Re: Possible Ada deficiency?

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

On 10 Jan 2005 20:44:42 +0100, Pascal Obry wrote:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
> 
>> You mean that there is a non-Ada body. But for Import I would provide an
>> Ada body and place the pragma there (if that should be a pragma). Later one
>> could replace the body with an Ada implementation and vise versa *without*
>> touching specifications.
> 
> Ok, but it seems wrong to me to hide Export/Import. This is definitly part of
> the interface.

To me it is just an implementation.

> Reviewers/Users must know if this is imported or not.

What for? What about specifying the library version number of the imported
thing? Reviewer must rely on the contract. Linkage issues are not a
contract to me.

> Idem for
> Inline, this is really part of the spec and tells you that the code will be
> inline in yours. If you have size considerations for your code it seems quite
> important to note this just by reading the spec.

If so, then it must be a syntax like in C++ not a pragma. And the issue
here is not the code size. Because it is quite difficult to predict. The
only issue I see here is evaluation of constants at compile time. For
example:

procedure Trace (Text : String);
pragma Inline Trace;

procedure Trace (Text : String) is
begin
   if Trace_On then
      Put (Text);
   end if;
end Trace;

When Trace_On is statically False we hope the compiler will remove calls to
Trace upon inlining. In my view this issue should be controlled not by
pragmas by the contract. If that were possible in some reasonably general
way then we could do much more useful things than Trace above. We could
allow user-defined array dopes, remove statically known discriminants, have
specific object without tags.

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