Re: Protected types made of ADT's, and Passive Iterators

[Mats Weber <Mats.Weber@elca-matrix.ch>]

John Woodruff wrote:

> I can make a generic package that encapsulates a protected instance of
> List in a fairly straightforward way:

> BUT the base list ADT provided a passive iterator, and I'd like to offer
> that capability to the clients of my protected ADT as well.

This comes from Ada 95's failure to recognize generics as operations of a
type. You cannot declare generic task entries or generic protected operations.

The only way around the problem is to have a semaphore protecting the data in
your list, but there is no easy way of encapsulating your data into a task
safe construct (task or protected type).

I have discussed this issue in detail in my thesis
<http://lglwww.epfl.ch/Team/MW/Ada-Extensions/Ada-Extensions.html>.

I have some code doing what you want (implement an ADT and its protected form
with the same specification) for AVL trees. Mail me if you are interested.