Re: Question about library-level functions

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

"AdaMagica" <christ-usch.grein@t-online.de> wrote in message 
news:a7a82a85-48e4-4ded-b090-06f62bd3b0b6@googlegroups.com...
...
>Creating via anonymous access is evil - how can ou ever deallocate it? This 
>should be verboten by the language.

A few too many words here: "anonymous access is evil" would have been 
enough. (At least for access-to-object.) The rules for accessibility (and 
thus finalization) are impossible to understand and typically require 
dynamic checks. Dynamic accessibility checks are surely evil, as they add 
overhead, create a "tripping hazard" (some uses are OK, others fail at 
runtime, which is not indicated by the specification), and only detect a 
minority of problems (most real uses have to resort to 'Unchecked_Access 
anyway).

These types were a mistake in Ada 95 and expanding their use compounded the 
mistake. Too bad it wasn't obvious from the beginning.

Vis-a-vis your original comment -- Ada 2012 at least gives restrictions that 
let users self-impose what the language does not:
   pragma Restrictions (No_Anonymous_Allocators); -- H.4(8.1/3)
   pragma Restrictions (No_Coextensions); -- H.4(8.2/3)
   pragma Restrictions (No_Access_Parameter_Allocators); -- H.4(8.3/3)

Can't make these the default for compatibility reasons, of course.

                                            Randy.