Re: Pragma for conditional compilation? (Ada 2005 vs. 95)

[anon@anon.org (anon)]

As for the "pragma Ada_05 ( name ) ;" It looks like it will not 
work for your "Ada_95" user defined package and "Ada_05" Ada 
defined package.
 
Now for conditional compilation, well I did forget to add the 
sixth one. Which is the laymans answer and it always works, if you 
follow the instructions. 
--
-- Uncomment one and only one of the following lines:
--
-- with Package_1 ; use Package_1 ;  -- Ada_95 version package

-- with Package_2 ; use Package_2 ;  -- Ada_2005 version package



Now to show one example of the IF-THEN-ELSE-END concept. And it 
is a lot of work if you have more than a couple of routines to 
set up. 

-- -------- --
-- TEST.ADB --
-- -------- --
--
-- There are a number of ways to use the "IF-THEN-ELSE-END" 
-- structure, this version is one. And it does generate code 
-- for the "IF-THEN-ELSE-END" statements.  
--

with Test1 ;

procedure test is

  --
  -- True:  use Alpha routines aka "user included package"
  --
  -- False: use Beta routine aka "system define package"
  --
  package IO_Package is new Test1 ( False ) ;

  use IO_Package ; -- Assign default package

  --
  -- Use User created package 
  --
  package Package_IO is new Test1 ( True ) ;


begin

  Put_Line.all ( "This is a test" ) ;

  Package_IO.Put_Line.all ( "Try this One" ) ;

end test ;


-- --------- --
-- TEST1.ADS --
-- --------- --

--
-- This Generic package defines the program global routines, the 
-- redefined Ada system routines and the user created routines.
--
with Ada.Text_IO ;

generic

  Configure : boolean ; 

package test1 is

  type Procedure_String_Type is access procedure ( item : String ) ;

  -------------------------------
  -- Define package procedures --
  -------------------------------
   Put_Line : Procedure_String_Type ; 

   --
   -- define other declared routines/variables needed
   --

private

  -------------------------------
  -- Emulate system procedures --
  -------------------------------
  procedure Alpha ( szTemp : string ) ;


  -----------------------------------------------
  -- Redefine/Rename system supplied procedure --
  -----------------------------------------------

  procedure Beta ( Item : in String ) renames Ada.Text_IO.Put_Line ;

end test1 ;


-- --------- --
-- TEST1.ADB --
-- --------- --

--
-- This Generic body package defines the user created routines and 
-- this package does contain a initialize routine that configures 
-- the package.
--

--
-- IF-THEN-ELSE-END -- Yes, the compiler does generate code for 
--                  -- this type of statament.
--                  -- Also, it is easy to insert a statement in
--                  -- the wrong place.
--
-- This works! Even though there is a person that says this will 
-- not work.
-- If this does not you better find a different language to use.
-- Because it means the Ada "IF" statement does not work?
--

with Ada.Text_IO ;

package body test1 is

  -------------------------------
  -- Emulate system procedures --
  -------------------------------
  procedure Alpha ( szTemp : string ) is
    begin
      Ada.Text_IO.Put_Line ( "Alpha: " & szTemp ) ;
    end ;

-----------------------
--  Initial package  --
-----------------------
  begin -- test1
     --
     -- Like I said, this is the old way of doing this by embedding 
     -- the configuration code in the source. But it does work. 
     -- Of course you could use a CASE statement instead, if you need 
     -- more than two options or packages set up.
     --
    if Configure then 
      Put_Line := Alpha'Access ;
    else
      Put_Line := Beta'Access ;
    end if ;

  end test1 ;




In <1190929570.915553.284000@19g2000hsx.googlegroups.com>,  Jerry <lanceboyle@qwest.net> writes:
>On Sep 27, 8:26 am, a...@anon.org (anon) wrote:
>
>Thanks, anon, for the detailed answer.
>
>>
>> The third real old way is to code in the option by a "IF-THEN-ELSE-END"
>> statements and use a Global constant variable(s). Its low tech but it
>> still works.
>
>OK, but my "problem" is in declaring types which I want to be visible
>in 95 but not visible in 05, as 05 provides them itself. An "IF-THEN-
>ELSE-END" solution would have to be in the executable part of the
>program (right?).
>
>
>> The fifth is a "NON STANDARD" way that GNAT introduce with the
>> pre-release of Ada_2005 which is to use the "pragma Ada_05 ( name ) ;"
>>
>> Example:
>>
>> -- For GNAT you can create a routine that is define and is usable
>> -- only in Ada_2005 specs, by using the GNAT pragma Ada_05.
>> --
>> -- Gnat uses this concept in the  Ada.Text_IO package. Just
>> -- search for "Ada_05" in the file "a-textio.ads". There are
>> -- two Get_Line functions. If the system is compiled with
>> -- "pragma Ada_83 ;" or "pragma Ada_95" the compile will not
>> -- allow a call to these routines. But under Ada_05 the routine is
>> -- visible.
>> --
>> -- Defined in the specification file.
>>
>>    procedure Routine ;
>>    pragma Ada_05 ( Routine ) ;
>>
>> --
>> -- Defined in the body file.
>> --
>>    procedure Routine is
>>      begin -- Routine
>>         null ;
>>      end Routine ;
>>
>Same comment as above--how would this work for type declarations?
>Could I follow the type declaration with the pragma? Also, I need to
>conditionally have a with clause. For example, if using Ada 2005, I
>need a line like this:
>
>  with Ada.Numerics.Long_Real_Arrays;
>  use  Ada.Numerics.Long_Real_Arrays;
>
>(This is where the vector and matrix declarations are.)
>
>Jerry
>
>