prototypal coffee

clone.coffee

# for CoffeeScript 0.9.3

@clone = (it, mixes...) ->
  i = new (clone.r it)
  i.__proto__ ||= it
  for mix in mixes
    if typeof mix is 'function'
      mix.call i, it, i
    else
      for k, v of mix then i[k] = v
  i

@clone.r = (it) ->
  (f = ->).prototype = it
  f

@clone.p = (it, that) ->
  n = 1
  while it = it.__proto__
    return n if it is that
    ++n
  0

###
bird = wing: on, fly: -> @wing
wingless = wing: off

duck = clone bird
dodo = clone bird, wingless, extinct: yes
donaldo = clone duck, wingless, domestic: yes

ng = (bad) -> throw Error() if bad
ok = (gud) -> ng not gud

ok duck.fly()
ng donaldo.fly()
ok clone.p dodo, bird
ng clone.p dodo, wingless
ok donaldo instanceof clone.r bird