17 lines
419 B
Racket
17 lines
419 B
Racket
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(define (point x y)
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(define (dispatch m)
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(cond ((eq? m 'getx) x)
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((eq? m 'gety) y)
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((eq? m 'type) 'point)
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((eq? m 'info) (list 'point x y))
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(else (display (string-append "point as no method: " (symbol->string m) "\n")))))
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dispatch)
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(define p (point 1 2))
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(p 'getx) ; 1
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(p 'gety) ; 2
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(p 'type) ; point
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(p 'info) ; (point 1 2)
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(p 'foo) ; display "point as no method: foo
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