Re: Controlling endian-ness? (Example: Attribute Overriding)

[anon@anon.org (anon)]

--  File: newprog.adb
--
-- An example of how to Override an built-in Attribute:
-- Based on examples from RM 13.3 ( 84 ) and 13.13.2 ( 40 ) ;
--
with Interfaces ;
use  Interfaces ;

with Ada.Text_IO ;
use  Ada.Text_IO ;

with Ada.Streams.Stream_IO;

procedure NewProg is

  -----------------------------------------------------------

   type Unsigned_32 is new Interfaces.Unsigned_32 ; 

  --
  -- Define New Attribute Specifications
  --
   procedure newWrite
     ( Stream : access Ada.Streams.Root_Stream_Type'Class;
       Item   : in Unsigned_32 ) ;
                                           -- Performs Overriding of attribute
    for Unsigned_32'Write use newWrite ; 

  -----------------------------------------------------------

  --
  -- Define New Attribute Body
  --
   procedure newWrite
     ( Stream : access Ada.Streams.Root_Stream_Type'Class;
       Item   : in Unsigned_32 ) is
     begin
       --
       -- Replace with your "Write code"
       --
       -- test message only, just to prove that we are using this Attribute 
       --
       Put_Line ( "New Write Attribute" ) ; 
     end newWrite ;

  -----------------------------------------------------------

   Data_File      : Ada.Streams.Stream_IO.File_Type;
   Data_Stream    : Ada.Streams.Stream_IO.Stream_Access;
   The_Filename   : constant String :=  "Test.Dat" ;

  Test_Data : Unsigned_32 := 9 ;

begin

  Ada.Streams.Stream_IO.Create ( Data_File, 
                                 Ada.Streams.Stream_IO.Out_File,
                                 The_Filename ) ;

  Data_Stream := Ada.Streams.Stream_IO.Stream ( Data_File ) ;


  Put_Line ( "Testing: New Atrribute: Write" ) ;
  New_Line ;

  Unsigned_32'Write ( Data_Stream, Test_Data ) ;

  Ada.Streams.Stream_IO.Close ( Data_File ) ;

end NewProg ;

In <4898d0ca$0$19680$4d3efbfe@news.sover.net>, "Peter C. Chapin" <pcc482719@gmail.com> writes:
>anon wrote:
>
>> For using Unsigned_32. Why not just override the built-in Write attributes 
>> routines for Unsigned_32 by re-writing the attributes routines. This may at 
>> most require a new package with a few extra attributes routines that may 
>> be needed. Also, this will also allow you to use "Shift_Left/Shift_Right" 
>> directly with Unsigned_32.  
>> 
>> So in your program you could use:
>> 
>>    Data : Unsigned_32 ;
>>   ...
>>    Unsigned_32'Write ( Stream_Pointer, Data ) ;
>
>I actually tried something like this but the compiler told me that I 
>couldn't redefine attributes for that type (or something like that). I 
>think the problem is that since the type is defined in another package 
>it is already frozen or some such. It could also be that I did it wrong.
>
>Peter