The choice of whether to use WITH-SLOTS versus WITH-ACCESSORS is the same as the choice between SLOT-VALUE and an accessor function: low-level code that provides the basic functionality of a class may use SLOT-VALUE or WITH-SLOTS to directly manipulate slots in ways not supported by accessor functions or to explicitly avoid the effects of auxiliary methods that may have been defined on the accessor functions. WITH-SLOTS provides direct access to the slots, as if by SLOT-VALUE, while WITH-ACCESSORS provides a shorthand for accessor methods. The form of WITH-ACCESSORS is the same as WITH-SLOTS except each element of the slot list is a two-item list containing a variable name and the name of an accessor function. However, :class slots are accessed the same as :instance slots--they're accessed with SLOT-VALUE or an accessor function, which means you can access the slot value only through an instance of the class even though it isn't actually stored in the instance.
