Re: "NULL" returned by a function

[Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org>]

On 08/08/2014 02:10 PM, Victor Porton wrote:
> What if I want to make a function which returns either a value of type T or
> a value signifying "nothing" (like null pointer)?

Typically one should use a variant record with one variant for "nothing" and 
another for the value:

type Result (Has_Value : Boolean := False) is record
    case Has_Value is
    when False =>
       null;
    when True =>
       Value : T;
    end case;
end record;

-- 
Jeff Carter
"We call your door-opening request a silly thing."
Monty Python & the Holy Grail
17