chen]

thanks, it's perfect