24 lines
579 B
Plaintext
24 lines
579 B
Plaintext
(defstruct animal nil
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name
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(:method get-name (me)
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(if me.name me.name (error `get-name: animal @me has no name`)))
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(:method speak (me stream)
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(error "abstract animal cannot speak")))
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(defstruct dog animal
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(:method speak (me : (stream *stdout*))
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(put-line `@{me.(get-name)}: bark!` stream)))
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(defstruct cat animal
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(:method speak (me : (stream *stdout*))
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(put-line `@{me.(get-name)}: meow!` stream)))
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(defstruct lab dog)
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(defstruct collie dog)
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(let ((pet1 (new collie name "Lassie"))
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(pet2 (new cat name "Max")))
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pet1.(speak)
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pet2.(speak))
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