Make options object prototype-inherited

Fixes #2294

spec/suites/core/ClassSpec.js

@@ -99,12 +99,22 @@ describe("Class", function () {
 			});
 
 			var a = new KlassWithOptions2();
+			expect(a.options.foo1).to.eql(1);
+			expect(a.options.foo2).to.eql(3);
+			expect(a.options.foo3).to.eql(4);
+		});
 
-			expect(a.options).to.eql({
-				foo1: 1,
-				foo2: 3,
-				foo3: 4
-			});
+		it("gives new classes a distinct options object", function () {
+			var K1 = L.Class.extend({options: {}});
+			var K2 = K1.extend({});
+			expect(K2.prototype.options).not.to.equal(K1.prototype.options);
+		});
+
+		it("inherits options prototypally", function () {
+			var K1 = L.Class.extend({options: {}});
+			var K2 = K1.extend({options: {}});
+			K1.prototype.options.foo = 'bar';
+			expect(K2.prototype.options.foo).to.eql('bar');
 		});
 
 		it("adds constructor hooks correctly", function () {

spec/suites/core/UtilSpec.js

@@ -185,7 +185,47 @@ describe('Util', function () {
 		});
 	});
 
-	// TODO setOptions
+	describe('#setOptions', function () {
+		it('sets specified options on object', function () {
+			var o = {};
+			L.Util.setOptions(o, {foo: 'bar'});
+			expect(o.options.foo).to.eql('bar');
+		});
+
+		it('returns options', function () {
+			var o = {};
+			var r = L.Util.setOptions(o, {foo: 'bar'});
+			expect(r).to.equal(o.options);
+		});
+
+		it('accepts undefined', function () {
+			var o = {};
+			L.Util.setOptions(o, undefined);
+			expect(o.options).to.eql({});
+		});
+
+		it('creates a distinct options object', function () {
+			var opts = {},
+				o = L.Util.create({options: opts});
+			L.Util.setOptions(o, {});
+			expect(o.options).not.to.equal(opts);
+		});
+
+		it("doesn't create a distinct options object if object already has own options", function () {
+			var opts = {},
+				o = {options: opts};
+			L.Util.setOptions(o, {});
+			expect(o.options).to.equal(opts);
+		});
+
+		it('inherits options prototypally', function () {
+			var opts = {},
+				o = L.Util.create({options: opts});
+			L.Util.setOptions(o, {});
+			opts.foo = 'bar';
+			expect(o.options.foo).to.eql('bar');
+		});
+	});
 
 	describe('#template', function () {
 		it('evaluates templates with a given data object', function () {

src/core/Class.js

@@ -50,8 +50,8 @@ L.Class.extend = function (props) {
 	}
 
 	// merge options
-	if (props.options && proto.options) {
-		props.options = L.extend({}, proto.options, props.options);
+	if (proto.options) {
+		props.options = L.Util.extend(L.Util.create(proto.options), props.options);
 	}
 
 	// mix given properties into the prototype

src/core/Util.js

@@ -18,6 +18,14 @@ L.Util = {
 		return dest;
 	},
 
+	create: Object.create || (function () {
+		function F() {}
+		return function (proto) {
+			F.prototype = proto;
+			return new F();
+		};
+	})(),
+
 	bind: function (fn, obj) {
 		var slice = Array.prototype.slice;
 
@@ -107,8 +115,10 @@ L.Util = {
 	},
 
 	setOptions: function (obj, options) {
-		obj.options = options ? L.extend({}, obj.options, options) : obj.options || {};
-		return obj.options;
+		if (!obj.hasOwnProperty('options')) {
+			obj.options = obj.options ? L.Util.create(obj.options) : {};
+		}
+		return L.extend(obj.options, options);
 	},
 
 	getParamString: function (obj, existingUrl, uppercase) {