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 memcached.getAsync(key);
	    })
        }
    })
};


//Calling

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