as i noted in my earlier query, delegation in lisp depends on a binding for
the referent. synonym streams effect this with a special variable.
object-based delegation can support it with a slot binding. it would be
possible to do it with closed-over variables, but i'm not acquainted with
implementation which use that technique. given this requirement, that is, that
the referent is bound somewhere, the only difference i can discern between the
special-binding-based delegation and the slot-based delegation is, well, the
nature of the binding.

if i take a tiny example. let's say i would like to generate svg. i have these
data objects which need to be serialized. in order to support delegation,
there has to be some provision for it in the api protocol.

in this case, the base generic function and default definitions are all
generated via
macros. like

(defProjectionOp line (l1 l2 &optional properties))
(defProjectionOp line*2 (x1 y1 x2 y2 &optional properties))
(defProjectionOp line*3 (x1 y1 z1 x2 y2 z2 &optional properties))

in order to provide for delegation - or whatever sort - i would think that
there has to be a definition somewhere which looks something like

(defmethod op ((instance delegate) &rest args)
  (apply #'op (delegate-referent instance) args))

are there alternatives? given that, the generation function for delegatable
operations needs an additional clause. some thing like

(push `(:method ((delegate delegate-context) ,@lambda-list)
                (,do-call #',operator-name
                     (delegate-referent delegate) ,@arguments))
      methods)

which is not that complex and provides for any class which specializes
delegate-context and implements delegate-referent. it is not material whether
the class specializes synonym-stream or some other abstract class. assuming
that the projection operations above are so defined, the alternative
delegation forms do not look very different.

(defClass svg-presenter () ()
  (:documentation
   "the protocol class which specifies the presence of the svg presentation methods"))

(defClass svg-context (aspect-context)
  ((stream
    :initform nil :initarg :stream
    :reader context-stream
    :documentation "bound to an output stream for svg-envoded output."))
  (:documentation
   "a context which implements graphics operations as svg serialization."))

(defclass svg-wrapper-context (delegate-context svg-presenter stream)
  ((context :reader effective-context :initarg :context))
  (:documentation
   "a wrapper which implements svg presentation methods through delegation to
a context which implements graphics operations."))

(defParameter *svg-output* nil)

(defClass svg-synonym-context (delegate-context svg-presenter synonym-stream)
  ()
  (:default-initargs :symbol '*svg-output*)
  (:documentation
   "a synonym context which delegates through a spacial variable binding
rather than a slot binding."))

(defMethod effective-context ((synonym-context svg-synonym-context))
  (symbol-value (synonym-stream-symbol synonym-context)))

[ ignoring the stream operations which the wrapper needs to act as a stream ]

the concrete serialization looks something like this

(defun svg-line*3 (x1 y1 z1 x2 y2 z2 &optional aspects)
  "serialize a line given the 3d location"
  #+og.assert-types (progn (assert-types (x1 y1 z1 x2 y2 z2) number)
                           (assert-type aspects sequence))
  (flet ((emit-line ()
           (xml ({svg}line ({}x1  x1) ({}y1  y1)
                           ({}x1  x2) ({}y1  y2)
                           ({}stroke *svg-stroke-color*)))))
    (declare (dynamic-extent #'emit-line))
    (call-with-aspects #'emit-line aspects)))

(defMethod .og.::line*3 ((context svg-context) x1 y1 z1 x2 y2 z2 &optional aspects)
  "draw a line given two extreme 3d vertices"
  (svg-line*3 x1 y1 z1 x2 y2 z2 aspects))

(defMethod .og.::line*2 ((context svg-context) x1 y1 x2 y2 &optional aspects)
  "draw a line given two extreme 2d vertices"
  (svg-line*3 x1 y1 0.0d0 x2 y2 0.0d0 aspects))

(defMethod .og.::line ((context svg-context) l1 l2 &optional aspects)
  "draw a line given the end locations (2-d or 3-d) in object/world coordinates"
  ;; ignoring that svg is only 2d
  (with-location-coordinates (((x1 y1 z1) l1) ((x2 y2 l2) l2))
    (svg-line*3 x1 y1 z1 x2 y2 l2 aspects)))

the projection interface looks something like this

(defgeneric present (instance context)
  (:method ((instance line) (context svg-presenter))
           (line context (location instance) (end instance)
                       (presentation-properties instance context))))

and the usage looks something like this

(defParameter *svgc* (make-instance 'svg-context :stream *trace-output*))
;(context-stream *svgc*)

(defParameter *svg-wc* (make-instance 'svg-wrapper-context :context *svgc*))
;(effective-context *svg-wc*)
;(context-stream (effective-context *svg-wc*))

(defParameter *svg-sc* (make-instance 'svg-synonym-context :symbol '*svg-output*))

(setq *svg-output* *svg-wc*)

(with-projection-context (*svgc*)
  (let ((line (make-instance 'line
                :location #@(|3| 0.0 0.0 0.0)
                :end #@(|3| 1.0 1.0 1.0))))
    (format *svg-wc* "~%~%<!-- presenting to a svg-wrapper-context: -->~%")
    (present line *svg-wc*)
    (format *svg-sc* "~%~%<!-- presenting to a svg-synonym-context: -->~%")
    (present line *svg-sc*)))

wherein i discern no difference between synonym classes and wrapper classes.
do the problems surrounding a terminal-stream-with-double-spacing a
clim:presenting-stream has a shape which is so different from this?