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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Your wish list for Ada 202X
Date: Wed, 23 Apr 2014 16:38:56 +0200
Organization: cbb software GmbH
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Date: 2014-04-23T16:38:56+02:00
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On Wed, 23 Apr 2014 15:57:03 +0200, J-P. Rosen wrote:

> Le 23/04/2014 14:55, björn lundin a écrit :
> 
>> I'd like V'Img to be standard ada like T'Image(V); As in the gnat
>> implementation
>> 
> No big cost, no big benefit...
> 
>> Also, I'd like to be able to define the string function for a record
>> type to be used for the 'image attribute.
>> 
>> type T2 is record A : T; B : T; end record;
>> 
>> function F_T2_Image(O : T2) return String is begin return O.A'Img & "
>> " O.B'Img; end F_T2_Image;
>> 
>> for T2'Image use F_T2_Image
>> 
>> V2 : T2; .. Put_Line(V2'Img);
>> 
> And what is the benefit over writing:
>    Put_Line (F_T2_Image (V2));
> ?

generic
    type T is private;
package Foo is ...

package body Foo is
   procedure Bar (X : T) is
   begin
       ... X'Img ...
 
That is the only use case for an attribute, in absence of primitive
operations of course.

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