Re: Access to procedures

[tmoran@bix.com]

>>   procedure Do_Unzip is
>>       Feedback1 : feedback_handlers.My_feedback;
>> ....
>>           whatever.Extract(zi, Argument(i), method, Feedback1 );
>In that precise context, I want to avoid making this
>small unzip library depend even on the _existence_
>of all that feedbacks because an intended
>usage is a complete "invisible" unpacking, allowing
>programs to load data from a zipped one.
  Why not make the feedback parameter to Extract have a default
expression?  The default tagged object, defined in the package
defining Extract, can have no-op's for its Proc.  Then if
someone doesn't use it, or doesn't even know it exists, fine.
             whatever.Extract(zi, Argument(i), method);

>The "unrestricted_access" way seems much more simple,
>though - it seems - only provided by GNAT presently.
  The access restrictions, as previously pointed out, are there
for a reason.  IMHO, if you use "unrestricted_access", you are
living dangerously and creating a potential trap for future,
less careful, users of your Extract package.  Not to mention it
becomes non-standard Ada, tied to one particular compiler.