Re: Suggestion: Allow functions returning abstract types in certain situations

[Robert A Duff <bobduff@shell01.TheWorld.com>]

Adam Beneschan <adambeneschan@gmail.com> writes:

> Although at first glance this appeared reasonable to me, I think
> there's a huge problem: how would you write the *body* of the
> function?  The function would have to return something.  The language
> doesn't allow you to declare objects of an abstract type, so Func
> could not declare a local variable "Result" of type T1 that it could
> return.  Nor could it return an aggregate, which involves creating a
> temporary object.

Those things would have to be allowed, too.

>...In my view, the language model depends heavily on
> the assumption that an object can never be created whose tag refers to
> an abstract type; allowing the rule to *ever* be relaxed could be
> disastrous.

I don't think so.  As I posted a while back, the only trouble comes
from converting an object of an abstract type to a class-wide
type -- that is what needs to be forbidden.

Note to the OP:  You can also use the form of extension aggregate
where you give the ancestory type name.  In that case, you get
default initialization, which is unfortunate, but it does work.

- Bob