1 (in-package :lisp-on-lines
)
7 (deflayer display-layer
)
9 (define-layered-function display-using-description
(description display object
&rest args
)
11 "Displays OBJECT via description using/in/with/on display"))
13 (defun display (display object
&rest args
)
14 (display-using-description (description-of object
) display object args
))
16 (define-layered-method display-using-description
17 :around
(description display object
&rest args
)
18 (declare (ignorable args
))
19 (let ((*description
* description
)
27 (define-layered-method display-using-description
(description display object
&rest args
)
28 (error "No DISPLAY-USING-DESCRIPTION methods are specified for: ~% DESCRIPTION: ~A ~% DISPLAY: ~A ~% OBJECT: ~A ~% ARGS: ~S
30 OMGWTF! If you didn't do this, it's a bug!" description display object args
))
34 (defmacro define-display
(&body body
)
35 (loop with in-descriptionp
= (eq (car body
) :in-description
)
36 with description
= (if in-descriptionp
(cadr body
) 't
)
37 for tail on
(if in-descriptionp
(cddr body
) body
)
38 until
(listp (car tail
))
39 collect
(car tail
) into qualifiers
41 (when (member :in-description qualifiers
)
42 (error "Incorrect occurrence of :in-description in defdisplay. Must occur before qualifiers."))
44 (destructuring-bind (description-spec &optional
(display-spec (gensym)) (object-spec (gensym)))
46 `(define-layered-method
47 display-using-description
48 :in-layer
,(if (eq t description
)
50 (defining-description description
))
52 (,(if (listp description-spec
)
53 (list (first description-spec
)
54 (if (eq 'description
(second description-spec
))
56 (defining-description (second description-spec
)))))
58 ,object-spec
&rest args
)
59 (declare (ignorable args
))