Re: Generic Embedded List Nodes

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

On 21/06/2016 07:52, Niklas Holsti wrote:

> If you don't get the address arithmetic to work,

There is a subtle difference between access and X'Address, but otherwise 
address arithmetic works. E.g. I can instantiate my implementation of 
linked lists with any type including unconstrained and non-tagged ones.

> I believe that a set of
> mixin-generics could be used to add as many embedded Emb_Nodes to a
> tagged limited record, with access discriminants pointing to the
> containing record.

Adding links afterwards is even worse than deriving objects from a 
abstract list node. Any derivation must be used sparingly in Ada which 
does not have full multiple inheritance. Once you have spent the proper 
parent type you won't get another one.

> This would eliminate the address arithmetic, at the
> cost of increasing the size of the record by the sizes of the
> discriminants (not a great deal).

The advantage of pool-based design is that no address arithmetic is 
needed for object operations. The list element is access to the object 
type. Address arithmetic is needed for list operations only.

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