Re: Implicit dereferences rational question

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

"Victor Porton" <porton@narod.ru> wrote in message 
news:llb1aa$gth$1@speranza.aioe.org...
> Robert A Duff wrote:
>> Victor Porton <porton@narod.ru> writes:
>>
>>> Why implicit dereferences use only access discriminants, not arbitrary
>>> access fields?
>>
>> It helps prevent dangling pointers.
>
> In which way limiting to discriminants may prevent dangling pointers?

Discriminants have a lengthy set of accessibility rules, which turn out to 
be exactly what's needed for limiting dangling pointers. In particular, it's 
almost never the case that one can make a copy of an access discriminant, 
while that's easy for a "arbitrary access field".

                                        Randy.