Re: Issue with GNAT GPL 2009 and GtkAda

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Thu, 25 Jun 2009 15:49:58 -0500, Randy Brukardt wrote:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
> news:1avd65rn49abv$.krcxo2gdzb16$.dlg@40tude.net...
> ...
>> Yes, but that is not necessarily a compiler bug. It is quite simple to
>> create a serious problem to oneself:
>>
>> declare
>>   Ptr : access T := new T;
>> begin
> 
> Allocators of anonymous access types are almost never what you want. This is 
> so true, in fact, that we have proposed a Restriction for this 
> "No_Anonymous_Allocators", which I recommend is part of every program. (Of 
> course, that will have to wait until compilers implement it; it wasn't 
> formally proposed until 3 weeks ago, but it was accepted at the Brest 
> meeting and thus will appear in the next working draft).

The only purpose of

   Ptr : access T := new T;

I can guess is allocation of a large scoped object on the heap. It would be
better if there were a syntax for that, which does not involve access
types.

   Object : new T;

or

   Object : T'Pool;

or

   Object : T;
   for Object'Storage_Pool use System.Default_Storage_Pool;

etc.

Access types are much overused in Ada in order to overcome language
problems unrelated to access types.

Just to remember: access discriminants (MI for poor), the Rosen trick (in
out parameters of a function), return by access (a patch where in-place
results should have been) and so on.

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