macro_rules! impl_base_obj {
    ($base_name:ident, $type_name:ident) => {
        fn instantiate(&mut self) {
            let ty = $crate::obj::BUILTINS.with_borrow(|builtins| {
                builtins
                    .get(stringify!($type_name))
                    .expect(concat!("no ", stringify!($type_name)))
                    .clone()
            });
            self.set_attr("__ty__", ty);
            self.$base_name.instantiate();
        }

        fn is_instantiated(&self) -> bool {
            self.$base_name.is_instantiated()
        }

        fn attrs(&self) -> &$crate::obj::Attrs {
            self.$base_name.attrs()
        }

        fn attrs_mut(&mut self) -> &mut $crate::obj::Attrs {
            self.$base_name.attrs_mut()
        }

        fn as_any(&self) -> &dyn std::any::Any {
            self
        }

        fn as_any_mut(&mut self) -> &mut dyn std::any::Any {
            self
        }
    };
    ($type_name:ident) => {
        impl_base_obj! { base, $type_name }
    };
}

macro_rules! impl_create {
    ($($arg:ident : $ty:ty),* $(,)?) => {
        pub fn create($($arg : $ty ),*) -> $crate::obj::ObjP {
            let ptr = make_ptr(Self::new($($arg),*));
            ptr.borrow_mut().instantiate();
            ptr
        }
    }
}

pub(crate) use impl_base_obj;
pub(crate) use impl_create;