either the name of the class, as a string, or an object from the class.
VALUE:
slotNames() returns the character vector of the names of the slots in
the representation of class
x, if a string is given, or of
x
otherwise. With the same interpretation of its argument,
getSlots()
returns a named character vector, whose elements are the classes of the slots.
names(getSlots(x))
is equivalent to
slotNames(x).