Easily use composition to build Backbone object prototypes

backbonePrototypeExtender.coffee

extendPrototypeFromArray = (protoConstructor) ->
  _.wrap protoConstructor.extend, (cachedExtend, mixinArray, prototype) ->
    if mixinArray instanceof Array
      # Uses _.defaults so base object overrides anything being added
      fullProto = _.defaults.apply _, [prototype].concat(mixinArray)
    else
      fullProto = mixinArray
    cachedExtend.call @, fullProto
    
Backbone.Model.extend = extendPrototypeFromArray Backbone.Model
Backbone.Collection.extend = extendPrototypeFromArray Backbone.Collection
Backbone.Router.extend = extendPrototypeFromArray Backbone.Router
Backbone.View.extend = extendPrototypeFromArray Backbone.View

exampleViewUsage.coffee

NewView = Backbone.Model.extend [ViewLogging, ViewSyncing],
  el: '.view'
  
  events:
    'click .title': 'logIt'
    'click .a': 'setA'

# This will produce the equivalent to:
# NewView = Backbone.Model.extend
#   el: '.view'
#  
#   events:
#     'click .title': 'logIt'
#     'click .a': 'setA'
#    
#   logIt: ->
#     console.log 'logged it'
#    
#   setA: ->
#     @model.set
#       a: 'a'
  

viewLogging.coffee

ViewLogging =
  logIt: ->
    console.log 'logged it'

viewSyncing.coffee

ViewSyncing =
  setA: ->
    @model.set
      a: 'a'