Re: Unchecked deallocation question

[Jeffrey Carter <spam@spam.com>]

Alex R. Mosteo wrote:

> type Root is tagged record ...
> 
> type Root_Access is access Root;
> 
> type Derived is new Root with ...
> 
> type Derived_Access is access Derived;
> 
> procedure Free is
>    new Ada.Unchecked_Deallocation (Root'Class, Root_Access);

Root_Access designates Root, not Root'Class.

> 
> declare
>    It : Derived_Access := new Derived;
> begin
>    Free (Root_Access (It)); -- <-- THIS DEALLOCATION I'M ASKING
> end;
> 
> The purpose is to have a single deallocator in the root package and to 
> not have to instantiate a lot of deallocators for derived types.

You'd be better off having

type Root_Access is access Root'Class;

procedure Free is new ...

...

It : Root_Access := new Derived;

...

Free (It);

But you'd really be better off not using access types, or encapsulating 
and hiding their use if that's not possible.

-- 
Jeff Carter
"My name is Jim, but most people call me ... Jim."
Blazing Saddles
39