Re: smart pointer dangerous (no -> operator)

[Brian Drummond <brian_drummond@btconnect.com>]

On Fri, 16 Jan 2009 12:09:16 +0100, "Dmitry A. Kazakov"
<mailbox@dmitry-kazakov.de> wrote:

>1. In Ada 95 I declare the proxy type tagged controlled. The handle is
>created through a instantiation in the private part of the generic package
>Handle:
>
>   type X_Handle is new Ada.Finalization.Controlled with private;
>      -- Repeat all operations of the target
>   procedure Foo (Object : X_Handle);
>   ... -- and so on
>private
>   package Handles is not Object.Handle (...); -- Instantiation
>   type X_Handle is new Handles.Handle with null record;
>
>The implementation of Foo goes as follows:
>
>   procedure Foo (Object : X_Handle) is
>   begin
>       Foo (Ptr (Object).all);
>   end Foo;
>
>this is extremely tedious, but the best way I know.

As an Ada newbie, I've probably lost track of something important, but
I can't see a reason not to create a generic procedure, and simply
instantiate it for each Foo, which would be slightly less boring if it
worked..

I suspect it can't be that simple, but I can't see why. You don't know
the type of Ptr (Object).all but can't it be private from the generic's
point of view, or is that where a generic falls apart? Whatever the
type, there must be a Foo() for it, or the above wouldn't compile.

-Brian