An extension to oath that would simplify creating/returning/passing promises.

promises.js

function promises(func) {
	var promiseIndex = func.length - 1;

	return function() {
		var scope = this;
		var args = Array.prototype.slice.call(arguments);
		var promise = args[promiseIndex] = args[promiseIndex] || new oath();

		process.nextTick(function() {
			func.apply(scope, args);
		});
		
		return promise.promise || promise;
	};
}

// -------------------------------------------------------------

// Define a function as one that uses a promise. The promise will be created
// if not given when the function is called, and automatically returned
var doFoo = promises(function(promise) {
	doSomething(function(err, results) {
		if (err) {
			return promise.reject(err);
		}

		promise.resolve(results);
	});
});

// Promise created and returned automatically
doFoo().then(...);

// Passing in your own promise, possibily from somewhere else
doFoo(new oath()).then(...);