Function s4_has_slot 

pub unsafe fn s4_has_slot(obj: SEXP, slot_name: &str) -> bool

Check if an S4 object has a named slot.

Attempts to access the slot via s4_get_slot. Returns true if the slot exists and is accessible, false if accessing it errors (i.e., the slot does not exist).

Safety

• obj must be a valid SEXP (typically an S4 object).
• Must be called from the R main thread.