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Date: Fri, 26 Jun 2009 21:27:04 +0200
From: Damien Carbonne <damien.carbonne@free.fr>
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Subject: Re: Issue with GNAT GPL 2009 and GtkAda
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Date: 2009-06-26T21:27:05+02:00
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Dmitry A. Kazakov a �crit :
>> If this is true, it means that using in/out/in out modes is almost 
>> impossible in the code I write if this code must be mixed with code from 
>> third party libraries (like GtkAda) that use access almost everywhere. sad.
> 
> No, GtkAda does not use controlled or tagged types when it talks to Gtk.
> Such types should not have C convention. Instead of that GtkAda associates
> a C type with each tagged Ada one, which serves as a proxy. The address of
> this C object can be obtained using the Get_Object call. You will often
> find it in the implementation of GtkAda subroutines.
> 

Of course, but I did not meant use of access types to interface C API.
Just some examples from Gtk.Tree_Model:

    function Get_Iter_First
      (Tree_Model : access Gtk_Tree_Model_Record) return Gtk_Tree_Iter;

    function Get_Path
      (Tree_Model : access Gtk_Tree_Model_Record;
       Iter       : Gtk_Tree_Iter) return Gtk_Tree_Path;

    procedure Next
      (Tree_Model : access Gtk_Tree_Model_Record;
       Iter       : in out Gtk_Tree_Iter);

Why use access everywhere ? In the case of functions, one could argue 
that "in out" is not possible. But aren't there any cases where in is 
sufficient for functions ? And for procedures ? Why not write what this:
    procedure Next
      (Tree_Model : in [out] Gtk_Tree_Model_Record;
       Iter       : in out Gtk_Tree_Iter);

One obvious issue is that modes must be guessed from comments in 
original C code, or from the C code itself. Thys may be hard to find 
automatically.


Damien