emberjs/ember.js — pull request #3762 by southpolesteve (2013-11-19 02:31:50+00:00)
Title: Create Ember.Trackable mixin. Allows for tracking history of a property

Found this mixin very useful on a project today. Can see myself using it a lot in the future and it seemed general enough that it could be worthy of merging in upstream.

Discussion I started on the forums:
http://discuss.emberjs.com/t/trackablemixin/3385/3

Happy to discuss in more detail here or answer any questions