Re: GCC 4.0 Ada.Containers Cursor danger.

["MMM" <terekhov@emc.com>]

Randy Brukardt wrote:
>
> Because a hash implementation is impossible for Ada unless you make it
> visible to the user (by passing a hash function as a generic parameter). At
> which point it is no longer unordered, it has turned into an "unspecified
That is not correct in general. That is correct if you explicitly
require order preserving hash function. See for example
http://www.nist.gov/dads/HTML/orderpresmph.html
In general order is implementation dependent and in some cases depends
on insertion order.
> ordered" container. As a practical matter, a hashed container is much harder
> for the user to use than an ordered one. (An ordered one always will work
Use an ordered one then - list or vector.
> with reasonable time complexity; a hashed one is very sensitive to the
That depends on the task at hand of course.
> quality of the hash function. Writing a good hash function is an art, not a
> science, and often the best answer is not obvious. I always run tests for
> various hash functions on sample data, and that is not practical for the Q&D
> uses that containers are best suited for.)
> 
>                    Randy.
> 
Mikhail