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From: Egil Harald Hoevik <egil.harald.hoevik@kongsberg.com>
Newsgroups: comp.lang.ada
Subject: Re: Renaming an abstract function 
Date: Sat, 17 Nov 2001 18:47:21 +0100
Organization: Kongsberg Group ASA , Norway
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Date: 2001-11-17T18:47:21+01:00
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Adam Beneschan wrote:
> 
<snip> 
> A "callable entity" is defined (in 6(2)) to be a subprogram or entry.
> Thus an abstract subprogram is a callable entity even though you can't
> really call it.
> 

RM 6 (1): 
"...The definition of a subprogram can be given in two parts: 
a subprogram declaration defining its interface, and a subprogram_body
defining its execution..."

So, a subprogram (callable entity) requires a body (callable construct),
while an abstract subprogram does not, 
and the RM distinguishes between the two:

RM 6.1 (2-3):
   subprogram_declaration ::= subprogram_specification;
   abstract_subprogram_declaration ::= 
     subprogram_specification is abstract;



> I don't see any prohibition on renaming an abstract subprogram.
> However, renaming subprograms don't quite take on all the
> characteristics of the subprograms they rename; see 8.5.4(12) for
> instance.  I suspect that has something to do with why renaming an
> abstract subprogram could lead to an error, but I don't have time
> right this minute to look into it further.
> 
>                                 -- Adam


Well,

RM 8.5.4 (2):
  subprogram_renaming_declaration ::= 
    subprogram_specification renames callable_entity_name;

If renaming an abstract subprogram were allowed, I, 
at least, would think that the language would explicitly 
require the keyword 'abstract' in the renaming declaration 
(which it does not).



~egilhh
-- 
"What I seek is to serve, with my feeble capacity, 
truth and justice at the risk of pleasing no-one."
Albert Einstein.