remember.js

Cache.remember = function (key, lifetime, callback) {
	return Promise.try(() => {
		return memcached.getAsync(key);
	}).then((value) => {
		if (value !== undefined) {
			console.log('exists');
			return value;
		} else {
			return Promise.try(() => {
				if (typeof callback === "function") {
					return callback()
				}else{
					throw new Error('callback undefined or not a function')	
				}
			}).then((value) => {
				console.log('does not exists');
				return memcached.setAsync(key, value, lifetime); 
			}).then(() => {
				return value;
			})
		}
	})
};


//Calling

		cache.remember('key', 600, function() {
			return Promise.resolve('value2');	
		}).then((val) => {
			console.log('set: ', val);
		})