CL-USER> (defclass foo () ((bar :initarg :bar) (baz :initarg :baz) (quux :initarg :quux))) # CL-USER> (defparameter *foo* (make-instance 'foo :bar :bar :baz :baz :quux :quux)) *FOO* CL-USER> (sb-mop:standard-instance-access *foo* 0) :BAR CL-USER> (sb-mop:standard-instance-access *foo* 1) :BAZ CL-USER> (sb-mop:standard-instance-access *foo* 2) :QUUX CL-USER> (defclass foo () ((baz :initarg :baz) (quux :initarg :quux) (bar :initarg :bar))) # CL-USER> (sb-mop:standard-instance-access *foo* 0) :BAR CL-USER> (sb-mop:standard-instance-access *foo* 1) :BAZ CL-USER> (sb-mop:standard-instance-access *foo* 2) :QUUX CL-USER> (slot-value *foo* 'baz) :BAZ CL-USER> (sb-mop:standard-instance-access *foo* 0) :BAZ CL-USER> (sb-mop:standard-instance-access *foo* 1) :QUUX CL-USER> (sb-mop:standard-instance-access *foo* 2) :BAR