Re: Making sense of predicates

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Mon, 21 Oct 2013 23:35:59 -0500, Randy Brukardt wrote:

> It should be one step (only). We'd need something like co-derivation for 
> that, which might make sense to pursue someday (the main reason would be to 
> get rid of access types altogether, but to do that you need some sort of 
> handle, like the container cursor -- and clearly you need to be able to 
> derive the container and its handle together). But that would be a big job 
> to define properly, it would take the existing inheritance rules and make 
> them much more complex. (There are already 3 pages of rules associated with 
> inheritance for derived types.)

It is not only access types. It is relationships between types: Pointer -
Target, Array - Index - Element, etc.

If you try, as Ada designers keep on doing, to handle that at the language
level for each built-in type individually, you indeed end up with something
as horrific as accessibility rules are. That does not work.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de