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From: "Anh Vo" <anhvofrcaus@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Not null feature with anonymous and named access types
Date: 14 Jun 2006 20:48:28 -0700
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Dmitry A. Kazakov wrote:
> On 14 Jun 2006 08:37:13 -0700, Anh Vo wrote:
>
> via *this* pointer, which does not mean that it cannot be reclaimed at all.
> Consider trivial stack allocated aliased variable.

I am afraid I do not understand "this* pointer means. What I was
talking about not null access object using heap memory, not aliased
variable at all. See my code snipet from my original post.

> No, you just don't use not-null pointers where deallocation is possible /
> necessary. That's the very idea of not-null pointers.

I weight memory leak more important than convenient way of using null
excluded pointer. I am fine with not null pointer pointing to an
aliased object. In this case, attemptingp to deallocate the pointer is
clearly a language violation.

> For example, consider an implementation of a container. Its public
> operation Get_Element could return a not-null pointer to the element,
> ensuring two things: 1. the client will never get a null (so no need to
> check it) 2. the client will never be able to deallocate the element
> through the pointer returned. Internally the implementation may allocate
> and deallocate elements using other pointers. So another operation
> Remove_Element_By_Index would do it.
>
> [It is still unsafe, as any aliasing is, yet definitely better than
> nullable pointers.]

There is no disagreement here.

AV