define_method in coffeescript

define_method.coffee

class ContentItem
  constructor: (@type) ->

  # implementation of ruby's
  # `define_method`; simplifies
  # metaprogramming/adding methods at runtime
  @define_method: (name, fn) ->
    # syntax shorthand for
    # this.prototype[name] = function(/* arguments */){...}
    # note that `fn` will be in instance context (bound)
    @::[name] = (args...) -> fn.apply(@, args)

  for t in ['book', 'article', 'list']
    do (t) -> @define_method "is_#{t}", -> (@type is t)