Re: Class-wide types algebra

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

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:nsnsho$6om$1@gioia.aioe.org...
> On 2016-10-01 07:47, Randy Brukardt wrote:
...
>> We're talking about the type that both publically and privately 
>> implements
>> the same interface.
>
> In the example provided it is P1.Child_1.T2.
>
>> (The private one inherited from the parent, the public
>> one directly added.) And we're talking about a conversion that occurs 
>> where
>> the private interface is visible (so *both* copies of the interface are
>> visible).
>
> What converted to the type? But it is irrelevant anyway. The interface 
> instances were already visible in the private part of the package where 
> the offending type was declared. The conflict was *already* resolved 
> there, or the type declaration rejected.

I need to write out the entire example to get a sensible answer from you. I 
unfortunately don't have time, as I have to get the agenda ready for the ARG 
meeting that starts on Saturday (and of course I'll be traveling all day 
Friday). So I'm going to have to drop this discussion. (So I didn't read 
your reply, sorry.)

The problem eventually becomes a run-time problem, since type conversions 
are primarily runtime artifacts. That's very ugly.

And you can't reject the declaration that has two distinct copies of the 
same interface, because that would clearly violate privacy. So you get into 
a situation where you have to chose between two copies of an interface, with 
identical names, at runtime, presumably based on visibility. That's not 
going to work.

                                           Randy.

P.S. Dmitry, Don't bother answering, I'm not going to read it or answer. 
Just can't afford the time. Sorry.