The role argument is a single-valued relation, or the name of such a relation.
If the asserted-p argument is t, then the filler of role is returned only if it was explicitly asserted to fill that role. A default filler, inferred filler, or filler of a subrole of role is not returned.
The context argument is the context, or the symbol or string that names the context, where the lookup of instance and role begins. This defaults to the current context.
If the no-error-p argument is t, then error messages are suppressed.
(defrelation r :characteristics :single-valued) (defrelation s :is-primitive r :characteristics :single-valued) (set-value 'Joe 's 'Sue) (get-value 'Joe 'r) ==> |I|SUE (get-value 'Joe 'r :asserted-p t) ==> NIL (set-value 'Joe 's '(3 4 5)) (get-value (fi Joe) (fr s) :context "CL-USER-THEORY") ==> (3 4 5) (defrelation ss) (set-values 'Joe 'ss '(3 4 5)) (get-value 'Joe 'ss :no-error-p t) ==> 3 (get-value 'Joe 'xx :no-error-p t) ==> NIL :MISSING-ROLE