Re: limited agregate and limited components default initialization

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

On 2018-04-02 20:19, Jere wrote:

> Something else unrelated to your question, but that I just noticed: Assuming
> you could have gotten a list definition that you were happy with, there is
> still a very serious problem with it.  Doubly linked lists (ones that use
> both Next and Prev/Pred) are susceptible to "circular references" when using
> reference counting smart pointers.  You would need to use a weak reference
> based smart pointer for one of the two (either Next or Prev/Pred, whichever
> you prefer).
> 
> -- very simple/silly example
> type Node is
>     Value : Item_Type;
>     Next  : Smart_Pointer_Type;
>     Prev  : Weak_Smart_Pointer_Type;
> end Node;

This is still circular. Weak/strong references work only in hierarchical 
structures. If a doubly-linked list must deploy them then it should be 
the head holding references to all nodes. It does not make much sense 
though.

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