Re: child class of limited_controlled not inheriting data

[rieachus@comcast.net]

On Friday, August 5, 2016 at 2:59:16 PM UTC-4, b.mcgui...@gmail.com wrote:
> I defined a base class as
... 
>   function To_Date (days : Integer; fraction : Real) return Date;
>   function To_Date (time_string : String)            return Date;
... 
> What is wrong here?

Actually you have the solution right there, except that you will want to override To_Date for your Julian date abstraction to correct the times.  Julian dates, at least in astronomical use, begin at noon GMT.  (I could chide you for not having a timezone parameter everywhere needed, but I am going to assume that you will add that after you get the basics working. ;-)

There is a bit of magic necessary in your overriding of To_Date.  You need to call the original function:

function To_Date(days : Integer; fraction : Real) return Julian_Date is
  Jdays: Integer := days;
  Jfraction: Real := fraction;
begin
  -- fix up Jdays and Jfraction here.
  return sofa.time.two_part_date.To_Date(Jdays,Jfraction) with null;
end To_Date;

I would probably use a fixed point type, Milliseconds, instead of your Float fraction, but even if I could convince you why it is better, it probably is not worth changing, unless you are pointing a really big telescope at asteroids.