Dot notation in Ada 2005

Dot notation in Ada 2005

[Philippe Tarroux]

I am testing some features of the new Ada 2005 version. Here a simple 
problem that seems to me rather a gnat bug than a limitation of the 
norm. With the code:

------
package Objs is

  type Point is tagged null record;

end Objs;

------
package Objs.ext_objs is

  type New_Point is new Point With private;
  function X (P : New_Point) return Integer;

private
  type New_Point is new Point with record
     X1, Y1 : Integer := 0;
  end record;
end Objs.ext_objs;

------
package body Objs.Ext_Objs is

  function X (P : New_Point) return Integer is
  begin
     return P.X1;
  end X;

  procedure Test ( A : Integer; Y : Integer) is
  begin
     null;
  end Test;

  procedure Draw (A : Integer; P : New_Point) is
  begin
     Test (A, P.X);  -- PROBLEM HERE
  end Draw;

end Objs.Ext_Objs;

i get a compilation error ("no selector X for private type P") when P.X 
is not the first argument of the function Test.

It seems to me a rather strange behavior.

Some explanation?

Philippe Tarroux

Re: Dot notation in Ada 2005

[Martin Carlisle]

Your forgot the -gnat05 flag.  See below:

C:\d\temp>gnatmake -g objs-ext_objs
gcc -c -g objs-ext_objs.adb
objs-ext_objs.adb:21:16: no selector "X" for type "New_Point" defined
at objs-ex
t_objs.ads:12
gnatmake: "objs-ext_objs.adb" compilation error

C:\d\temp>gnatmake -g -gnat05 objs-ext_objs
gcc -c -g -gnat05 objs-ext_objs.adb
gcc -c -g -gnat05 objs.ads

c:\d\temp>

--Martin Carlisle

Re: Dot notation in Ada 2005

[Philippe Tarroux]

Martin Carlisle a �crit :

>Your forgot the -gnat05 flag.  See below:
>
>C:\d\temp>gnatmake -g objs-ext_objs
>gcc -c -g objs-ext_objs.adb
>objs-ext_objs.adb:21:16: no selector "X" for type "New_Point" defined
>at objs-ex
>t_objs.ads:12
>gnatmake: "objs-ext_objs.adb" compilation error
>
>C:\d\temp>gnatmake -g -gnat05 objs-ext_objs
>gcc -c -g -gnat05 objs-ext_objs.adb
>gcc -c -g -gnat05 objs.ads
>
>c:\d\temp>
>
>--Martin Carlisle
>  
>
Unfortunately not:

gnatmake -u -c -u -PD:/users/philippe/src/ada/tests/objs/objs_test.gpr 
objs-ext_objs.adb -d
gcc -c -gnat05 -I- -gnatA 
D:\users\philippe\src\ada\tests\objs\objs-ext_objs.adb
objs-ext_objs.adb:16:16: no selector "X" for type "New_Point" defined at 
objs-ext_objs.ads:9
gnatmake: "d:\users\philippe\src\ada\tests\objs\objs-ext_objs.adb" 
compilation error

What compiler do you use?

Philippe Tarroux

Re: Dot notation in Ada 2005

[Marc Enzmann]

Hm, somewhat familiar. Something like

   type My_Private_Class is private;
   ...
   procedure Do_Something (Argument : in out My_Private_Class);
   ...
private
   type My_Private_Class is tagged record
      ...
   end record;
   ...

can be called by
   ...
   An_Argument : My_Private_Class;
   ...
   Do_Something (An_Argument);
   ...

but not by
   ...
   An_Argument.Do_Something;

However, if My_Private_Class is not declared as private, then anything
goes....

What am I missing ???
(BTW: using gcc version 3.4.5 20050524 (prerelease) for GNAT GPL 2005
under Mac OS 10.4)

Re: Dot notation in Ada 2005

[christoph.grein]

My_Private_Class is not visibly tagged. AFAICS, dot notation is allowed
only for objects of types that are visibly tagged at that place (Ada
2005 only of course).

Re: Dot notation in Ada 2005

[Marc Enzmann]

Upps !  Just replace:
   ...
   type My_Private_Class is private;
   ...

with
   ...
   type My_Private_Class is tagged private;
   ...

ooohhhkay !  Thanks for the lighting-fast response !

Re: Dot notation in Ada 2005

[Martin Carlisle]

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