It's often necessary to create a Date from other arguments than a string .  Should have fromTicks(uint ticks) - and in fact consequent on that, now(), and fromDateParts(int year, int month ....) - if you are getting the numbers from somewhere else.

All the from... methods should set weekday and there should be a yday (day of year) member that all the population methods should set.

I have coded this because I needed it, if of interest see www.britseyeview.com/D/