patlama

components.to-display-computed.js

import Ember from 'ember';

export default Ember.Component.extend({
  myX: Ember.computed('item.computedX', function(){
    let result = this.get('item.computedX');    
    return result;
  }),
  myY: Ember.computed('item.computedY', function(){
    let result = this.get('item.computedY');    
    return result;
  }),
});

components.to-update-fields.js

import Ember from 'ember';
const {computed} = Ember;

let fp = Ember.Object.extend({
  d: 'd',
  /*fpX: computed.alias('component.computedProperty.x'),
  fpY: computed.alias('component.computedProperty.y'),
  fpZ: computed.alias('component.computedProperty.external'),*/
  
  fpXBinding: 'component.computedProperty.x',
  fpYBinding: 'component.computedProperty.y',
  fpZBinding: 'component.computedProperty.external',
});

export default Ember.Component.extend({
  init() {
    this._super(...arguments);
    this.set('fp', fp.create({component:this}));
  },
  
  computedProperty:Ember.computed('item.x','item.y', 'externalField', function(){
    return {'x': this.get('item.x'), 'y': this.get('item.y'),
            'external': this.get('externalField')}
  }),
  
  actions: {
    onupdateX(value) {
      this.get('item').set('x', value);
    },
    
    onupdateY(value) {
      this.get('item').set('y', value);
    },
    
    onexternalupdate(value) {
      this.set('externalField', value.z);
    }
  }
});

components.to-update-subfield.js

import Ember from 'ember';

export default Ember.Component.extend({
    computedProperty:Ember.computed('item.z', function(){
     let z = {'z': this.get('item.z')};
     	this.get('onexternalupdate')(z); 
    return z;
  }),
  
    actions: {
      onupdateZ(value) {
        this.get('item').set('z', value);
      },
    }
});

controllers.application.js

import Ember from 'ember';

let item = Ember.Object.extend({

    computedProperty: Ember.computed('x', 'y', function(){
      
      return {x: this.get('x'), y:this.get('y')}
    })
});

export default Ember.Controller.extend({
  item: item.create(),
  
  init() {
    this.set('fp', Ember.Object.create({
    	item: this.get('item'),
    	/*computedXBinding: 'item.computedProperty.x',
  		computedYBinding: 'item.computedProperty.y'*/
      computedX: Ember.computed.alias('item.computedProperty.x'),
      computedY: Ember.computed.alias('item.computedProperty.y')
  }));
  	Ember.defineProperty(this.get('item'), 'computedX', Ember.computed.alias('computedProperty.x'));
      	Ember.defineProperty(this.get('item'), 'computedY', Ember.computed.alias('computedProperty.y'));
   
	},
  
  actions: {
    computedChanged(property, value) {
    	this.set(property, value);
  	}
  }
});

templates.application.hbs

{{to-update-fields item=item}}

<br>

templates.components.to-display-computed.hbs

{{yield}}
{{myX}}--{{myY}}

templates.components.to-update-fields.hbs

<b>To update field</b>
{{fp.fpX}}-{{fp.fpY}}-{{fp.fpZ}}--{{fp.d}}
<br>
{{yield}}
<input value={{item.x}} oninput={{action 'onupdateX' value="target.value"}}>
<input value={{item.y}} oninput={{action 'onupdateY' value="target.value" }}>
<br><br>
{{to-update-subfield item=item onexternalupdate=(action 'onexternalupdate')}}

templates.components.to-update-subfield.hbs

{{yield}}
<input value={{item.z}} oninput={{action 'onupdateZ' value="target.value"}}>
{{computedProperty.z}}

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}