Function sidecar_set 

#[doc(hidden)]
pub fn sidecar_set<O, T>(
    ptr: &mut impl SidecarOwnerMut<O>,
    index: usize,
    name: &'static str,
    field: fn(&O) -> &Sidecar<T>,
    value: T,
)
where
    O: TypedExternal,
    T: IntoR,

Stores value in T’s Sidecar field index of the object ptr holds, dropping the field’s pending value, which this write supersedes.

Called by the setters #[derive(ExternalPtr)] generates (T::set_field(&mut ptr, value)); field selects the struct’s Sidecar field.

Panics

Off R’s main thread, naming the field, before touching R.