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August 9, 2020 20:04
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#lang racket | |
(define the-key 'the-key) | |
(define the-spell-book 'the-spell-book) | |
(define person% | |
(class object% | |
(init-field items h) | |
(super-new) | |
(define/public (has-item item) | |
(member item items)) | |
(define/public (height) | |
h) | |
)) | |
(define door<%> (interface () can-open can-pass)) | |
(define door-mixin | |
(mixin () (door<%>) | |
(super-new) | |
(define/public (can-open p) | |
(println "door% can-open") | |
#t) | |
(define/public (can-pass p) | |
(println "door% can-pass") | |
#t) | |
)) | |
(define secure-door<%> (interface (door<%>) needed-item)) | |
(define secure-mixin | |
(mixin (door<%>) (secure-door<%>) | |
(super-new) | |
(define/public (needed-item) ;; error?? | |
(println "secure-mixin needed-item") | |
#f) | |
(define/override (can-open p) | |
(println "secure-mixin can-open") | |
(define item (needed-item)) | |
(cond | |
((not (send p has-item item)) (printf "You don't have the Key ~v\n" item) | |
#f) | |
(else (printf "Using Key... ~v\n" item) | |
(super can-open p)))) | |
)) | |
(define locked-needed-mixin | |
(mixin (secure-door<%>) (secure-door<%>) | |
(super-new) | |
(define/override (needed-item) | |
(println "locked-needed-mixin neededItem") | |
the-key) | |
)) | |
(define magic-needed-mixin | |
(mixin (secure-door<%>) (secure-door<%>) | |
(super-new) | |
(define/override (needed-item) | |
(println "magic-needed-mixin neededItem") | |
the-spell-book) | |
)) | |
(define door% | |
(door-mixin object%)) | |
(define locked-mixin (compose locked-needed-mixin secure-mixin)) | |
(define magic-mixin (compose magic-needed-mixin secure-mixin)) | |
(define locked-magic-mixin (compose locked-mixin magic-mixin)) | |
(define locked-magic-door% (locked-magic-mixin door%)) | |
(define door (new locked-magic-door%)) | |
(send door can-open (new person% [items (list the-key the-spell-book)] [h 0.5])) | |
; class*: superclass already contains method | |
; superclass: #<class:...agic-door-failed.rkt:62:2> | |
; method name: needed-item | |
; class name: ...agic-door-failed.rkt:36:2 |
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