Multiple inheritance in Coffeescript. This little helper make proper prototype chain and call `super`. Existing classes in chain not violated, uses theirs "projections". Мультинаследование в Coffeescript. Этот маленький хелпер создаёт корректную цепочку прототипов с правильным вызовом `super`. Существующие классы не портятся, используются их "пр…

virtual_class.coffee

virtual_class = (classes...)->
  classes.reduceRight (Parent, Child)->
    class Child_Projection extends Parent
      constructor: ->
        # Temporary replace Child.__super__ and call original `constructor`
        child_super = Child.__super__
        Child.__super__ = Child_Projection.__super__
        Child.apply @, arguments
        Child.__super__ = child_super

        # If Child.__super__ not exists, manually call parent `constructor`
        unless child_super?
          super

    # Mixin prototype properties, except `constructor`
    for own key  of Child::
      if Child::[key] isnt Child
        Child_Projection::[key] = Child::[key]

    # Mixin static properties, except `__super__`
    for own key  of Child
      if Child[key] isnt Object.getPrototypeOf(Child::)
        Child_Projection[key] = Child[key]

    Child_Projection
    

Example of use:

class My extends virtual_class A, B, C

I made some tests for this library.
Child class doesnt contain any of parent.prototype variables. Also inheritance works well only for last virtual_class argument. Here you can see some tests i made https://github.com/Snowshield/mixins.coffee