Re: Not null feature with anonymous and named access types

["Alex R. Mosteo" <devnull@mailinator.com>]

Anh Vo wrote:

> 
> Dmitry A. Kazakov wrote:
>> On 12 Jun 2006 16:13:34 -0700, Anh Vo wrote:
>>
>> > Bj�rn Persson wrote:
>> >> Anh Vo wrote:
>> >>> I have been exploring the not null feature with anonymous access type
>> >>> and named access type. One thing have learned that an access variable
>> >>> declared based on these types will raise a Constraint_Error when
>> >>> deallocating this access variable as shown in the code below.
>> >>
>> >> Of course. Deallocation sets the access variable to null, and that
>> >> violates the not-null constraint.
>> >>
>> > Thanks for your quick reply.
>> >
>> > Based on this requirement, one should not use not null access in this
>> > case due to memory leak as the result of memory deallocation
>> > incapability.
>>
>> Often memory management and handling objects should be well separated. In
>> public interfaces, where pointers are needed, null access types can be
>> very useful. This by no means should prevent the implementation
>> interfaces from using plain pointers, arena allocators, garbage
>> collectors, etc to manage memory.
> 
> Agreed. However, memory leak occurs when the scope is complete in this
> case. Therefore, not null access should be used with extreme care.
> Otherwise, memory leak is almost certain.

I don't see anything has radically changed in this respect since Ada95. You
expose in the spec a not null type and in body use some nullable type for
unchecked deallocations, if necessary.