Re: Exceptions and Streams

[Simon Wright <simon@pushface.org>]

"REH" <spamjunk@stny.rr.com> writes:

> 1) Does 11.4.1 (16) of the RM (see below) say that I can stream an
> exception occurrance to another address space and re-raise it?  Note
> that I am not using "partitions" as defined in the Distributed Ada
> Annex, but just separate address spaces.

I have certainly had trouble streaming ::something to do with
exceptions:: with GNAT, but I'm afraid I can't remember what. The
symptom was an endless recursion, I think. Not much help, I know.

One thought: with 'gnatbind -E', GNAT keeps a traceback in the
occurence, but it's in terms of addresses so may not make a lot of
sense in another address space. This can also cause confusion in
exceptions raised during rendezvous if the traceback is reported from
the caller's point of view!

> 2) Is there an easy way to determine the number of elements an
> object of a given type will write to a stream before hand?  I need
> to know how big to make the array to hold all a procedures
> parameters, and I don't want to have to hard-code things like dupe
> vector sizes.

You might find it easier to create a stream which could extend itself
on overflow?

I found 'Max_Size_In_Storage_Elements + 128 worked well (the streamed
version will very likely be smaller than 'Max_Size.., plus something
for the constraints).