RosettaCodeData/Task/Call-an-object-method/LFE/call-an-object-method-1.lfe

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(defmodule aquarium
(export all))
(defun fish-class (species)
"
This is the constructor that will be used most often, only requiring that
one pass a 'species' string.
When the children are not defined, simply use an empty list.
"
(fish-class species ()))
(defun fish-class (species children)
"
This contructor is mostly useful as a way of abstracting out the id
generation from the larger constructor. Nothing else uses fish-class/2
besides fish-class/1, so it's not strictly necessary.
When the id isn't know, generate one.
"
(let* (((binary (id (size 128))) (: crypto rand_bytes 16))
(formatted-id (car
(: io_lib format
'"~32.16.0b" (list id)))))
(fish-class species children formatted-id)))
(defun fish-class (species children id)
"
This is the constructor used internally, once the children and fish id are
known.
"
(let ((move-verb '"swam"))
(lambda (method-name)
(case method-name
('id
(lambda (self) id))
('species
(lambda (self) species))
('children
(lambda (self) children))
('info
(lambda (self)
(: io format
'"id: ~p~nspecies: ~p~nchildren: ~p~n"
(list (get-id self)
(get-species self)
(get-children self)))))
('move
(lambda (self distance)
(: io format
'"The ~s ~s ~p feet!~n"
(list species move-verb distance))))
('reproduce
(lambda (self)
(let* ((child (fish-class species))
(child-id (get-id child))
(children-ids (: lists append
(list children (list child-id))))
(parent-id (get-id self))
(parent (fish-class species children-ids parent-id)))
(list parent child))))
('children-count
(lambda (self)
(: erlang length children)))))))
(defun get-method (object method-name)
"
This is a generic function, used to call into the given object (class
instance).
"
(funcall object method-name))
; define object methods
(defun get-id (object)
(funcall (get-method object 'id) object))
(defun get-species (object)
(funcall (get-method object 'species) object))
(defun get-info (object)
(funcall (get-method object 'info) object))
(defun move (object distance)
(funcall (get-method object 'move) object distance))
(defun reproduce (object)
(funcall (get-method object 'reproduce) object))
(defun get-children (object)
(funcall (get-method object 'children) object))
(defun get-children-count (object)
(funcall (get-method object 'children-count) object))