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Newsgroups: comp.lang.ada
Date: Mon, 14 Sep 2020 03:47:06 -0700 (PDT)
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Subject: Re: Visibility issue
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> hierarchy be a child hierarchy of your interface hierarchy. It's undoubte=
dly=20
> possible to design such a system so your implementation hierarchy does no=
t need=20
> to be a child hierarchy, but where things are declared and what is visibl=
e where=20
> would be different.
Thank you for your answer. =C2=BF Do you know some idea or design pattern t=
o achieve this?
I didn't write it in the example for simplicity, but the user have to set a=
 callback function.
This callback function is triggered in the internal implementation hierarch=
y packages. Let me show you. the questions are inside comments:

--- API SIDE: -----
package API.Callbacks
   type Handle is tagged private
   type pointer_to_Procedure is access procedure (Self : API.CAllbacks.Hand=
le );
   procedure Set_Callback (Self: in out API_HandleCallBack; cp: CallbackPro=
cedure  );

private  =20
   type Handle is tagged record
      Hidden : Natural;
   end record;
  procedure Hidden_constructor (S: in out Handle'Class ; Hidden_content :Na=
tural);
---------------
----- IMPLEMENTING SIDE: --------
with API.Callbacks;
package body Internal.TASKS_Callbacks is

task body Caller is

 MyHandle : API.Handle;
 cp: CallbackProcedure :=3D Get_from_pool_of_callbacks;
begin
   --Cannot access to private part for API.Handle from here :(
   -- Just want to set a hidden content from here using Hidden_Constructor =
and later call:
   cp (MyHandle);
end Caller;