Re: Will "renames" increase program size?

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

"AdaMagica" <christ-usch.grein@t-online.de> wrote in message 
news:4bdd2495-fb00-4aa7-89bd-910dfefa3704@i4g2000yqg.googlegroups.com...
>> procedure Shame is
>> type T is array (Integer range <>) of Integer;
>> A : T := (0 => 0, 1 => 1);
>> subtype S is T (1..2);
>> B : S renames A;
>> begin
>> Put_Line (Integer'Image (B (0))); -- Surprise, 0 is a legal index of S!
>> end Shame;
>
>Yes, agreed, that's annoying and confusing. Perhaps such a renaming
>should be forbidden. Don't know what other consequences such a rule
>would have, which other rules would have to be adapted. Think of
>generics... (I know you dislike generics.)

Everyone agrees that this was a mistake of Ada 83, mainly because it didn't 
have the concept of static matching. (Someone dug up the 1983 e-mail thread 
that led to this mistaken rule.) However, fixing it would be widely 
incompatible -- for instance, virtually all renames of operators would be 
illegal under a matching rule (their parameters would need to be T'Base, but 
hardly anyone actually writes that). We've looked at rules that would be 
less incompatible, but they get very complex and it just didn't seem worth 
the headaches.

We've discussed this before on comp.lang.ada (I don't recall exactly when).

                             Randy.