Question: dynamic rename?

Question: dynamic rename?

[Darkwing]

Is there an Ada elegant way to do something like the following:

signal : signal_type renames =>
case configuration is
 when one => signal_one;
 when two => signal_two;
end case;

Re: Question: dynamic rename?

[Dmitry A. Kazakov]

On Fri, 2 Sep 2011 19:28:38 -0700 (PDT), Darkwing wrote:

> Is there an Ada elegant way to do something like the following:
> 
> signal : signal_type renames =>
> case configuration is
>  when one => signal_one;
>  when two => signal_two;
> end case;

Nested subprogram taking signal as an argument.

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

Re: Question: dynamic rename?

[Simon Wright]

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> On Fri, 2 Sep 2011 19:28:38 -0700 (PDT), Darkwing wrote:
>
>> Is there an Ada elegant way to do something like the following:
>> 
>> signal : signal_type renames =>
>> case configuration is
>>  when one => signal_one;
>>  when two => signal_two;
>> end case;
>
> Nested subprogram taking signal as an argument.

I thought that, but what if signal_one, signal_two were variables and
you needed an lvalue? I think you'd need to return an access value. Must
depend very much on context.

Re: Question: dynamic rename?

[Dmitry A. Kazakov]

On Sat, 03 Sep 2011 11:04:05 +0100, Simon Wright wrote:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
> 
>> On Fri, 2 Sep 2011 19:28:38 -0700 (PDT), Darkwing wrote:
>>
>>> Is there an Ada elegant way to do something like the following:
>>> 
>>> signal : signal_type renames =>
>>> case configuration is
>>>  when one => signal_one;
>>>  when two => signal_two;
>>> end case;
>>
>> Nested subprogram taking signal as an argument.
> 
> I thought that, but what if signal_one, signal_two were variables and
> you needed an lvalue?

declare
   procedure Do_Things (Signal : in out Signal_Type) is
   begin
       ...
   end Do_Things;
begin
   case Configuration is
     when one =>
         Do_Things (Signal_one);
     when two =>
         Do_Things (Signal_two);
   end case;
   ...
?

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

Re: Question: dynamic rename?

[ytomino]

If signal_one and signal_two are (aliased) variable,

function signal_ref return access signal_type is
begin
   case configuration is
      when one => return signal_one'Access;
      when two => return signal_two'Access;
   end case;
end signal_ref;

signal : signal_type renames signal_ref.all;

Re: Question: dynamic rename?

[Pascal Obry]

Le 03/09/2011 14:27, ytomino a �crit :
> If signal_one and signal_two are (aliased) variable,
>
> function signal_ref return access signal_type is
> begin
>     case configuration is
>        when one =>  return signal_one'Access;
>        when two =>  return signal_two'Access;
>     end case;
> end signal_ref;
>
> signal : signal_type renames signal_ref.all;

Or using a case expression in Ada 2012:

    Signal : Signal_Type :=
               (case Configuration is
                   when One => Signal_One,
                   when Two => Signal_Two);

Pascal.

-- 

--|------------------------------------------------------
--| Pascal Obry                           Team-Ada Member
--| 45, rue Gabriel Peri - 78114 Magny Les Hameaux FRANCE
--|------------------------------------------------------
--|    http://www.obry.net  -  http://v2p.fr.eu.org
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--|
--| gpg --keyserver keys.gnupg.net --recv-key F949BD3B

Re: Question: dynamic rename?

[Darkwing]

On Sep 3, 6:22 am, Pascal Obry <pas...@obry.net> wrote:
> Le 03/09/2011 14:27, ytomino a écrit :
>
>
> Or using a case expression in Ada 2012:
>
>     Signal : Signal_Type :=
>                (case Configuration is
>                    when One => Signal_One,
>                    when Two => Signal_Two);

You can really do that in Ada 2012? (I've never used 2012, just 95).

That's pretty cool. Any word on when 2012 will be finalized?

> function signal_ref return access signal_type is
> begin
>     case configuration is
>        when one =>  return signal_one'Access;
>        when two =>  return signal_two'Access;
>     end case;
> end signal_ref;

This is what I'll have to use. Well, actually just the value since I'm
only reading and not writing. Also, I don't think I have have access
to the 'access because the variables in question aren't aliased (I
don't believe they are aliasable either).

Re: Question: dynamic rename?

[Pascal Obry]

Le 04/09/2011 05:11, Darkwing a �crit :
> On Sep 3, 6:22 am, Pascal Obry<pas...@obry.net>  wrote:
>> Or using a case expression in Ada 2012:
>>
>>      Signal : Signal_Type :=
>>                 (case Configuration is
>>                     when One =>  Signal_One,
>>                     when Two =>  Signal_Two);
>
> You can really do that in Ada 2012? (I've never used 2012, just 95).

Yes, and this already works in GNAT recent versions. Not tested with 
GNAT GPL 2011 though.

> That's pretty cool. Any word on when 2012 will be finalized?

ISO standardization should be completed in 2012. Implementation of some 
features has already started in GNAT but for a full Ada 2012 support it 
will take some time. More information about Ada 2012:

    http://www.adacore.com/home/ada_answers/ada-2012/

    http://www.ada-auth.org/standards/ada12.html

You probably want to read this introduction to Ada 2012:

 
http://www2.adacore.com/wp-content/uploads/2006/03/Ada2012_Rational_Introducion.pdf

Pascal.

-- 

--|------------------------------------------------------
--| Pascal Obry                           Team-Ada Member
--| 45, rue Gabriel Peri - 78114 Magny Les Hameaux FRANCE
--|------------------------------------------------------
--|    http://www.obry.net  -  http://v2p.fr.eu.org
--| "The best way to travel is by means of imagination"
--|
--| gpg --keyserver keys.gnupg.net --recv-key F949BD3B

Re: Question: dynamic rename?

[Anh Vo]

On Sep 4, 1:43 am, Pascal Obry <pas...@obry.net> wrote:
> Le 04/09/2011 05:11, Darkwing a écrit :
>
> > On Sep 3, 6:22 am, Pascal Obry<pas...@obry.net>  wrote:
> >> Or using a case expression in Ada 2012:
>
> >>      Signal : Signal_Type :=
> >>                 (case Configuration is
> >>                     when One =>  Signal_One,
> >>                     when Two =>  Signal_Two);
>
> > You can really do that in Ada 2012? (I've never used 2012, just 95).
>
> Yes, and this already works in GNAT recent versions. Not tested with
> GNAT GPL 2011 though.

It does work with GNAT GPL 2011 On Windows at least.

Anh Vo