Re: Is there a reason System.Storage_Pools isn't Pure?

[Shark8 <onewingedshark@gmail.com>]

On Friday, April 21, 2017 at 11:02:52 PM UTC-6, Randy Brukardt wrote:
> "Shark8" wrote in message 
> news:a498c0f6-11ae-4050-ade0-bc35c686dc1c...
> > On Wednesday, April 19, 2017 at 2:36:28 PM UTC-6, Randy Brukardt wrote:
> >>
> >> Your spec here doesn't have any way to put an element into the holder. 
> >> And
> >> that's where the trouble comes (especially for limited types!). Perhaps 
> >> you
> >> can figure it out (I haven't been able to). As it stands, your holder
> >> objects would have to have Has_Element = False. Not very useful. ;-)
> >
> > I should have known better than to type it on-the-fly.
> > Here's a different spec that actually does compile under GNAT, even though 
> > [AFACT] it shouldn't:
> 
> Right; it contains an assignment of a limited private type, which is, ummm, 
> surprising. :-)

For Replace_Element?
There's no assignment of a limited private type there, it's an assignment replacing the whole parameter "container", which is in this case an access type.
(Or do you mean in To_Holder?)

> 
> You probably could use a constructor allocator to do that in limited (pun 
> not intended) cases, but that would be a new object which couldn't exist 
> outside of the container. Might be useful in some cases...

Sounds like a good way to (e.g.) bind a value to a particular storage [sub]pool, IIUC.