A C#-like dispose pattern implemented in javascript - with underscorejs and qunit. Testable: http://jsfiddle.net/52CnZ/14/

Disposable.js

!function(root, _, undefined) {

	var Disposable = root.Disposable = function() {
		this.disposed = false;
	};
	Disposable.prototype = {
		_dispose: function() {
			if (!this.disposed) {
				this.dispose();
				this.disposed = true;
			}
		},
		dispose: function() {}
	};
	
	var using = root.using = function(context, disposable, action) {
		if (arguments.length === 2) {
			action = disposable;
			disposable = context;
		}

		if (!_.isFunction(action))
			throw "No delegate specified for disposable instance.";

		if (!disposable["_dispose"])
			throw "Instance is not disposable.";

		try {
			action.apply(context, [disposable]);
		} finally {
			disposable._dispose();
		}
	};

}(this, _);

DisposableAction.js

!function(root, _, undefined) {
	
	var DisposableAction = root.DisposableAction = function(action) {
		if (!_.isFunction(action))
			throw "Specified action is not a function";

		this.action = action;
	};
	_.extend(DisposableAction.prototype, Disposable.prototype, {
		dispose: function() {
			this.action.call(this);
		}
	});

}(this, _);

DisposableTests.js

module("using");
test("Disposable pattern ensures delegate action is called with no error", function() {
	expect(2);

	using (
		new DisposableAction(function() { ok(true); }), 
		function(da) { ok(true); }
	);
});
test("Disposable pattern ensures delegate action is called with error", function() {
	expect(2);

	using (
		new DisposableAction(function() { ok(true); }), 
		function(da) { throws(function() { throw "An error has occured here."; }); }
	);
});