Ember Computed Property Helpers

README.md

Ember Computed Property Helpers

More info at http://www.benlesh.com

Open license.. use however. EXCEPT THIS README, IF YOU USE THIS I'LL SUE.

computed-property-helpers.js

var GETKEY_REGEXP = /^([A-Za-z0-9$_\.]*[A-Za-z0-9$_]+)(\.@each|\.\[\])?/;

function parseArguments(args) {
	var handler = args[args.length - 1];
	var observed = [].slice.call(args, 0, args.length - 1);
	var keys = observed.map(function(name) {
      var parts = GETKEY_REGEXP.exec(name);
      if(!parts) {
        return null;
      }
      return parts[1];
    });

	return {
		handler: handler,
		observed: observed,
		keys: keys
	};
}

function shorthandFor(type) {
	return function() {
		var args = parseArguments(arguments);

		var actualHandler = function() {
			var self = this;
			return args.handler.apply(self, args.keys.map(function(key) {
				return self.get(key);
			}));
		};

		return Function.prototype[type].apply(actualHandler, args.observed);
	};
}

export var property = shorthandFor('property');
export var observer = shorthandFor('observes');

default-property-example.js

import Ember from 'ember';

export default Ember.Object.extend({
  _a: 'a',
  _b: 'b',
  _c: 'c',
  
  a: function(name, value) {
    if(arguments.length > 1) {
      this._a = value;
    }
    return this._a;
  }.property(),
  
  b: function(name, value) {
    if(arguments.length > 1) {
      this._b = value;
    }
    return this._b;
  }.property(),
  
  c: function(name, value) {
    if(arguments.length > 1) {
      this._c = value;
    }
    return this._c;
  }.property(),
  
  composite: function() {
    var a = this.get('a');
    var b = this.get('b');
    var c = this.get('c');
    return a + b + c;
  }.property('a','b','c'),
  
  _didChangeAorB: function(){
    var a = this.get('a');
    var b = this.get('b');
    console.log('a or b changed!', a, b);
  }.observes('a', 'b')
})

helper-property-example.js

import Ember from 'ember';
import { observer, property } from 'computed-property-helpers';

var alias = Ember.computed.alias;

export default Ember.Object.extend({
  _a: 'a',
  _b: 'b',
  _c: 'c',
  
  a: alias('_a'),
  b: alias('_b'),
  c: alias('_c'),
  
  composite: property('a','b','c', function(a, b, c) {
    return a + b + c;
  }),
  
  _didChangeAorB: observer('a', 'b', function(a, b) {
    console.log('a or b changed!', a, b);
  })
});