New Twiddle

components.test-component.js

import Ember from 'ember';

export default Ember.Component.extend({

	getlabel : Ember.computed ('item.label',function()
	{
		var item = this.get("item");
	Ember.Logger.log("getlabel",item.label);
		return item.label + " " + new Date;

	}),

});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({

	data : Ember.A([]),

	actions :
	{
		addData : function()
		{
			var data = this.get("data");

			data.addObject({label:data.length});
		},
    
    
		changeData : function()
		{
			var data = this.get("data");

			Ember.set(data[0],"label",data[0].label++);
		},
	}
});

templates.application.hbs

<button {{action 'addData'}}>Add</button>

<button {{action 'changeData'}}>Change</button>

{{#each data as |item|}}

	{{test-component item=item}}

{{/each}}

templates.components.test-component.hbs

{{getlabel}}

twiddle.json

{
  "version": "0.4.7",
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/1.13.6/ember.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/1.13.7/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/1.13.6/ember-template-compiler.js"
  }
}