Inheritance/Single: Difference between revisions

====Inheritance among symbolic exception tags====

====OOP Inheritance in TXR Lisp====

<lang txr>(defstruct animal nil

name

(get-name

(lambda (me)

(if me.name me.name (error `get-name: animal @me has no name`))))

(speak

(lambda (me stream)

(error "abstract animal cannot speak"))))

(defstruct dog animal

(speak

(lambda (me : (stream *stdout*))

(put-line `@{me.(get-name)}: bark!` stream))))

(defstruct cat animal

(speak (lambda (me : (stream *stdout*))

(put-line `@{me.(get-name)}: meow!` stream))))

(defstruct lab dog)

(defstruct collie dog)

(let ((pet1 (new collie name "Lassie"))

(pet2 (new cat name "Max")))

pet1.(speak)

pet2.(speak))</lang>

{{out}}

<pre>Lassie: bark!

Max: meow!</pre>