Issues with Ember

autobinding.coffee

###
# This emberjs example makes me cring for a couple reasons,
# but the biggest is that it calls `.property` on the function
# to turn fullName into a auto-updating value.
# Since emberjs is a framework instead of a library, like Backbone,
# it seems like it should do this for you.

App.Person = DS.Model.extend({
  firstName: DS.attr('string'),
  lastName: DS.attr('string'),
  fullName: function() {
    return this.get('firstName') +
           " " + this.get('lastName');
  }.property('firstName', 'lastName')
});

# We can know what `get` calls are made in that context.
# Let's just log those and updated the property value
# when a dependency is changed. I whipped up this quick
# example below.
###


#lib

_ = require 'underscore'

extend = (properties) ->
  instance = {}
  instance.attributes = {}
  getters = {}
  dependencies = []

  instance.get = (name) ->
    this.attributes[name]

  instance.set = (name, value) ->
    this.attributes[name] = value
    for attr in dependencies[name]
      this.reset(attr)

  instance.reset = (name) ->
    this.attributes[name] = getters[name].apply(instance)

  for name, func of properties
    getters[name] = func
    context = _.clone(instance)
    context.get = (attrname) ->
      dependencies[attrname] ?= []
      dependencies[attrname].push(name)
      instance.get(attrname)
    instance[name] = func.apply(context)

  instance

# setup

instance = extend
  fullName: ->
    firstName = this.get('firstName')
    lastName = this.get('lastName')
    firstName + ' ' + lastName

# test

instance.set('firstName', 'Some')
instance.set('lastName', 'Guy')

console.log instance.get('fullName') # Some Guy
instance.set('lastName', 'Girl')
console.log instance.get('fullName') # Some Girl