Re: Virtual Components in Ada and Ruby

["Randy Brukardt" <randy@rrsoftware.com>]

"Frank J. Lhota" <NOSPAM.lhota@adarose.com> wrote in message
news:2ifue.819$Z97.597@trndny06...
....
> Looking ahead to Ada 201Z, should there be user-defined virtual record
> components? Currently, a component of a record must always be defined as
> a section of memory in a record. Would it be desirable to also be able
> to define a record component in terms of subprograms for reading and
> writing that component?

I think it would likely be too ambiguous with other possibilities to be very
useful.

Certainly, Ada 200Y has "virtual record components" for reading:

    type Something is tagged record ... end record;
    function Virtual (Obj : in Somthing) return Integer;

    Object : Something;

    if Object.Virtual = 10 then ...

But there doesn't seem to be a practical way to make them writable on the
LHS of an assignment. A procedure call isn't too bad in that case:
    Object.Set_Virtual (To => <args>);

                            Randy.