R: what are Slots?

Question

Does anyone know what a slot is in R?

I did not find the explanation of its meaning. I get a recursive definition: \"Slot function returns or set information about the

Answer 1

In addition to the resources @Joris points you to, plus his own answer, try reading ?Classes, which includes the following on slots:

 Slots:

      The data contained in an object from an S4 class is defined
      by the _slots_ in the class definition.

      Each slot in an object is a component of the object; like
      components (that is, elements) of a list, these may be
      extracted and set, using the function ‘slot()’ or more often
      the operator ‘"@"’.  However, they differ from list
      components in important ways.  First, slots can only be
      referred to by name, not by position, and there is no partial
      matching of names as with list elements.
      ....