initial implementation and test #1417

map/backup/backup.js

@@ -1,5 +1,5 @@
 //allows you to backup and restore a map instance
-steal('can/util', 'can/map', 'can/util/object', function (can) {
+steal('can/util', 'can/compute', 'can/map', 'can/util/object', function (can) {
 	var flatProps = function (a, cur) {
 		var obj = {};
 		for (var prop in a) {
@@ -11,19 +11,26 @@ steal('can/util', 'can/map', 'can/util/object', function (can) {
 		}
 		return obj;
 	};
+
+	var oldSetup = can.Map.prototype.setup;
+
 	can.extend(can.Map.prototype, {
+		setup: function() {
+			this._backupStore = can.compute();
+			return oldSetup.apply(this, arguments);
+		},
 
 		backup: function () {
-			this._backupStore = this._attrs();
+			this._backupStore(this.attr());
 			return this;
 		},
 		isDirty: function (checkAssociations) {
-			return this._backupStore && !can.Object.same(this._attrs(), this._backupStore, undefined, undefined, undefined, !! checkAssociations);
+			return this._backupStore() && !can.Object.same(this.attr(), this._backupStore(), undefined, undefined, undefined, !! checkAssociations);
 		},
 		restore: function (restoreAssociations) {
-			var props = restoreAssociations ? this._backupStore : flatProps(this._backupStore, this);
+			var props = restoreAssociations ? this._backupStore() : flatProps(this._backupStore(), this);
 			if (this.isDirty(restoreAssociations)) {
-				this._attrs(props, true);
+				this.attr(props, true);
 			}
 			return this;
 		}

map/backup/backup_test.js

@@ -94,4 +94,25 @@ steal("can/map/backup", "can/model", "can/test", function () {
 		map.restore();
 		ok(!map.attr('foo'), 'there is no foo property');
 	});
+
+	test('isDirty wrapped in a compute should trigger changes #1417', function() {
+		expect(2);
+		var recipe = new Recipe({
+			name: 'bread'
+		});
+
+		recipe.backup();
+
+		var c = can.compute(function() {
+			return recipe.isDirty();
+		});
+
+		ok(!c(), 'isDirty is false');
+
+		c.bind('change', function() {
+			ok(c(), 'isDirty is true and a change has occurred');
+		});
+
+		recipe.attr('name', 'cheese');
+	});
 });